Live vaccinations in dermatology for immunosuppressed patients: a narrative review

Given the higher susceptibility to infectious disease in patients receiving immunosuppressive therapies for inflammatory dermatologic conditions, immunization is important in this population. While live vaccines protect against life-threatening diseases, they can be harmful in immunosuppressed patients given the risk of replication of the attenuated pathogen and adverse reactions. The utilization of live vaccines in immunosuppressed patients depends on multiple factors such as the vaccine and therapy regimen. To provide an overview of evidence-based recommendations for the use of live vaccines in patients receiving immunosuppressive therapies for dermatological conditions. A literature search of the PubMed database was performed using keywords live vaccine, live-attenuated vaccine, dermatology, immunosuppressed, and immunocompromised, and specific immunosuppressive therapies: corticosteroids, glucocorticoids, methotrexate, azathioprine, cyclosporine, mycophenolate mofetil, biologics. Relevant articles written in English were included. Using these keywords, 125 articles were reviewed, of which 28 were ultimately selected. Recommendations for live vaccines can be determined on a case-by-case basis. Measles, mumps, rubella, varicella (MMRV) vaccines may be safely administered to patients on low-dose immunosuppressive agents while the yellow fever vaccine is typically contraindicated. It may be safe to administer live MMRV boosters to children on immunosuppressive therapies and the live herpes zoster vaccine to patients on biologics. Given poor adherence to immunization guidelines in immunosuppressed patients, dermatologists have a critical role in educating patients and general practitioners regarding live vaccines. By reviewing a patient's vaccination history and following immunization guidelines prior to initiating immunosuppressive therapies, physicians can mitigate morbidity and mortality from vaccine-preventable diseases.

FAdV-4 without Fiber-2 Is a Highly Attenuated and Protective Vaccine Candidate

Hepatitis-hydropericardium syndrome (HHS) caused by the highly pathogenic fowl adenovirus serotype 4 (FAdV-4) has resulted in huge economic losses to the poultry industry globally. The fiber-2 gene, as a major virulence determiner, is also an important vaccine target against FAdV-4. In this study, we used a CRISPR/Cas9-based homology-dependent recombinant technique to replace the fiber-2 gene with egfp and generate a novel recombinant virus, designated FAdV4-EGFP-rF2. Although FAdV4-EGFP-rF2 showed low replication ability compared to the wild-type FAdV-4 in LMH cells, FAdV4-EGFP-rF2 could effectively replicate in LMH-F2 cells with the expression of Fiber-2. Moreover, FAdV4-EGFP-rF2 was not only highly attenuated in chickens, but also could provide efficient protection against a lethal challenge of FAdV-4. Moreover, FAdV4-EGFP-rF2 without fiber-2 could induce neutralizing antibodies at the same level as FA4-EGFP with fiber-2. These results clearly demonstrate that although fiber-2 affects the viral replication and pathogenesis of FAdV-4, it is not necessary for virus replication and induction of neutralizing antibodies; these findings provide novel insights into the roles of fiber-2 and highlight fiber-2 as an insertion site for generating live-attenuated FAdV-4 vaccines against FAdV-4 and other pathogens. IMPORTANCE Among all serotypes of fowl adenovirus, serotypes FAdV-1, FAdV-4, and FAdV-10 are unique members with two fiber genes (fiber-1 and fiber-2). Recent studies reveal that Fiber-1, not Fiber-2, directly triggers viral infection of FAdV-4, whereas Fiber-2, but not Fiber-1, has been identified as the major virulence determiner and an efficient protective immunogen for subunit vaccines. Here, we replaced fiber-2 with egfp to generate a novel recombinant virus, designated FAdV4-EGFP-rF2. In vitro and in vivo studies on FAdV4-EGFP-rF2 revealed that fiber-2 was not necessary for either virus replication or efficient protection for FAdV-4; these results not only provide a novel live-attenuated vaccine candidate against HHS, but also give new ideas for generating a FAdV-4 based vaccine vector against other pathogens.

Impact of maternal antibodies and microbiota development on the immunogenicity of oral rotavirus vaccine in African, Indian, and European infants

Identifying risk factors for impaired oral rotavirus vaccine (ORV) efficacy in low-income countries may lead to improvements in vaccine design and delivery. In this prospective cohort study, we measure maternal rotavirus antibodies, environmental enteric dysfunction (EED), and bacterial gut microbiota development among infants receiving two doses of Rotarix in India (n = 307), Malawi (n = 119), and the UK (n = 60), using standardised methods across cohorts. We observe ORV shedding and seroconversion rates to be significantly lower in Malawi and India than the UK. Maternal rotavirus-specific antibodies in serum and breastmilk are negatively correlated with ORV response in India and Malawi, mediated partly by a reduction in ORV shedding. In the UK, ORV shedding is not inhibited despite comparable maternal antibody levels to the other cohorts. In both India and Malawi, increased microbiota diversity is negatively correlated with ORV immunogenicity, suggesting that high early-life microbial exposure may contribute to impaired vaccine efficacy.

A single intranasal dose of a live-attenuated parainfluenza virus-vectored SARS-CoV-2 vaccine is protective in hamsters

Single-dose vaccines with the ability to restrict SARS-CoV-2 replication in the respiratory tract are needed for all age groups, aiding efforts toward control of COVID-19. We developed a live intranasal vector vaccine for infants and children against COVID-19 based on replication-competent chimeric bovine/human parainfluenza virus type 3 (B/HPIV3) that express the native (S) or prefusion-stabilized (S-2P) SARS-CoV-2 S spike protein, the major protective and neutralization antigen of SARS-CoV-2. B/HPIV3/S and B/HPIV3/S-2P replicated as efficiently as B/HPIV3 in vitro and stably expressed SARS-CoV-2 S. Prefusion stabilization increased S expression by B/HPIV3 in vitro. In hamsters, a single intranasal dose of B/HPIV3/S-2P induced significantly higher titers compared to B/HPIV3/S of serum SARS-CoV-2-neutralizing antibodies (12-fold higher), serum IgA and IgG to SARS-CoV-2 S protein (5-fold and 13-fold), and IgG to the receptor binding domain (10-fold). Antibodies exhibited broad neutralizing activity against SARS-CoV-2 of lineages A, B.1.1.7, and B.1.351. Four weeks after immunization, hamsters were challenged intranasally with 104.5 50% tissue-culture infectious-dose (TCID50) of SARS-CoV-2. In B/HPIV3 empty vector-immunized hamsters, SARS-CoV-2 replicated to mean titers of 106.6 TCID50/g in lungs and 107 TCID50/g in nasal tissues and induced moderate weight loss. In B/HPIV3/S-immunized hamsters, SARS-CoV-2 challenge virus was reduced 20-fold in nasal tissues and undetectable in lungs. In B/HPIV3/S-2P-immunized hamsters, infectious challenge virus was undetectable in nasal tissues and lungs; B/HPIV3/S and B/HPIV3/S-2P completely protected against weight loss after SARS-CoV-2 challenge. B/HPIV3/S-2P is a promising vaccine candidate to protect infants and young children against HPIV3 and SARS-CoV-2.

Intramuscular Vaccination With the HSV-1(VC2) Live-Attenuated Vaccine Strain Confers Protection Against Viral Ocular Immunopathogenesis Associated With γδT Cell Intracorneal Infiltration

Herpes simplex virus type-1 (HSV-1) ocular infection is one of the leading causes of infectious blindness in developed countries. The resultant herpetic keratitis (HK) is caused by an exacerbated reaction of the adaptive immune response that persists beyond virus clearance causing substantial damage to the cornea. Intramuscular immunization of mice with the HSV-1(VC2) live-attenuated vaccine strain has been shown to protect mice against lethal ocular challenge. Herein, we show that following ocular challenge, VC2 vaccinated animals control ocular immunopathogenesis in the absence of neutralizing antibodies on ocular surfaces. Ocular protection is associated with enhanced intracorneal infiltration of γδ T cells compared to mock-vaccinated animals. The observed γδ T cellular infiltration was inversely proportional to the infiltration of neutrophils, the latter associated with exacerbated tissue damage. Inhibition of T cell migration into ocular tissues by the S1P receptors agonist FTY720 produced significant ocular disease in vaccinated mice and marked increase in neutrophil infiltration. These results indicate that ocular challenge of mice immunized with the VC2 vaccine induce a unique ocular mucosal response that leads into the infiltration of γδ T cells resulting in the amelioration of infection-associated immunopathogenesis.

COMMITTEE ON INFECTIOUS DISEASES. Recommendations for Prevention and Control of Influenza in Children, 2021-2022

This technical report accompanies the recommendations of the American Academy of Pediatrics for the routine use of the influenza vaccine and antiviral medications in the prevention and treatment of influenza in children during the 2021-2022 season. Influenza vaccination is an important intervention to protect vulnerable populations and reduce the burden of respiratory illnesses during circulation of severe acute respiratory syndrome coronavirus 2, which is expected to continue during this influenza season. In this technical report, we summarize recent influenza seasons, morbidity and mortality in children, vaccine effectiveness, vaccination coverage, and detailed guidance on storage, administration, and implementation. We also provide background on inactivated and live attenuated influenza vaccine recommendations, vaccination during pregnancy and breastfeeding, diagnostic testing, and antiviral medications for treatment and chemoprophylaxis.

Childhood Vaccinations and Type 1 Diabetes

Type 1 diabetes (T1D) is the most common paediatric endocrine disease, and its frequency has been found to increase worldwide. Similar to all conditions associated with poorly regulated glucose metabolism, T1D carries an increased risk of infection. Consequently, careful compliance by T1D children with schedules officially approved for child immunization is strongly recommended. However, because patients with T1D show persistent and profound limitations in immune function, vaccines may evoke a less efficient immune response, with corresponding lower protection. Moreover, T1D is an autoimmune condition that develops in genetically susceptible individuals and some data regarding T1D triggering factors appear to indicate that infections, mainly those due to viruses, play a major role. Accordingly, the use of viral live attenuated vaccines is being debated. In this narrative review, we discussed the most effective and safe use of vaccines in patients at risk of or with overt T1D. Literature analysis showed that several problems related to the use of vaccines in children with T1D have not been completely resolved. There are few studies regarding the immunogenicity and efficacy of vaccines in T1D children, and the need for different immunization schedules has not been precisely established. Fortunately, the previous presumed relationship between vaccine administration and T1D appears to have been debunked, though some doubts regarding rotavirus vaccines remain. Further studies are needed to completely resolve the problems related to vaccine administration in T1D patients. In the meantime, the use of vaccines remains extensively recommended in children with this disease.

