The effects of Japanese encephalitis virus antibodies on Zika virus infection

Recently, Zika virus (ZIKV) has become more widespread, thus attracting global attention. The vaccine against Japanese encephalitis virus (JEV) is currently used in China, being included in planned immunisation regimes. Although ZIKV and JEV are closely related mosquito-borne Flaviviruses, and a complex cross-immune response within flaviviruses has been demonstrated, the effect of JEV vaccination on ZIKV infection has not been well described. Thus, this study aimed to explore the impact of different titres of anti-JEV antibodies (Abs) against ZIKV infection using sera from healthy human donors in Guangzhou and anti-JEV rabbit polyclonal antibodies (pAbs) in vitro and vivo. Human anti-JEV Ab titres were tested at decreasing concentrations as the age increased. A neutralising effect on ZIKV infection was observed when anti-JEV Ab titres in human sera or rabbit pAbs were high (the corresponding age was under 30 years). Even though a lower titre in human sera showed no apparent effect, whereas rabbit pAbs had an antibody-dependent enhancement(ADE)effect, we proved an ADE effect in vivo for the first time. This study suggests that individuals over 60 years of age are at high risk for JEV and ZIKV infection, and screening this age group for infection should strengthen. Furthermore, a deep exploration of the relationship between anti-JEV Abs and ZIKV infection is needed.

Cross-immunity in Nile tilapia vaccinated with Streptococcus agalactiae and Streptococcus iniae vaccines

Streptococcus agalactiae and Streptococcus iniae are major bacterial pathogens of tilapia that can cause high mortality concomitant with large economic losses to aquaculture. Although development of vaccines using formalin-killed bacteria to control these diseases has been attempted, the mechanism of immunity against streptococcal infections and the cross-protective ability of these two bacteria remains unclear. To explore the immunological role of these vaccines, we compared the immune responses of tilapia after immunization with both vaccines and compared the relative percent survival (RPS) and cross-immunization protection of tilapia after separate infection with S. agalactiae and S. iniae. All results revealed that vaccinated fish had significantly higher (P < 0.05) levels of specific antibodies than control fish 14 days post secondary vaccination (PSV) and 7 days post challenge. In vaccinated fish, the mRNA expression of interleukin-8 (IL-8), interleukin-12 (IL-12), caspase-3 (C-3), tumour necrosis factor (TNF), and interferon (IFN) was significantly up regulated (P < 0.05) in the head kidney after immunized; similar results were found for IL-8, TNF and IFN in the posterior kidney, meanwhile the expression levels of C-3 and IFN were significantly increased (P < 0.05) in the spleen of vaccinated fish. Additionally, the levels of acid phosphatase (ACP), alkaline phosphatase (AKP), superoxide dismutase (SOD), and lysozyme (LZM) in vaccinated fish were improved at different degree when compared to the control fish. These results showed that vaccination with formalin-killed cells (FKCs) of either S. agalactiae or S. iniae conferred protection against infection by the corresponding pathogen in Nile tilapia, resulting in RPS values of 92.3% and 91.7%, respectively. Furthermore, cross-protection was observed, as the S. agalactiae FKC vaccine protected fish from S. iniae infection, and vice versa. These results suggested that the S. agalactiae and S. iniae FKC vaccines can induce immune responses and generate excellent protective effects in Nile tilapia.

Fowl Adenovirus (FAdV) Recombination with Intertypic Crossovers in Genomes of FAdV-D and FAdV-E, Displaying Hybrid Serological Phenotypes

After analyzing 27 new genomes from fowl adenovirus (FAdV) field isolates and so-far unsequenced prototypes, we report the first evidence for recombination in FAdVs. Recombination was confined to species FAdV-D and FAdV-E, accommodating the largest number of, and the intraspecies-wise most differentiated, types. The majority of detected events occurred in FAdV-E, involving segments with parental origin of all constitutive types. Together with the diversity of breakpoints, this suggests widespread recombination in this species. With possible constraints through species-specific genes and diversification patterns, the recombinogenic potential of FAdVs attains particular interest for inclusion body hepatitis (IBH), an important disease in chickens, caused by types from the recombination-prone species. Autonomously evolving, recombinant segments were associated with major sites under positive selection, among them the capsid protein hexon and fiber genes, the right-terminal ORFs 19, 25, and the ORF20/20A family. The observed mosaicism in genes indicated as targets of adaptive pressures points toward an immune evasion strategy. Intertypic hexon/fiber-recombinants demonstrated hybrid neutralization profiles, retrospectively explaining reported controversies on reference strains B3-A, T8-A, and X11-A. Furthermore, cross-neutralization supported sequence-based evidence for interdomain recombination in fiber and contributed to a tentatively new type. Overall, our findings challenge the purported uniformity of types responsible for IBH, urging more complete identification strategies for FAdVs. Finally, important consequences arise for in vivo studies investigating cross-protection against IBH.