Deletion Mutants of the Attenuated Recombinant ASF Virus, BA71ΔCD2, Show Decreased Vaccine Efficacy

African swine fever (ASF) has become the major threat to the global swine industry. Lack of available commercial vaccines complicates the implementation of global control strategies. So far, only live attenuated ASF viruses (ASFV) have demonstrated solid protection efficacy at the experimental level. The implementation of molecular techniques has allowed the generation of a collection of deletion mutants lacking ASFV-specific virulence factors, some of them with promising potential as vaccine candidates against the pandemic genotype II ASFV strain currently circulating in Africa, Europe, Asia and Oceania. Despite promising results, there is room for improvement, mainly from the biosafety point of view. Aiming to improve the safety of BA71∆CD2, a cross-protective recombinant live attenuated virus (LAV) lacking the ASFV CD2v gene (encoding β-glucuronidase as a reporter gene) available in our laboratory, three new recombinants were generated using BA71∆CD2 as a template: the single mutant BA71∆CD2f, this time containing the fluorescent mCherry reporter gene instead of CD2v, and two double recombinants lacking CD2v and either the lectin gene (EP153R) or the uridine kinase (UK) gene (DP96R). Comparative in vivo experiments using BA71∆CD2f, BA71∆CD2DP96R and BA71∆CD2EP153R recombinant viruses as immunogens, demonstrated that deletion of either DP96R or EP153R from BA71∆CD2f decreases vaccine efficacy and does not improve safety. Our results additionally confirm ASFV challenge as the only available method today to evaluate the protective efficacy of any experimental vaccine. We believe that understanding the fine equilibrium between attenuation and inducing protection in vivo deserves further study and might contribute to more rational vaccine designs in the future.

Rational Design of Live-Attenuated Vaccines against Herpes Simplex Viruses

Diseases caused by human herpes simplex virus types 1 and 2 (HSV-1 and HSV-2) affect millions of people worldwide and range from fatal encephalitis in neonates and herpes keratitis to orofacial and genital herpes, among other manifestations. The viruses can be shed efficiently by asymptomatic carriers, causing increased rates of infection. Viral transmission occurs through direct contact of mucosal surfaces followed by initial replication of the incoming virus in skin tissues. Subsequently, the viruses infect sensory neurons in the trigeminal and lumbosacral dorsal root ganglia, where they are primarily maintained in a transcriptionally repressed state termed "latency", which persists for the lifetime of the host. HSV DNA has also been detected in other sympathetic ganglia. Periodically, latent viruses can reactivate, causing ulcerative and often painful lesions primarily at the site of primary infection and proximal sites. In the United States, recurrent genital herpes alone accounts for more than a billion dollars in direct medical costs per year, while there are much higher costs associated with the socio-economic aspects of diseased patients, such as loss of productivity due to mental anguish. Currently, there are no effective FDA-approved vaccines for either prophylactic or therapeutic treatment of human herpes simplex infections, while several recent clinical trials have failed to achieve their endpoint goals. Historically, live-attenuated vaccines have successfully combated viral diseases, including polio, influenza, measles, and smallpox. Vaccines aimed to protect against the devastation of smallpox led to the most significant achievement in medical history: the eradication of human disease by vaccination. Recently, novel approaches toward developing safe and effective live-attenuated vaccines have demonstrated high efficacy in various preclinical models of herpetic disease. This next generation of live-attenuated vaccines has been tailored to minimize vaccine-associated side effects and promote effective and long-lasting immune responses. The ultimate goal is to prevent or reduce primary infections (prophylactic vaccines) or reduce the frequency and severity of disease associated with reactivation events (therapeutic vaccines). These vaccines' "rational" design is based on our current understanding of the immunopathogenesis of herpesviral infections that guide the development of vaccines that generate robust and protective immune responses. This review covers recent advances in the development of herpes simplex vaccines and the current state of ongoing clinical trials in pursuit of an effective vaccine against herpes simplex virus infections and associated diseases.

Immunogenicity of an oral rotavirus vaccine administered with prenatal nutritional support in Niger: A cluster randomized clinical trial

BACKGROUND

Nutritional status may play a role in infant immune development. To identify potential boosters of immunogenicity in low-income countries where oral vaccine efficacy is low, we tested the effect of prenatal nutritional supplementation on immune response to 3 doses of a live oral rotavirus vaccine.

METHODS AND FINDINGS

We nested a cluster randomized trial within a double-blind, placebo-controlled randomized efficacy trial to assess the effect of 3 prenatal nutritional supplements (lipid-based nutrient supplement [LNS], multiple micronutrient supplement [MMS], or iron-folic acid [IFA]) on infant immune response (n = 53 villages and 1,525 infants with valid serology results: 794 in the vaccine group and 731 in the placebo group). From September 2015 to February 2017, participating women received prenatal nutrient supplement during pregnancy. Eligible infants were then randomized to receive 3 doses of an oral rotavirus vaccine or placebo at 6-8 weeks of age (mean age: 6.3 weeks, 50% female). Infant sera (pre-Dose 1 and 28 days post-Dose 3) were analyzed for anti-rotavirus immunoglobulin A (IgA) using enzyme-linked immunosorbent assay (ELISA). The primary immunogenicity end point, seroconversion defined as ≥3-fold increase in IgA, was compared in vaccinated infants among the 3 supplement groups and between vaccine/placebo groups using mixed model analysis of variance procedures. Seroconversion did not differ by supplementation group (41.1% (94/229) with LNS vs. 39.1% (102/261) with multiple micronutrients (MMN) vs. 38.8% (118/304) with IFA, p = 0.91). Overall, 39.6% (n = 314/794) of infants who received vaccine seroconverted, compared to 29.0% (n = 212/731) of infants who received placebo (relative risk [RR]: 1.36; 95% confidence interval [CI]: 1.18, 1.57, p < 0.001). This study was conducted in a high rotavirus transmission setting. Study limitations include the absence of an immune correlate of protection for rotavirus vaccines, with the implications of using serum anti-rotavirus IgA for the assessment of immunogenicity and efficacy in low-income countries unclear.

CONCLUSIONS

This study showed no effect of the type of prenatal nutrient supplementation on immune response in this setting. Immune response varied depending on previous exposure to rotavirus, suggesting that alternative delivery modalities and schedules may be considered to improve vaccine performance in high transmission settings.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02145000.

Modified-Live Feline Calicivirus Vaccination Reduces Viral RNA Loads, Duration of RNAemia, and the Severity of Clinical Signs after Heterologous Feline Calicivirus Challenge

Feline calicivirus (FCV) is a common cat virus causing clinical signs such as oral ulcerations, fever, reduced general condition, pneumonia, limping and occasionally virulent-systemic disease. Efficacious FCV vaccines protect against severe disease but not against infection. FCV is a highly mutagenic RNA virus whose high genetic diversity poses a challenge in vaccine design. The use of only one modified-live FCV strain over several decades might have driven the viral evolution towards more vaccine-resistant variants. The present study investigated the clinical signs, duration, and amount of FCV shedding, RNAemia, haematological changes and acute phase protein reaction in SPF cats after subcutaneous modified-live single strain FCV vaccination or placebo injection and two subsequent oronasal heterologous FCV challenge infections with two different field strains. Neither clinical signs nor FCV shedding from the oropharynx and FCV RNAemia were detected after vaccination. After the first experimental infection, vaccinated cats had significantly lower clinical scores, less increased body temperature and lower acute phase protein levels than control cats. The viral RNA loads from the oropharynx and duration and amount of RNAemia were significantly lower in the vaccinated animals. No clinical signs were observed in any of the cats after the second experimental infection. In conclusion, FCV vaccination was beneficial for protecting cats from severe clinical signs, reducing viral loads and inflammation after FCV challenge.

Rotavirus vaccine efficacy up to 2 years of age and against diverse circulating rotavirus strains in Niger: Extended follow-up of a randomized controlled trial

BACKGROUND

Rotavirus vaccination is recommended in all countries to reduce the burden of diarrhea-related morbidity and mortality in children. In resource-limited settings, rotavirus vaccination in the national immunization program has important cost implications, and evidence for protection beyond the first year of life and against the evolving variety of rotavirus strains is important. We assessed the extended and strain-specific vaccine efficacy of a heat-stable, affordable oral rotavirus vaccine (Rotasiil, Serum Institute of India, Pune, India) against severe rotavirus gastroenteritis (SRVGE) among healthy infants in Niger.

METHODS AND FINDINGS

From August 2014 to November 2015, infants were randomized in a 1:1 ratio to receive 3 doses of Rotasiil or placebo at approximately 6, 10, and 14 weeks of age. Episodes of gastroenteritis were assessed through active and passive surveillance and graded using the Vesikari score. The primary endpoint was vaccine efficacy of 3 doses of vaccine versus placebo against a first episode of laboratory-confirmed SRVGE (Vesikari score ≥ 11) from 28 days after dose 3, as previously reported. At the time of the primary analysis, median age was 9.8 months. In the present paper, analyses of extended efficacy were undertaken for 3 periods (28 days after dose 3 to 1 year of age, 1 to 2 years of age, and the combined period 28 days after dose 3 to 2 years of age) and by individual rotavirus G type. Among the 3,508 infants included in the per-protocol efficacy analysis (mean age at first dose 6.5 weeks; 49% male), the vaccine provided significant protection against SRVGE through the first year of life (3.96 and 9.98 cases per 100 person-years for vaccine and placebo, respectively; vaccine efficacy 60.3%, 95% CI 43.6% to 72.1%) and over the entire efficacy follow-up period up to 2 years of age (2.13 and 4.69 cases per 100 person-years for vaccine and placebo, respectively; vaccine efficacy 54.7%, 95% CI 38.1% to 66.8%), but the difference was not statistically significant in the second year of life. Up to 2 years of age, rotavirus vaccination prevented 2.56 episodes of SRVGE per 100 child-years. Estimates of efficacy against SRVGE by individual rotavirus genotype were consistent with the overall protective efficacy. Study limitations include limited generalizability to settings with administration of oral polio virus due to low concomitant administration, limited power to assess vaccine efficacy in the second year of life owing to a low number of events among older children, potential bias due to censoring of placebo children at the time of study vaccine receipt, and suboptimal adapted severity scoring based on the Vesikari score, which was designed for use in settings with high parental literacy.

CONCLUSIONS

Rotasiil provided protection against SRVGE in infants through an extended follow-up period of approximately 2 years. Protection was significant in the first year of life, when the disease burden and risk of death are highest, and against a changing pattern of rotavirus strains during the 2-year efficacy period. Rotavirus vaccines that are safe, effective, and protective against multiple strains represent the best hope for preventing the severe consequences of rotavirus infection, especially in resource-limited settings, where access to care may be limited. Studies such as this provide valuable information for the planning of national immunization programs and future vaccine development.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02145000.

An inactivated recombinant rabies virus displaying the Zika virus prM-E induces protective immunity against both pathogens

The global spread of Zika virus (ZIKV), which caused a pandemic associated with Congenital Zika Syndrome and neuropathology in newborns and adults, prompted the pursuit of a safe and effective vaccine. Here, three kinds of recombinant rabies virus (RABV) encoding the prM-E protein of ZIKV were constructed: ZI-D (prM-E), ZI-E (transmembrane domain (TM) of prM-E replaced with RABV G) and ZI-F (signal peptide and TM domain of prM-E replaced with the region of RABV G). When the TM of prM-E was replaced with the region of RABV G (termed ZI-E), it promoted ZIKV E protein localization on the cell membrane and assembly on recombinant viruses. In addition, the change in the signal peptide with RABV G (termed ZI-F) was not conducive to foreign protein expression. The immunogenicity of recombinant viruses mixed with a complex adjuvant of ISA 201 VG and poly(I:C) was tested in BALB/c mice. After immunization with ZI-E, the anti-ZIKV IgG antibody lasted for at least 10 weeks. The titers of neutralizing antibodies (NAbs) against ZIKV and RABV at week 6 were all greater than the protective titers. Moreover, ZI-E stimulated the proliferation of splenic lymphocytes and promoted the secretion of cytokines. It also promoted the production of central memory T cells (TCMs) among CD4+/CD8+ T cells and stimulated B cell activation and maturation. These results indicate that ZI-E could induce ZIKV-specific humoral and cellular immune responses, which have the potential to be developed into a promising vaccine for protection against both ZIKV and RABV infections.

Pre-existing influenza-specific nasal IgA or nasal viral infection does not affect live attenuated influenza vaccine immunogenicity in children

The United Kingdom has a national immunization programme which includes annual influenza vaccination in school-aged children, using live attenuated influenza vaccine (LAIV). LAIV is given annually, and it is unclear whether repeat administration can affect immunogenicity. Because LAIV is delivered intranasally, pre-existing local antibody might be important. In this study, we analysed banked samples from a study performed during the 2017/18 influenza season to investigate the role of pre-existing influenza-specific nasal immunoglobulin (Ig)A in children aged 6-14 years. Nasopharyngeal swabs were collected prior to LAIV immunization to measure pre-existing IgA levels and test for concurrent upper respiratory tract viral infections (URTI). Oral fluid samples were taken at baseline and 21-28 days after LAIV to measure IgG as a surrogate of immunogenicity. Antibody levels at baseline were compared with a pre-existing data set of LAIV shedding from the same individuals, measured by reverse transcription-polymerase chain reaction. There was detectable nasal IgA specific to all four strains in the vaccine at baseline. However, baseline nasal IgA did not correlate with the fold change in IgG response to the vaccine. Baseline nasal IgA also did not have an impact upon whether vaccine virus RNA was detectable after immunization. There was no difference in fold change of antibody between individuals with and without an URTI at the time of immunization. Overall, we observed no effect of pre-existing influenza-specific nasal antibody levels on immunogenicity, supporting annual immunization with LAIV in children.

Efficacy of live attenuated and inactivated influenza vaccines among children in rural India: A 2-year, randomized, triple-blind, placebo-controlled trial

BACKGROUND

Influenza is a cause of febrile acute respiratory infection (FARI) in India; however, few influenza vaccine trials have been conducted in India. We assessed absolute and relative efficacy of live attenuated influenza vaccine (LAIV) and inactivated influenza vaccine (IIV) among children aged 2 to 10 years in rural India through a randomized, triple-blind, placebo-controlled trial conducted over 2 years.

METHODS AND FINDINGS

In June 2015, children were randomly allocated to LAIV, IIV, intranasal placebo, or inactivated polio vaccine (IPV) in a 2:2:1:1 ratio. In June 2016, vaccination was repeated per original allocation. Overall, 3,041 children received LAIV (n = 1,015), IIV (n = 1,010), nasal placebo (n = 507), or IPV (n = 509). Mean age of children was 6.5 years with 20% aged 9 to 10 years. Through weekly home visits, nasal and throat swabs were collected from children with FARI and tested for influenza virus by polymerase chain reaction. The primary outcome was laboratory-confirmed influenza-associated FARI; vaccine efficacy (VE) was calculated using modified intention-to-treat (mITT) analysis by Cox proportional hazards model (PH) for each year. In Year 1, VE was 40.0% (95% confidence interval (CI) 25.2 to 51.9) for LAIV and 59.0% (95% CI 47.8 to 67.9) for IIV compared with controls; relative efficacy of LAIV compared with IIV was -46.2% (95% CI -88.9 to -13.1). In Year 2, VE was 51.9% (95% CI 42.0 to 60.1) for LAIV and 49.9% (95% CI 39.2 to 58.7) for IIV; relative efficacy of LAIV compared with IIV was 4.2% (95% CI -19.9 to 23.5). No serious adverse vaccine-attributable events were reported. Study limitations include differing dosage requirements for children between nasal and injectable vaccines (single dose of LAIV versus 2 doses of IIV) in Year 1 and the fact that immunogenicity studies were not conducted.

CONCLUSIONS

In this study, we found that LAIV and IIV vaccines were safe and moderately efficacious against influenza virus infection among Indian children.

TRIAL REGISTRATION

Clinical Trials Registry of India CTRI/2015/06/005902.

Deficiency in CCR2 increases susceptibility of mice to infection with an intracellular pathogen, Francisella tularensis LVS, but does not impair development of protective immunity

CCR2 is the major chemokine receptor that regulates appropriate trafficking of inflammatory monocytes, but the role of this chemokine receptor and its ligands during primary and secondary infection with intracellular infections remains incompletely understood. Here we used murine infection with the Live Vaccine Strain (LVS) of Francisella tularensis to evaluate the role of CCR2 during primary and secondary parenteral responses to this prototype intracellular bacterium. We find that mice deficient in CCR2 are highly compromised in their ability to survive intradermal infection with LVS, indicating the importance of this receptor during primary parenteral responses. Interestingly, this defect could not be readily attributed to the activities of the known murine CCR2 ligands MCP-1/CCL2, MCP-3/CCL7, or MCP-5/CCL12. Nonetheless, CCR2 knockout mice vaccinated by infection with low doses of LVS generated optimal T cell responses that controlled the intramacrophage replication of Francisella, and LVS-immune CCR2 knockout mice survived maximal lethal Francisella challenge. Thus, fully protective adaptive immune memory responses to this intracellular bacterium can be readily generated in the absence of CCR2.

Systems Biology Analysis of the Radiation-Attenuated Schistosome Vaccine Reveals a Role for Growth Factors in Protection and Hemostasis Inhibition in Parasite Survival

In spite of several decades of research, an effective vaccine against schistosomiasis remains elusive. The radiation-attenuated (RA) cercarial vaccine is still the best model eliciting high protection levels, although the immune mechanisms have not yet been fully characterized. In order to identify genes and pathways underlying protection we investigated patterns of gene expression in PBMC and skin draining Lymph Nodes (LN) from mice using two exposure comparisons: vaccination with 500 attenuated cercariae versus infection with 500 normal cercariae; one versus three doses. Vaccinated mice were challenged with 120 normal parasites. Integration of PBMC and LN data from the infected group revealed early up-regulation of pathways associated with Th2 skewing and polarization of IgG antibody profiles. Additionally, hemostasis pathways were downregulated in infected mice, correlating with platelet reduction, potentially a mechanism to assist parasite migration through capillary beds. Conversely, up regulation of such mechanisms after vaccination may explain parasite blockade in the lungs. In contrast, a single exposure to attenuated parasites revealed early establishment of a Th1 bias (signaling of IL-1, IFN-γ; and Leishmania infection). Genes encoding chemokines and their receptors were more prominent in vaccinated mice, indicating an enhanced capacity for inflammation, potentially augmenting the inhibition of intravascular migration. Increasing the vaccinations from one to three did not dramatically elevate protection, but there was a clear shift towards antibody-mediated effectors. However, elements of the Th1 bias were still evident. Notable features after three vaccinations were markers of cytotoxicity (including IL-6 and NK cells) together with growth factors and their receptors (FGFR/VEGF/EGF) and the apoptosis pathway. Indeed, there is evidence for the development of anergy after three vaccinations, borne out by the limited responses detected in samples after challenge. We infer that persistence of a Th1 response puts a limit on expression of antibody-mediated mechanisms. This feature may explain the failure of multiple doses to drive protection towards sterile immunity. We suggest that the secretions of lung stage parasites would make a novel cohort of antigens for testing in protection experiments.

Adaptive immune responses in channel catfish exposed to Edwardsiella ictaluri live attenuated vaccine and wild type strains through the specific gene expression profiles

We extend the previous findings on the differential activity of immune-related genes in the lymphoid organs of channel catfish in the 7 days post-challenge (dpc) with E. ictaluri live attenuated vaccines (LAVs) and wild type (WT) strains by assessing the expression of these genes in the 21 dpc. The expression of T and B cell-specific genes were significantly elevated in the spleen at 14 dpc and in the AK at 21 dpc in catfish treated with E. ictaluri WT and LAV strains compared to a non-treated control group. The gene expression of IFN-γ correlated with adaptive immunity genes in the lymphoid tissues of catfish. These data indicate that two novel LAVs were able to trigger the activation of T helper1 polarization cytokine IFN-γ gene and specific lymphocyte genes in the spleen followed by their activation in the AK of catfish without causing inflammation, thus providing protective immunity in E. ictaluri infection.