A Heat-Killed Cryptococcus Mutant Strain Induces Host Protection against Multiple Invasive Mycoses in a Murine Vaccine Model

Cryptococcus neoformans is a fungal pathogen that infects the lungs and then often disseminates to the central nervous system, causing meningitis. How Cryptococcus is able to suppress host immunity and escape the antifungal activity of macrophages remains incompletely understood. We reported that the F-box protein Fbp1, a subunit of the SCF(Fbp1) E3 ligase, promotes Cryptococcus virulence by regulating host-Cryptococcus interactions. Our recent studies demonstrated that the fbp1Δ mutant elicited superior protective Th1 host immunity in the lungs and that the enhanced immunogenicity of heat-killed fbp1Δ yeast cells can be harnessed to confer protection against a subsequent infection with the virulent parental strain. We therefore examined the use of heat-killed fbp1Δ cells in several vaccination strategies. Interestingly, the vaccine protection remains effective even in mice depleted of CD4+ T cells. This finding is particularly important in the context of HIV/AIDS-induced immune deficiency. Moreover, we observed that vaccinating mice with heat-killed fbp1Δ induces significant cross-protection against challenge with diverse invasive fungal pathogens, including C. neoformans, C. gattii, and Aspergillus fumigatus, as well as partial protection against Candida albicans Thus, our data suggest that the heat-killed fbp1Δ strain has the potential to be a suitable vaccine candidate against cryptococcosis and other invasive fungal infections in both immunocompetent and immunocompromised populations.IMPORTANCE Invasive fungal infections kill more than 1.5 million people each year, with limited treatment options. There is no vaccine available in clinical use to prevent and control fungal infections. Our recent studies showed that a mutant of the F-box protein Fbp1, a subunit of the SCF(Fbp1) E3 ligase in Cryptococcus neoformans, elicited superior protective Th1 host immunity. Here, we demonstrate that the heat-killed fbp1Δ cells (HK-fbp1) can be harnessed to confer protection against a challenge by the virulent parental strain, even in animals depleted of CD4+ T cells. This finding is particularly important in the context of HIV/AIDS-induced immune deficiency. Moreover, we observed that HK-fbp1 vaccination induces significant cross-protection against challenge with diverse invasive fungal pathogens. Thus, our data suggest that HK-fbp1 has the potential to be a broad-spectrum vaccine candidate against invasive fungal infections in both immunocompetent and immunocompromised populations.

Cross-Protection of Inactivated Rabies Vaccines for Veterinary Use against Bat Lyssaviruses Occurring in Europe

Human rabies vaccines have been shown to induce partial protection against members of phylogroup I bat lyssaviruses. Here, we investigated the capacity of a widely used rabies inactivated vaccine (Rabisin, Boehringer-Ingelheim) for veterinary use to cross-protect mice experimentally infected with European bat lyssavirus 1 (EBLV-1b), European bat lyssavirus 2 (EBLV-2), and Bokeloh bat lyssavirus (BBLV) occurring in Europe. For each lyssavirus, we investigated the efficacy of two different doses of vaccine against two viral doses administrated by either central or peripheral routes. In parallel, seroconversion following pre-exposure vaccination was investigated. In this study, we demonstrated that the three investigated bat isolates were pathogenic, even at low dose, when inoculated by the central route but were not/less pathogenic when administrated peripherally. The Rabisin vaccine was capable of significantly cross-protecting mice inoculated intramuscularly with EBLV-1b and EBLV-2 and intracerebrally with BBLV. The level of rabies neutralizing antibodies induced by the Rabisin was quite high against the bat lyssaviruses, but with no significant differences between immunization with 1 and 5 IU/dose. The study emphasizes that the quality of rabies-inactivated vaccines for veterinary use is of utmost importance to optimize the cross-protection of pets against phylogroup I bat lyssaviruses occurring in Europe.