A live attenuated Edwardsiella tarda vaccine induces immunological expression pattern in Japanese flounder (Paralichthys olivaceus) in the early phase of immunization

A previous study showed that an attenuated Edwardsiella tarda strain, TXhfq, as a live vaccine could elicit protective immune effects in fish against E. tarda infection. In the current study, in order to clarify the molecular mechanism of fish immune response at the early stage after TXhfq vaccination, RNA-Seq technology was used to compare the transcriptomes of skin, intestine, and spleen between bath-vaccinated and unvaccinated Japanese flounder (Paralichthys olivaceus). An average of 46.6 million clean reads per library was obtained, ~88.04% of which were successfully mapped to the reference genome, and approximately 24,600 genes were detected in each sample. A total of 565, 878, and 1258 differential expression genes (DEGs) were found in skin, intestine, and spleen, respectively, including 1263 up-regulated genes and 1438 down-regulated genes. The DEGs exhibited different characteristics in each tissue. One hundred and sixteen DEGs belonging to six immune related categories were scrutinized, i.e., inflammatory factors, cytokines, complement and coagulation system, mucins, phagocytosis, and antigen processing and presentation. A protein-protein interaction network was constructed to get the interaction network between immune genes during the early stage of immunization. The top six hub genes highly regulated by TXhfq formed complicated interaction relationship with each other, which were involved in immune processes, notably inflammation and phagocytosis. Our results provide valuable information for the understanding of the immune mechanism underlying the protection of live attenuated vaccines in fish.

Viral Subpopulation Screening Guides in Designing a High Interferon-Inducing Live Attenuated Influenza Vaccine by Targeting Rare Mutations in NS1 and PB2 Proteins

Influenza A viruses continue to circulate among wild birds and poultry worldwide, posing constant pandemic threats to humans. Effective control of emerging influenza viruses requires new broadly protective vaccines. Live attenuated influenza vaccines with truncations in nonstructural protein 1 (NS1) have shown broad protective efficacies in birds and mammals, which correlate with the ability to induce elevated interferon responses in the vaccinated hosts. Given the extreme diversity of influenza virus populations, we asked if we could improve an NS1-truncated live attenuated influenza vaccine developed for poultry (PC4) by selecting viral subpopulations with enhanced interferon-inducing capacities. Here, we deconstructed a de novo population of PC4 through plaque isolation, created a large library of clones, and assessed their interferon-inducing phenotypes. While most of the clones displayed the parental interferon-inducing phenotype in cell culture, few clones showed enhanced interferon-inducing phenotypes in cell culture and chickens. The enhanced interferon-inducing phenotypes were linked to either a deletion in NS1 (NS1Δ76-86) or a substitution in polymerase basic 2 protein (PB2-D309N). The NS1Δ76-86 deletion disrupted the putative eukaryotic translation initiation factor 4GI-binding domain and promoted the synthesis of biologically active interferons. The PB2-D309N substitution enhanced the early transcription of interferon mRNA, revealing a novel role for the 309D residue in suppression of interferon responses. We combined these mutations to engineer a novel vaccine candidate that induced additive amounts of interferons and stimulated protective immunity in chickens. Therefore, viral subpopulation screening approaches can guide the design of live vaccines with strong immunostimulatory properties.IMPORTANCE Effectiveness of NS1-truncated live attenuated influenza vaccines relies heavily on their ability to induce elevated interferon responses in vaccinated hosts. Influenza viruses contain diverse particle subpopulations with distinct phenotypes. We show that live influenza vaccines can contain underappreciated subpopulations with enhanced interferon-inducing phenotypes. The genomic traits of such virus subpopulations can be used to further improve the efficacy of the current live vaccines.

Current Advances in Burkholderia Vaccines Development

The genus Burkholderia includes a wide range of Gram-negative bacterial species some of which are pathogenic to humans and other vertebrates. The most pathogenic species are Burkholderia mallei, Burkholderia pseudomallei, and the members of the Burkholderia cepacia complex (Bcc). B. mallei and B. pseudomallei, the cause of glanders and melioidosis, respectively, are considered potential bioweapons. The Bcc comprises a subset of Burkholderia species associated with respiratory infections in people with chronic granulomatous disease and cystic fibrosis. Antimicrobial treatment of Burkholderia infections is difficult due to the intrinsic multidrug antibiotic resistance of these bacteria; prophylactic vaccines provide an attractive alternative to counteract these infections. Although commercial vaccines against Burkholderia infections are still unavailable, substantial progress has been made over recent years in the development of vaccines against B. pseudomallei and B. mallei. This review critically discusses the current advances in vaccine development against B. mallei, B. pseudomallei, and the Bcc.

Infectious RNA vaccine protects mice against chikungunya virus infection

We describe a novel vaccine platform that can generate protective immunity to chikungunya virus (CHIKV) in C57BL/6J mice after a single immunization by employing an infectious RNA (iRNA), which upon introduction into a host cell launches an infectious attenuated virus. We and others have previously reported that an engineered deletion of 183 nucleotides in the nsP3 gene attenuates chikungunya virus (CHIKV) and reduces in vivo viral replication and viremia after challenge in mice, macaques and man. Here, we demonstrated that in vitro transfection of iRNA carrying the nsP3 deletion generated infectious viruses, and after intramuscular injection, the iRNA induced robust antibody responses in mice. The iRNA was superior at eliciting binding and neutralizing antibody responses as compared to a DNA vaccine encoding the same RNA (iDNA) or a non-propagating RNA replicon (RREP) lacking the capsid encoding gene. Subsequent challenge with a high dose of CHIKV demonstrated that the antibody responses induced by this vaccine candidate protected animals from viremia. The iRNA approach constitutes a novel vaccine platform with the potential to impact the spread of CHIKV. Moreover, we believe that this approach is likely applicable also to other positive-strand viruses.

Post-vaccine rotavirus genotype distribution in Nairobi County, Kenya

BACKGROUND

Rotaviruses are primary etiological agents of gastroenteritis in young children. In Kenya, G1P8 monovalent vaccine (Rotarix) was introduced in July 2014 for mandatory vaccination of all newborns at 6 and 10 weeks of age. Since then, no studies have been done to identify the rotavirus genotypes circulating in Nairobi County, Kenya, following the vaccine introduction, hence the post-vaccine genotype distribution is not known.

OBJECTIVES

The aim of this study was to determine the post-vaccine occurrence of rotavirus genotypes in children <5 years of age in Nairobi County, Kenya.

METHODS

Stool samples were collected from children presenting with diarrhea for whom the vaccination status was card-confirmed. Fecal samples were analyzed for rotavirus antigen using a commercial enzyme immunoassay (EIA) kit, followed by characterization by polyacrylamide gel electrophoresis, RT-PCR, and nested PCR genotyping, targeting the most medically important genotypes.

RESULTS

The strains observed included G1P[8] (38.8%), G9P[8] (20.4%), G2P[4] (12.2%), G3[P4] (6.1%), G2P[6] (4.1%), and G9P[6] (4.1%). Mixed genotype constellations G3P[4][8] were also detected (4.1%). Remarkably, an increased prevalence of G2 genotypes was observed, revealing a change in genetic diversity of rotavirus strains. While the dominance of G1P[8] decreased after vaccination, an upsurge in G2P[4] (12.2%) and G9P[8] (20.4%) was observed. Additionally, G3[P4] (6.1%) and G2P[6] (4.1%) prevalence increased over the 3 years of study.

CONCLUSIONS

The results inform the need for robust longitudinal surveillance and epidemiological studies to assess the long-term interaction between rotavirus vaccine and strain ecology.

Evaluation of the antigen relatedness and efficacy of a single vaccination with different infectious bronchitis virus strains against a challenge with Malaysian variant and QX-like IBV strains

BACKGROUND

The predominant infectious bronchitis virus (IBV) strains detected in chickens in Malaysia are the Malaysian variant (MV) and QX-like, which are associated with respiratory distress, nephropathy, and high mortality. On the other hand, the antigenic relatedness and efficacy of IBV vaccines against these 2 field IBV strains are not well characterized.

OBJECTIVES

This study aimed to determine the antigen relatedness and efficacy of different IB vaccine strains against a challenge with MV and QX-like strains.

METHODS

The antigen relatedness and the ability of different IB vaccine strains in conferring protection against MV and QX-like were assessed based on the clinical signs, macroscopic lesions, and ciliary activity.

RESULTS

The MV strain IBS037A/2014 showed minor antigenic subtype differences with the vaccine virus Mass H120 and 4/91 strains but showed major antigenic subtype differences with the K2 strain. The Malaysian QX-like strain IBS130/2015 showed major antigenic subtype differences with the MV strain IBS037A/2014 and the vaccine strains except for K2. Chickens vaccinated once with Mass (H120) or with non-Mass (4/91 and K2) developed antibody responses with the highest antibody titer detected in the groups vaccinated with H120 and 4/91. The mean ciliary activities of the vaccinated chickens were between 56 to 59% and 48 to 52% in chickens challenged with IBS037A/2014 and IBS130/2015, respectively. The vaccinated and challenged birds showed mild to severe lesions in the lungs and kidneys.

CONCLUSIONS

Despite the minor antigenic subtype differences, a single inoculation with Mass or non-Mass vaccines could not protect against the MV IBS037A/2014 and QX-like IBS130/2015.

Historical discourse on the development of the live attenuated tetravalent dengue vaccine candidate TV003/TV005

Dengue is the most important arboviral disease world-wide with an estimated 400 million annual infections. Dengvaxia™ is a live attenuated tetravalent vaccine recently licensed for dengue seropositive individuals aged 9-45 years. There is great need for a dengue vaccine that could be given to dengue-naïve individuals and very young children. To that end, the U.S. NIH developed a live attenuated tetravalent dengue vaccine using an iterative approach evaluating the safety, infectivity, and immunogenicity of different candidates. This approach identified poor candidates who were then discarded from further evaluation. Each of the components of the tetravalent vaccine formulation is able to replicate to very low titer, inducing a homotypic immune response to each. The immune response elicited by the tetravalent vaccine is balanced, without immunodominance of one component. The vaccine was licensed by several manufacturers for development, including the Instituto Butantan which initiated a Phase 3 efficacy trial.

Japanese Encephalitis Virus Vaccination Elicits Cross-Reactive HLA-Class I-Restricted CD8 T Cell Response Against Zika Virus Infection

Japanese encephalitis virus (JEV) exposure or vaccination could elicit cross-reactive CD8 T cell immunity against heterologous flaviviruses in humans. In addition, cross-reactive CD8 T cells induced by dengue virus (DENV) have been shown to play a protective role against Zika virus (ZIKV). However, how JEV exposure or vaccination affects ZIKV infection in humans remains unclear. In this report, epitope prediction algorithms were used to predict the cross-reactive CD8 T cell epitope restricted to human HLA between JEV and ZIKV. We found that these predicted CD8 T cell epitopes are immunogenic and cross-reactive in humanized HLA transgenic mice. Moreover, JEV vaccine immunization provided cross-protection against ZIKV infection. Furthermore, CD8 T cells were involved in the protection against ZKIV infection in vivo. Our results have an important clinical implication that vaccination with JEV SA14-14-2 may provide protection against ZIKV infection in humans.

Stability of live attenuated classical swine fever cell culture vaccine virus in liquid form for developing an oral vaccine

Classical swine fever (CSF) is an important viral disease of pigs and controlled by vaccination. Unorganised backyard and wild pigs are difficult to vaccinate by needle vaccination. Here we formulated liquid vaccines using an Indian CSF cell culture vaccine virus and four stabilisers and evaluated their stability at 4 °C, 25 °C and 37 °C up to 24 h for use as oral vaccine. The stabilisers were Lactalbumin hydrolysate-Trehalose, Lactalbumin hydrolysate-Trehalose-Gelatin, Lactalbumin hydrolysate-Lactose-Sucrose and Lactalbumin hydrolysate-Sucrose. The liquid vaccines, with or without stabilisers, were stable at 4 °C up to 24 h, whereas, a drop of one log₁₀ titre was observed at 25 °C during the same period. At 37 °C, the virus titre diminished by only one log₁₀ with the Lactalbumin hydrolysate-Trehalose (LT) stabiliser up to 24 h compared to two log₁₀ losses in virus titre with other stabilisers and virus control. We therefore conclude that for developing a CSF oral vaccine, the vaccine virus in liquid form can be used directly during the winter, whereas for developing the oral vaccine for summer, the LT stabiliser would provide maximum stability to the virus to withstand the warm temperature while maintaining adequate therapeutic titre for inducing a protective immune response.

An effective live attenuated vaccine against Aeromonas veronii infection in the loach (Misgurnus anguillicaudatus)

Aeromonas veronii is a major pathogenic bacterium in humans and animals. When it causes outbreaks, there are enormous economic losses to the aquaculture industry. An effective live attenuated vaccine strain, ΔhisJ, was obtained in our previous studies by gene knockout in Aeromonas veronii TH0426 using the suicide vector pRE112. Here, we evaluated whether the live attenuated vaccine ΔhisJ was suitable for prevention of Aeromonas veronii infection by injection and immersion in loaches. Compared with that of the TH0426 wild-type strain, the virulence of the live vaccine was significantly weakened. Vaccine safety assessment results also indicated that 1 × 10⁷ CFU/mL live vaccine was safe and did not induce clinical symptoms or obvious pathological changes. Additionally, after challenging loaches with Aeromonas veronii TH0426, the relative percent survival of the IN3 injection group was 65.66%, and that of the IM group was 50.78%. Our data show that the live attenuated vaccine ΔhisJ can improve the immune protection rate of loaches. Furthermore, increased enzyme activity parameters (SOD, LZM, ACP, and AKP) in the skin mucus, increased enzyme activity parameters (SOD, LZM, ACP, AKP, and GPx) in the serum, increased specific IgM antibodies and cytokine IL-1β contents in the serum, and increased cytokine (IL-15, pIgR, IL-1β, and TNF-α) expression in the liver and spleen were observed. These data are the first to indicate that the live attenuated vaccine ΔhisJ is suitable for the development of a safe and effective vaccine against Aeromonas veronii infection in loach aquaculture.

A HSV1 mutant leads to an attenuated phenotype and induces immunity with a protective effect

Herpes simplex virus type 1 (HSV1) is a complicated structural agent with a sophisticated transcription process and a high infection rate. A vaccine against HSV1 is urgently needed. As multiple viral-encoded proteins, including structural and nonstructural proteins, contribute to immune response stimulation, an attenuated or deficient HSV1 vaccine may be relatively reliable. Advances in genomic modification technologies provide reliable means of constructing various HSV vaccine candidates. Based on our previous work, an M6 mutant with mutations in the UL7, UL41, LAT, Us3, Us11 and Us12 genes was established. The mutant exhibited low proliferation in cells and an attenuated phenotype in an animal model. Furthermore, in mice and rhesus monkeys, the mutant can induce remarkable serum neutralizing antibody titers and T cell activation and protect against HSV1 challenge by impeding viral replication, dissemination and pathogenesis.

Live attenuated Edwardsiella ictaluri vaccines enhance the protective innate immune responses of channel catfish B cells

Edwardsiella ictaluri causes enteric septicemia of catfish. Our group developed two E. ictaluri live attenuated vaccines (LAVs). However, their effects on the innate functions of catfish B cells are still unexplored. We evaluated phagocytosis and killing of wild-type (WT) E. ictaluri opsonized with sera from vaccinated fish and the survival of B cells exposed to E. ictaluri strains. We assessed phagocytosis of the opsonized WT at 30 °C and 4 °C. B cells killed the internalized E. ictaluri opsonized with sera from vaccinated fish with LAVs more efficiently than other groups at 30 °C. However, catfish B cells were unable to destroy E. ictaluri at 4 °C. Furthermore, E. ictaluri opsonized with serum from fish exposed to WT induce apoptosis and decreased live B cells numbers. Results indicate that opsonization of E. ictaluri with sera from vaccinated fish enhanced phagocytosis and killing activity in B cells and inhibited apoptotic changes in the infected B cells.

Evaluation of Cyclophosphamide/GVAX Pancreas Followed by Listeria-Mesothelin (CRS-207) with or without Nivolumab in Patients with Pancreatic Cancer

PURPOSE

Two studies in previously treated metastatic pancreatic cancer have been completed combining GVAX pancreas vaccine (GM-CSF-secreting allogeneic pancreatic tumor cells) with cyclophosphamide (Cy) and CRS-207 (live, attenuated Listeria monocytogenes-expressing mesothelin). In the current study, we compared Cy/GVAX followed by CRS-207 with (Arm A) or without nivolumab (Arm B).

PATIENTS AND METHODS

Patients with pancreatic adenocarcinoma who received one prior therapy for metastatic disease and RECIST measurable disease were randomized 1:1 to receive treatment on Arm A or Arm B. The primary objective was to compare overall survival (OS) between the arms. Additional objectives included assessment of progression-free survival, safety, tumor responses, CA19-9 responses, and immunologic correlates.

RESULTS

Ninety-three patients were treated (Arm A, 51; Arm B, 42). The median OS in Arms A and B were 5.9 [95% confidence interval (CI), 4.7-8.6] and 6.1 (95% CI, 3.5-7.0) months, respectively, with an HR of 0.86 (95% CI, 0.55-1.34). Objective responses were seen in 3 patients using immune-related response criteria (4%, 2/51, Arm A; 2%, 1/42, Arm B). The grade ≥3 related adverse event rate, whereas higher in Arm A (35.3% vs. 11.9%) was manageable. Changes in the microenvironment, including increase in CD8+ T cells and a decrease in CD68+ myeloid cells, were observed in long-term survivors in Arm A only.

CONCLUSIONS

Although the study did not meet its primary endpoint of improvement in OS of Arm A over Arm B, the OS was comparable with standard therapy. Objective responses and immunologic changes in the tumor microenvironment were evident.

Multi-antigen DNA vaccine delivered by polyethylenimine and Salmonella enterica in neuroblastoma mouse model

Neuroblastoma is an example of a difficult-to-treat tumor with high incidence of relapse. DNA vaccination could be applied as a relapse prophylactic option for patients with high-risk neuroblastoma. Its efficacy depends directly on a target antigen of choice and a delivery method. Three neuroblastoma-associated antigens (tyrosine hydroxylase, Survivin, PHOX2B) and two delivery methods were investigated. Our data suggest that antigen PHOX2B is a more immunogenic target that induces cellular immune response and tumor regression more effectively than tyrosine hydroxylase and Survivin. Immunogenicity testing revealed that the delivery of DNA vaccine by Salmonella enterica was accompanied by a stronger immune response (cytotoxicity and IFNγ production) than that by DNA-polyethylenimine conjugate. Nevertheless, intramuscular immunization with PEI led to higher decrease of tumor volume compared to that after oral gavage with Salmonella vaccine.

Experimental evaluation of the cross-protection between Sheeppox and bovine Lumpy skin vaccines

The Capripoxvirus genus includes three agents: Sheeppox virus, Goatpox virus and Lumpy skin disease virus. Related diseases are of economic importance and present a major constraint to animals and animal products trade in addition to mortality and morbidity. Attenuated vaccines against these diseases are available, but afforded cross-protection is controversial in each specie. In this study, groups of sheep, goats and cattle were vaccinated with Romania SPPV vaccine and challenged with corresponding virulent strains. Sheep and cattle were also vaccinated with Neethling LSDV vaccine and challenged with both virulent SPPV and LSDV strains. Animals were monitored by clinical observation, rectal temperature as well as serological response. The study showed that sheep and goats vaccinated with Romania SPPV vaccine were fully protected against challenge with virulent SPPV and GTPV strains, respectively. However, small ruminants vaccinated with LSDV Neethling vaccine showed only partial protection against challenge with virulent SPPV strain. Cattle showed also only partial protection when vaccinated with Romania SPPV and were fully protected with Neethling LSDV vaccine. This study showed that SPPV and GTPV vaccines are closely related with cross-protection, while LSDV protects only cattle against the corresponding disease, which suggests that vaccination against LSDV should be carried out with homologous strain.

Phenotypic and Genotypic Comparison of a Live-Attenuated Genotype I Japanese Encephalitis Virus SD12-F120 Strain with Its Virulent Parental SD12 Strain

The phenotypic and genotypic characteristics of a live-attenuated genotype I (GI) strain (SD12-F120) of Japanese encephalitis virus (JEV) were compared with its virulent parental SD12 strain to gain an insight into the genetic changes acquired during the attenuation process. SD12-F120 formed smaller plaque on BHK-21 cells and showed reduced replication in mouse brains compared with SD12. Mice inoculated with SD12-F120 via either intraperitoneal or intracerebral route showed no clinical symptoms, indicating a highly attenuated phenotype in terms of both neuroinvasiveness and neurovirulence. SD12-F120 harbored 29 nucleotide variations compared with SD12, of which 20 were considered silent nucleotide mutations, while nine resulted in eight amino acid substitutions. Comparison of the amino acid variations of SD12-F120 vs. SD12 pair with those from other four isogenic pairs of the attenuated and their virulent parental strains revealed that the variations at E¹³⁸ and E¹⁷⁶ positions of E protein were identified in four and three pairs, respectively, while the remaining amino acid variations were almost unique to their respective strain pairs. These observations suggest that the genetic changes acquired during the attenuation process were likely to be strain-specific and that the mechanisms associated with JEV attenuation/virulence are complicated.

Tracking of an Oral Salmonella-Based Vaccine for Type 1 Diabetes in Non-obese Diabetic Mice

Type 1 diabetes (T1D) arises secondary to immune-driven destruction of pancreatic β-cells and manifests as insulin-deficient hyperglycemia. We showed that oral vaccination with live attenuated Salmonella, which simultaneously delivers autoantigens and a TGFβ expression vector to immune cells in the gut mucosa, provides protection against the progression of T1D in non-obese diabetic (NOD) mice. In this study we employed the Sleeping Beauty (SB) transposon system that is composed of a transposase and transposon encoding the td-Tomato to express red fluorescent protein (RFP) to permanently mark the cells that take up the Salmonella vaccine. After animal vaccination, the transposon labeled-dendritic cells (DCs) with red fluorescence appeared throughout the secondary lymphoid tissues. Furthermore, Sleeping Beauty containing tgfβ1 gene (SB-tgfβ1) co-expressed TGFβ and RFP. The labeled DCs were detected predominantly in Peyer's patches (PP) and mesenteric lymph nodes (MLN) and expressed CD103 surface marker. CD103+ DCs induced tolerogenic effects and gut homing. TGFβ significantly increased programmed death-ligand-1 (PDL-1 or CD274) expression in the DCs in the MLN and PP of treated mice. Also, TGFβ increased cytotoxic T-lymphocyte-associated protein-4 (CTLA-4) levels in CD4+ cells in MLN and PP. Interestingly, DCs increased in all lymphatic organs of mice vaccinated with oral live Salmonella-based vaccine expressing preproinsulin (PPI), in combination with TGFβ, IL10, and subtherapeutic-doses of anti-CD3 mAb compared with vehicle-treated mice. These DCs are mostly tolerogenic in MLN and PP. Furthermore the DCs obtained from vaccine-treated but not vehicle-treated mice suppressed in vitro T cell proliferation. These data suggest that the MLN and the PP are a central hub for the beneficial anti-diabetic effects of an oral Salmonella-based vaccine prevention of diabetes in rodents.

Evidence of rotavirus vaccine impact in sub-Saharan Africa: Systematic review and meta-analysis

BACKGROUND

Over 34 countries in Africa have introduced rotavirus vaccine to their national immunization programs: monovalent (Rotarix®, RV1) and pentavalent (RotaTeq®, RV5) after South Africa introduced it in 2009. Since then several studies assessing the impact of the vaccine have been conducted. The principal aim of this study was to evaluate the impact of rotavirus vaccine in sub-Saharan Africa.

METHODS

A Literature search was performed using Mendeley, PubMed, ScienceDirect, grey literature and Web of Science databases of published studies from January 1, 2017, as years of recent publications on rotavirus vaccine impact in sub-Saharan Africa. A meta-analysis was conducted for rotavirus infection in children under 5 years using proportions of pre and post-vaccine introduction in these populations. Random-effect estimates were considered since the samples were from universal populations.

RESULTS

Out of the 935 articles identified, 17 studies met the inclusion for systematic review and meta-analysis. The pooled proportion for pre-vaccination period was 42%, 95% (CI: 38-46%), and reduced to 21%, 95% (CI: 17-25%) during post-vaccination period. Rotavirus diarrhea significantly reduced in children < 12 months as compared to children 12-24 months old. Seasonal peaks of rotavirus diarrhea were between June-September. However, data is limited to one year of post-vaccine introduction, and bias may present due to early vaccine impact.

CONCLUSION

We observed that the introduction of the rotavirus vaccine was partly responsible for the significant reduction in the burden of rotavirus-associated diarrhea in sub-Saharan Africa. Therefore, there is a need to encourage the remaining countries to introduce the vaccine to their routine national immunization programs.

Vaccines for measles, mumps, rubella, and varicella in children

BACKGROUND

Measles, mumps, rubella, and varicella (chickenpox) are serious diseases that can lead to serious complications, disability, and death. However, public debate over the safety of the trivalent MMR vaccine and the resultant drop in vaccination coverage in several countries persists, despite its almost universal use and accepted effectiveness. This is an update of a review published in 2005 and updated in 2012.

OBJECTIVES

To assess the effectiveness, safety, and long- and short-term adverse effects associated with the trivalent vaccine, containing measles, rubella, mumps strains (MMR), or concurrent administration of MMR vaccine and varicella vaccine (MMR+V), or tetravalent vaccine containing measles, rubella, mumps, and varicella strains (MMRV), given to children aged up to 15 years.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library 2019, Issue 5), which includes the Cochrane Acute Respiratory Infections Group's Specialised Register, MEDLINE (1966 to 2 May 2019), Embase (1974 to 2 May 2019), the WHO International Clinical Trials Registry Platform (2 May 2019), and ClinicalTrials.gov (2 May 2019).

SELECTION CRITERIA

We included randomised controlled trials (RCTs), controlled clinical trials (CCTs), prospective and retrospective cohort studies (PCS/RCS), case-control studies (CCS), interrupted time-series (ITS) studies, case cross-over (CCO) studies, case-only ecological method (COEM) studies, self-controlled case series (SCCS) studies, person-time cohort (PTC) studies, and case-coverage design/screening methods (CCD/SM) studies, assessing any combined MMR or MMRV / MMR+V vaccine given in any dose, preparation or time schedule compared with no intervention or placebo, on healthy children up to 15 years of age.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the methodological quality of the included studies. We grouped studies for quantitative analysis according to study design, vaccine type (MMR, MMRV, MMR+V), virus strain, and study settings. Outcomes of interest were cases of measles, mumps, rubella, and varicella, and harms. Certainty of evidence of was rated using GRADE.

MAIN RESULTS

We included 138 studies (23,480,668 participants). Fifty-one studies (10,248,159 children) assessed vaccine effectiveness and 87 studies (13,232,509 children) assessed the association between vaccines and a variety of harms. We included 74 new studies to this 2019 version of the review. Effectiveness Vaccine effectiveness in preventing measles was 95% after one dose (relative risk (RR) 0.05, 95% CI 0.02 to 0.13; 7 cohort studies; 12,039 children; moderate certainty evidence) and 96% after two doses (RR 0.04, 95% CI 0.01 to 0.28; 5 cohort studies; 21,604 children; moderate certainty evidence). The effectiveness in preventing cases among household contacts or preventing transmission to others the children were in contact with after one dose was 81% (RR 0.19, 95% CI 0.04 to 0.89; 3 cohort studies; 151 children; low certainty evidence), after two doses 85% (RR 0.15, 95% CI 0.03 to 0.75; 3 cohort studies; 378 children; low certainty evidence), and after three doses was 96% (RR 0.04, 95% CI 0.01 to 0.23; 2 cohort studies; 151 children; low certainty evidence). The effectiveness (at least one dose) in preventing measles after exposure (post-exposure prophylaxis) was 74% (RR 0.26, 95% CI 0.14 to 0.50; 2 cohort studies; 283 children; low certainty evidence). The effectiveness of Jeryl Lynn containing MMR vaccine in preventing mumps was 72% after one dose (RR 0.24, 95% CI 0.08 to 0.76; 6 cohort studies; 9915 children; moderate certainty evidence), 86% after two doses (RR 0.12, 95% CI 0.04 to 0.35; 5 cohort studies; 7792 children; moderate certainty evidence). Effectiveness in preventing cases among household contacts was 74% (RR 0.26, 95% CI 0.13 to 0.49; 3 cohort studies; 1036 children; moderate certainty evidence). Vaccine effectiveness against rubella is 89% (RR 0.11, 95% CI 0.03 to 0.42; 1 cohort study; 1621 children; moderate certainty evidence). Vaccine effectiveness against varicella (any severity) after two doses in children aged 11 to 22 months is 95% in a 10 years follow-up (rate ratio (rr) 0.05, 95% CI 0.03 to 0.08; 1 RCT; 2279 children; high certainty evidence). Safety There is evidence supporting an association between aseptic meningitis and MMR vaccines containing Urabe and Leningrad-Zagreb mumps strains, but no evidence supporting this association for MMR vaccines containing Jeryl Lynn mumps strains (rr 1.30, 95% CI 0.66 to 2.56; low certainty evidence). The analyses provide evidence supporting an association between MMR/MMR+V/MMRV vaccines (Jeryl Lynn strain) and febrile seizures. Febrile seizures normally occur in 2% to 4% of healthy children at least once before the age of 5. The attributable risk febrile seizures vaccine-induced is estimated to be from 1 per 1700 to 1 per 1150 administered doses. The analyses provide evidence supporting an association between MMR vaccination and idiopathic thrombocytopaenic purpura (ITP). However, the risk of ITP after vaccination is smaller than after natural infection with these viruses. Natural infection of ITP occur in 5 cases per 100,000 (1 case per 20,000) per year. The attributable risk is estimated about 1 case of ITP per 40,000 administered MMR doses. There is no evidence of an association between MMR immunisation and encephalitis or encephalopathy (rate ratio 0.90, 95% CI 0.50 to 1.61; 2 observational studies; 1,071,088 children; low certainty evidence), and autistic spectrum disorders (rate ratio 0.93, 95% CI 0.85 to 1.01; 2 observational studies; 1,194,764 children; moderate certainty). There is insufficient evidence to determine the association between MMR immunisation and inflammatory bowel disease (odds ratio 1.42, 95% CI 0.93 to 2.16; 3 observational studies; 409 cases and 1416 controls; moderate certainty evidence). Additionally, there is no evidence supporting an association between MMR immunisation and cognitive delay, type 1 diabetes, asthma, dermatitis/eczema, hay fever, leukaemia, multiple sclerosis, gait disturbance, and bacterial or viral infections.

AUTHORS' CONCLUSIONS

Existing evidence on the safety and effectiveness of MMR/MMRV vaccines support their use for mass immunisation. Campaigns aimed at global eradication should assess epidemiological and socioeconomic situations of the countries as well as the capacity to achieve high vaccination coverage. More evidence is needed to assess whether the protective effect of MMR/MMRV could wane with time since immunisation.

Cutting Edge: Antitumor Immunity by Pathogen-Specific CD8 T Cells in the Absence of Cognate Antigen Recognition

Cancer prognosis often correlates with the number of tumor-infiltrating CD8 T cells, but many of these cells recognize pathogens that commonly infect humans. The contribution of pathogen-specific "bystander" CD8 T cells to antitumor immunity remains largely unknown. Inflammatory cytokines are sufficient for memory CD8 T cell activation and gain of effector functions, indicating tumor-derived inflammation could facilitate pathogen-specific CD8 T cells to participate in tumor control. In this study, we show in contrast to tumor-specific CD8 T cells that pathogen-specific primary memory CD8 T cells inside tumor were not able to exert their effector functions and influence tumor progression. However, infection-induced memory CD8 T cells with defined history of repeated Ag encounters (i.e., quaternary memory) showed increased sensitivity to tumor-derived inflammation that resulted in activation, gain of effector functions, and better control of tumor growth. Thus, memory CD8 T cells with heightened ability to recognize environmental inflammatory stimuli can contribute to antitumor immunity in the absence of cognate Ag recognition.

Immunotherapy with DNA vaccine and live attenuated rubella/SIV gag vectors plus early ART can prevent SIVmac251 viral rebound in acutely infected rhesus macaques

Anti-retroviral therapy (ART) has been highly successful in controlling HIV replication, reducing viral burden, and preventing both progression to AIDS and viral transmission. Yet, ART alone cannot cure the infection. Even after years of successful therapy, ART withdrawal leads inevitably to viral rebound within a few weeks or months. Our hypothesis: effective therapy must control both the replicating virus pool and the reactivatable latent viral reservoir. To do this, we have combined ART and immunotherapy to attack both viral pools simultaneously. The vaccine regimen consisted of DNA vaccine expressing SIV Gag, followed by a boost with live attenuated rubella/gag vectors. The vectors grow well in rhesus macaques, and they are potent immunogens when used in a prime and boost strategy. We infected rhesus macaques by high dose mucosal challenge with virulent SIVmac251 and waited three days to allow viral dissemination and establishment of a reactivatable viral reservoir before starting ART. While on ART, the control group received control DNA and empty rubella vaccine, while the immunotherapy group received DNA/gag prime, followed by boosts with rubella vectors expressing SIV gag over 27 weeks. Both groups had a vaccine "take" to rubella, and the vaccine group developed antibodies and T cells specific for Gag. Five weeks after the last immunization, we stopped ART and monitored virus rebound. All four control animals eventually had a viral rebound, and two were euthanized for AIDS. One control macaque did not rebound until 2 years after ART release. In contrast, there was only one viral rebound in the vaccine group. Three out of four vaccinees had no viral rebound, even after CD8 depletion, and they remain in drug-free viral remission more than 2.5 years later. The strategy of early ART combined with immunotherapy can produce a sustained SIV remission in macaques and may be relevant for immunotherapy of HIV in humans.

Construction and evaluation of Vibrio alginolyticus ΔclpP mutant, as a safe live attenuated vibriosis vaccine

Vibrio alginolyticus is a common and serious pathogen threatening the progress of coastal aquaculture. ClpP protease has been proved to be closely associated with biofilm formation, stress tolerance, autolysis and virulence in several pathogens. Hence, targeting ClpP may be a potentially viable, attractive option for the preparation of vaccine in preventing vibriosis. In this study, an in-frame deleted mutant strain (ΔclpP) was constructed by allelic exchange mutagenesis to investigate physiological role of clpP in pathogenicity of V. alginolyticus and evaluate its potential as a live attenuated vaccine. The results exhibited that ΔclpP showed no differences in external morphology, growth, swarming motility and ECPase activity. However, ΔclpP represented an increment in biofilm formation, and a decrement in adherence to CIK cells. In addition, virulence of ΔclpP was examined in pearl gentian grouper and was found to be seriously attenuated. ΔclpP induced high antibody titers and provided a valid protection with a relative percent survival value of 83.8% without histopathologic abnormality. Our results indicated ΔclpP showed a great potential to be a live attenuated vaccine.

Profiling the transcriptome response of Atlantic salmon head kidney to formalin-killed Renibacterium salmoninarum

Renibacterium salmoninarum is a Gram-positive, intracellular bacterial pathogen that causes Bacterial Kidney Disease (BKD) in Atlantic salmon (Salmo salar). The host transcriptomic response to this immune-suppressive pathogen remains poorly understood. To identify R. salmoninarum-responsive genes, Atlantic salmon were intraperitoneally injected with a low (5 × 10⁵ cells/kg, Low-Rs) or high (5 × 10⁷ cells/kg; High-Rs) dose of formalin-killed R. salmoninarum bacterin or phosphate-buffered saline (PBS control); head kidney samples were collected before and 24 h after injection. Using 44K microarray analysis, we identified 107 and 345 differentially expressed probes in response to R. salmoninarum bacterin (i.e. High-Rs vs. PBS control) by Significance Analysis of Microarrays (SAM) and Rank Products (RP), respectively. Twenty-two microarray-identified genes were subjected to qPCR assays, and 17 genes were confirmed as being significantly responsive to the bacterin. There was an up-regulation in expression of genes playing putative roles as immune receptors and antimicrobial effectors. Genes with putative roles as pathogen recognition (e.g. clec12b and tlr5) or immunoregulatory (e.g. tnfrsf6b and tnfrsf11b) receptors were up-regulated in response to R.salmoninarum bacterin. Also, chemokines and a chemokine receptor showed opposite regulation [up-regulation of effectors (i.e. ccl13 and ccl) and down-regulation of cxcr1] in response to the bacterin. The present study identified and validated novel biomarker genes (e.g. ctsl1, lipe, cldn4, ccny) that can be used to assess Atlantic salmon response to R. salmoninarum, and will be valuable in the development of tools to combat BKD.

An effective live attenuated vaccine against Streptococcus agalactiae infection in farmed Nile tilapia (Oreochromis niloticus)

Streptococcus agalactiae is an important pathogen associated with various aquatic animals, especially tilapia. Streptococcosis has greatly limited the healthy development of tilapia aquaculture in recent times. The development of novel effective vaccines is important for the prevention and control of streptococcosis in fish. We previously constructed a non-encapsulated S. agalactiae strain △cps by the in-frame deletion method. Here, we evaluated whether this mutant △cps is safe for tilapia and suitable for protection against streptococcosis. We observed that the △cps strain was non-pathogenic to tilapia, and there was no reversion of virulence when it was passaged in tilapia. Moreover, the △cps strain survived for at least 11 d in the main immune organs of tilapia. The tilapia vaccinated via intraperitoneal (IP) injection with △cps strain induced a high antibody titer, and the IgM antibody levels were significantly higher in the vaccinated group than in the control group. The vaccination protected tilapia against the S. agalactiae challenge with a relative percent survival of 90.47%. In addition, tilapia immunized with the △cps strain showed significantly higher expression level of IFN-γ, IL-1β, MyD88, IgM, and MHC-Iα in the head kidney than those in the control during the entire observation period. The expression of MHC-IIβ was inhibited during 1-7 d of immunization. These results revealed that the △cps strain is able to induce humoral and cell-mediated immune response in tilapia. Therefore, the strain △cps has a broad application prospect as a target for attenuation in vaccine development.

Safety of inadvertent administration of live zoster vaccine to immunosuppressed individuals in a UK-based observational cohort analysis

OBJECTIVES

To investigate the safety of live attenuated varicella zoster vaccination when administered to immunosuppressed individuals.

DESIGN

Prospective observational cohort study.

SETTING

The study used anonymised data from the Clinical Practice Research Datalink (CPRD), comprising a representative sample of routinely collected primary care data in England between 2013 and 2017 and and linked Hospital Episode Statistics data.

PARTICIPANTS

168 767 individuals age-eligible for varicella zoster vaccination registered at a general practice in England contributing data to CPRD.

MAIN OUTCOME MEASURES

Electronic health records indicating immunosuppression, zoster vaccination, diagnoses of specific varicella-zoster virus (VZV)-related disease and non-specific rash/encephalitis compatible with VZV-related disease.

RESULTS

Between 1 September 2013 and 31 August 2017, a period of immunosuppression was identified for 9093/168 767 (5.4%; 95% CI: 5.3%-5.5%) individuals age-eligible for zoster vaccination. The overall rate of vaccination while immunosuppressed was 1742/5251 (33.2 per 100 adjusted person years at risk; 95% CI: 31.9%-34.5%). Follow-up of the 1742 individuals who were inadvertently vaccinated while immunosuppressed identified only two cases of VZV-related disease within 8 weeks of vaccination (0.1%; 95% CI: 0.01%-0.4%), both primary care diagnoses of 'shingles', neither with a related hospital admission.

CONCLUSIONS

Despite evidence of inadvertent vaccination of immunosuppressed individuals with live zoster vaccination, there is a lack of evidence of severe consequences including hospitalisation. This should reassure primary care staff and encourage vaccination of mildly immunosuppressed individuals who do not meet current thresholds for contraindication. These findings support a review of the extent to which live zoster vaccination is contraindicated among the immunosuppressed.

Subcutaneous vaccination with a live attenuated Yersinia pseudotuberculosis plague vaccine

A single oral inoculation to mice of the live attenuated Yersinia pseudotuberculosis VTnF1 strain producing an F1 pseudocapsule protects against bubonic and pneumonic plague. However oral vaccination can fail in humans exposed to frequent intestinal infections. We evaluated in mice the efficacy of subcutaneous vaccine injection as an alternative way to induce protective immunity, while reducing the dose and avoiding strain release in nature. A single subcutaneous dose of up to 10⁸ CFU induced dose-dependent antibody production. At the dose of 10⁷ CFU, i.e. 10 times less than via the oral route, it caused a modest skin reaction and protected 100% against bubonic and 80% against pneumonic plague, caused by high doses of Yersinia pestis. Bacteria migrating to lymph nodes and spleen, but not feces, were rapidly eliminated. Thus, subcutaneous injection of VTnF1 would represent a good alternative when dissemination in nature and human intestinal responsiveness are limitations.

In vivo rescue of recombinant Zika virus from an infectious cDNA clone and its implications in vaccine development

Zika virus (ZIKV) is a mosquito-borne member of the Flaviviridae family that has been known to circulate for decades causing mild febrile illness. The more recent ZIKV outbreaks in the Americas and the Caribbean associated with congenital malformations and Guillain-Barré syndrome in adults have placed public health officials in high alert and highlight the significant impact of ZIKV on human health. New technologies to study the biology of ZIKV and to develop more effective prevention options are highly desired. In this study we demonstrate that direct delivery in mice of an infectious ZIKV cDNA clone allows the rescue of recombinant (r)ZIKV in vivo. A bacterial artificial chromosome containing the sequence of ZIKV strain Paraiba/2015 under the control of the cytomegalovirus promoter was complexed with a commercial transfection reagent and administrated using different routes in type-I interferon receptor deficient A129 mice. Clinical signs and death associated with ZIKV viremia were observed in mice. The rZIKV recovered from these mice remained fully virulent in a second passage in mice. Interestingly, infectious rZIKV was also recovered after intraperitoneal inoculation of the rZIKV cDNA in the absence of transfection reagent. Further expanding these studies, we demonstrate that a single intraperitoneal inoculation of a cDNA clone encoding an attenuated rZIKV was safe, highly immunogenic, and provided full protection against lethal ZIKV challenge. This novel in vivo reverse genetics method is a potentially suitable delivery platform for the study of wild-type and live-attenuated ZIKV devoid of confounding factors typical associated with in vitro systems. Moreover, our results open the possibility of employing similar in vivo reverse genetic approaches for the generation of other viruses and, therefore, change the way we will use reverse genetics in the future.

Current and future cholera vaccines

Cholera remains a major global public health problem that is primarily linked to insufficient access to safe water and proper sanitation. Oral Cholera Vaccine (OCV) has been recommended as an additional public health tool along with WASH in cholera endemic countries and in areas at risk for outbreaks. The new generation OCV is safe and offers good protection in older children and adults while limited protection in younger children less than five years of age has been observed. The combination of direct vaccine protection and vaccine herd immunity effects makes OCV highly cost-effective and, therefore, attractive for use in developing countries. Additionally, in recent studies OCV was safe in pregnant women, supporting its use in pregnant women in cholera endemic countries. However, knowledge need to be developed for current vaccines for their prolonged duration of protection and vaccines need improvements for better immune response in younger children. A single dose vaccination regimen would be more cost-effective and easier to deliver. Recent approaches have focused on designing genetically attenuated cholera strains for use in single-dose cholera vaccines. The global demand for OCV has been boosted by the WHO recommendation to use OCV and is driven largely by epidemics and outbreaks and has been increasing due to the availability of cheaper easy-to-use vaccines, feasibility of mass OCV vaccination campaigns, demonstration of protection to underserved population in precarious situations, and vaccine costs being borne by Gavi (Vaccine Alliance). For rapid access in emergency and equitable distribution of OCV in cholera-endemic low-income countries, a global OCV stockpile was established in 2013 with support from the Global Alliance for Vaccines and Immunization. The three WHO-prequalified vaccines are Dukoral®, Shanchol™, Euvichol® (and Euvichol® Plus presentation), the latter two being included in the stockpile.

Immunogenicity, safety, and tolerability of the measles-vectored chikungunya virus vaccine MV-CHIK: a double-blind, randomised, placebo-controlled and active-controlled phase 2 trial

BACKGROUND

Chikungunya fever is an emerging viral disease and substantial threat to public health. We aimed to assess the safety, tolerability, and immunogenicity of a live-attenuated, measles-vectored chikungunya vaccine (MV-CHIK).

METHODS

In this double-blind, randomised, placebo-controlled and active-controlled phase 2 trial, we enrolled healthy volunteers aged 18-55 years at four study sites in Austria and Germany. Participants were randomly assigned to receive intramuscular injections with MV-CHIK (5 × 10⁴ or 5 × 10⁵ 50% tissue culture infectious dose), control vaccine, or measles prime and MV-CHIK, in two different administration regimens. Randomisation was done by use of three-digit randomisation codes in envelopes provided by a data management service. The participants and investigators were masked to treatment assignment, which was maintained by use of sterile saline as a placebo injection. The primary endpoint was immunogenicity, defined as the presence of neutralising antibodies against chikungunya virus, at day 56, which is 28 days after one or two immunisations. The primary endpoint was assessed in all participants who completed the study without major protocol deviations (per-protocol population) and in all randomised participants who received at least one study treatment (modified intention-to-treat population). The safety analysis included all participants who received at least one study treatment. This trial is registered with ClinicalTrials.gov (NCT02861586) and EudraCT (2015-004037-26) and is completed.

FINDINGS

Between Aug 17, 2016, and May 31, 2017, we randomly assigned 263 participants to receive control vaccine (n=34), MV-CHIK (n=195), or measles prime and MV-CHIK (n=34). 247 participants were included in the per-protocol population. Neutralising antibodies against chikungunya virus were detected in all MV-CHIK treatment groups after one or two immunisations, with geometric mean titres ranging from 12·87 (95% CI 8·75-18·93) to 174·80 (119·10-256·50) and seroconversion rates ranging from 50·0% to 95·9% depending on the dose and administration schedule. Adverse events were similar between groups, with solicited adverse events reported in 168 (73%) of 229 participants assigned to MV-CHIK and 24 (71%) of 34 assigned to control vaccine (p=0·84) and unsolicited adverse events in 116 (51%) participants assigned to MV-CHIK and 17 (50%) assigned to control vaccine (p=1·00). No serious adverse events related to the vaccine were reported.

INTERPRETATION

MV-CHIK showed excellent safety and tolerability and good immunogenicity, independent of pre-existing immunity against the vector. MV-CHIK is a promising candidate vaccine for the prevention of chikungunya fever, an emerging disease of global concern.

FUNDING

Themis.

Vaccine or field strains: the jigsaw pattern of infectious bronchitis virus molecular epidemiology in Poland

Infectious bronchitis (IB), caused by infectious bronchitis virus (IBV), account for severe economic losses in the poultry industry. The continuous emergence of a multitude of IBV variants poses many challenges for its diagnosis and control, and live attenuated vaccines, despite their routine use, still plays a significant role in driving IBV evolution, further complicating the epidemiological scenario. Unfortunately, the impact of different vaccination strategies on IB control, epidemiology, and diagnosis has rarely been investigated. This work presents the results of a large-scale diagnostic survey performed in Poland to study IBV molecular epidemiology and how vaccination may affect the viral circulation in the field. To this purpose, 589 samples were collected between May 2017 and January 2019, tested by reverse transcription-PCR for IBV and sequenced. Vaccine and field strains were discriminated based on genetic and anamnestic information. The most commonly detected lineages were 793B (79%) and variant 2 (17.4%), with sporadic detections of QX, Mass, and D274-like strains. Most of the detected strains had a vaccine origin: 46.3% matched one of the applied vaccines, while 36.5% were genetically related to vaccines not implemented in the respective protocol. Besides their practical value for the proper planning of vaccination protocols in Poland, these results suggest that only a fraction (17.2%) of the circulating strains are field ones, imposing a careful assessment of the actual IBV field menaces. Moreover, phenomena like vaccine spreading and persistence seem to occur commonly, stressing the need to further study the epidemiological consequences of the extensive use of live vaccines.

The ORVAC trial protocol: a phase IV, double-blind, randomised, placebo-controlled clinical trial of a third scheduled dose of Rotarix rotavirus vaccine in Australian Indigenous infants to improve protection against gastroenteritis

INTRODUCTION

Rotavirus vaccines were introduced into the Australian National Immunisation Program in 2007. Despite this, Northern Territory Indigenous children continue to be hospitalised with rotavirus at a rate more than 20 times higher than non-Indigenous children in other Australian jurisdictions, with evidence of waning protection in the second year of life. We hypothesised that scheduling an additional (third) dose of oral human rotavirus vaccine (Rotarix, GlaxoSmithKline) for children aged 6 to <12 months would improve protection against clinically significant all-cause gastroenteritis.

METHODS AND ANALYSIS

This Bayesian adaptive clinical trial will investigate whether routinely scheduling an additional dose of Rotarix for Australian Indigenous children aged 6 to <12 months old confers significantly better protection against clinically important all-cause gastroenteritis than the current two-dose schedule at 2 and 4 months old. There are two coprimary endpoints: (1) seroconversion from baseline serum anti-rotavirus immunoglobulin A (IgA) titre <20 U/mL prior to an additional dose of Rotarix/placebo to serum anti-rotavirus IgA titre >20 U/mL following the administration of the additional dose of Rotarix/placebo and (2) time from randomisation to medical attendance (up to age 36 months old) for which the primary reason is acute gastroenteritis/diarrhoea. Secondary endpoints include the change in anti-rotavirus IgA log titre, time to hospitalisation for all-cause diarrhoea and for rotavirus-confirmed gastroenteritis/diarrhoea, and rotavirus notification. Analysis will be based on Bayesian inference with adaptive sample size.

ETHICS, REGISTRATION AND DISSEMINATION

Ethics approval has been granted by Central Australian Human Research Ethics Committee (HREC-16-426) and Human Research Ethics Committee of the Northern Territory Department of Health and Menzies School of Health Research (HREC-2016-2658). Study investigators will ensure the trial is conducted in accordance with the principles of the Declaration of Helsinki and with the ICH Guidelines for Good Clinical Practice. Individual participant consent will be obtained. Results will be disseminated via peer-reviewed publication. The trial is registered with Clinicaltrials.gov (NCT02941107) and important modifications to this protocol will be updated.

TRIAL REGISTRATION NUMBER

NCT02941107; Pre-results.