A Recombinant Attenuated Yersinia pseudotuberculosis Vaccine Delivering a Y. pestis YopENt138-LcrV Fusion Elicits Broad Protection against Plague and Yersiniosis in Mice

In this study, a novel recombinant attenuated Yersinia pseudotuberculosis PB1+ strain (χ10069) engineered with ΔyopK ΔyopJ Δasd triple mutations was used to deliver a Y. pestis fusion protein, YopE amino acid 1 to 138-LcrV (YopENt138-LcrV), to Swiss Webster mice as a protective antigen against infections by yersiniae. χ10069 bacteria harboring the pYA5199 plasmid constitutively synthesized the YopENt138-LcrV fusion protein and secreted it via the type 3 secretion system (T3SS) at 37°C under calcium-deprived conditions. The attenuated strain χ10069(pYA5199) was manifested by the establishment of controlled infection in different tissues without developing conspicuous signs of disease in histopathological analysis of microtome sections. A single-dose oral immunization of χ10069(pYA5199) induced strong serum antibody titers (log10 mean value, 4.2), secretory IgA in bronchoalveolar lavage (BAL) fluid from immunized mice, and Yersinia-specific CD4+ and CD8+ T cells producing high levels of tumor necrosis factor alpha (TNF-α), gamma interferon (IFN-γ), and interleukin 2 (IL-2), as well as IL-17, in both lungs and spleens of immunized mice, conferring comprehensive Th1- and Th2-mediated immune responses and protection against bubonic and pneumonic plague challenges, with 80% and 90% survival, respectively. Mice immunized with χ10069(pYA5199) also exhibited complete protection against lethal oral infections by Yersinia enterocolitica WA and Y. pseudotuberculosis PB1+. These findings indicated that χ10069(pYA5199) as an oral vaccine induces protective immunity to prevent bubonic and pneumonic plague, as well as yersiniosis, in mice and would be a promising oral vaccine candidate for protection against plague and yersiniosis for human and veterinary applications.

Construction and characterization of a DNA vaccine encoding the SagH against Streptococcus iniae

Streptococcus iniae is an important aquaculture pathogen that is associated with disease outbreaks in wild and cultured fish species. Streptolysin S has been identified as an important virulence factor of S. iniae. With an aim to develop effective vaccines against S. iniae for Japanese flounder (Paralichthys olivaceus), in this study, we constructed a DNA vaccine based on the sagH gene, which belongs to the streptolysin S-associated gene cluster. In fish vaccinated with pSagH, the transcription of sagH was detected in tissues and SagH protein was also detected in the muscles of pSagH-vaccinated fish by immunohistochemistry. The immunoprotective effect of SagH showed that fish vaccinated with pSagH at one and two months exhibited a high relative percent survival (RPS) of 92.62% and 90.58% against S. iniae serotype I, respectively. In addition, SagH conferred strong cross protection against S. iniae serotype II and resulted in an RPS of 83.01% and 80.65% at one and two months, respectively. Compared to the control group, fish vaccinated with pSagH were able to induce much stronger respiratory burst activity, and higher titer of specific antibodies. The results of quantitative real-time PCR demonstrated that pSagH upregulated the expression of several immune genes that are possibly involved in both innate and adaptive immune responses. These results indicate that pSagH is a candidate DNA vaccine candidate against S. iniae serotype I and II infection in Japanese flounder in aquaculture.

Evaluation of Potato virus X mild mutants for cross protection against severe infection in China

BACKGROUND

Cross protection is a promising alternative to control plant viral diseases. One critical factor limiting the application of cross protection is the availability of attenuated mutants or mild strains. Potato virus X (PVX) infects many crops and induces huge economic losses to agricultural production. However, researches on the variability and mechanism of PVX virulence are scarce.

METHODS

The mutants were obtained by introducing mutations into the RNA dependent RNA polymerase (RdRp) gene of PVX via site-directed mutagenesis. Attenuated mutants were screen according to their symptoms in Nicotiana benthamiana plants. The protection efficacy against severe infection were evaluated with interval of 5, 10 and 15 days.

RESULTS

Among the 40 mutants obtained, four mutants carrying substitutions of either Glu46, Asn863, Asn968 or Glu1001 to Ala in PVX RdRp showed drastically attenuated symptom, accompanying with reduced accumulation levels of coat protein, plus- and minus-sense RNAs. When the interval between protective and challenging inoculations was 15 days, mutant E1001A (with substitution of Glu1001 to Ala in RdRp) provided complete protection against severe infection in both Nicotiana benthamiana and tomato, while E46A (Glu46 mutated to Ala) provided incomplete protection. To reduce the risk of reverse mutation, we constructed mutant dM which carries double mutations of both Glu46 and Glu1001 to Ala in RdRp. The mutant dM could provide effective protection against severe PVX infection.

CONCLUSION

Mutations of Glu46, Asn863, Asn968 or Glu1001 to Ala in PVX RdRp significantly reduced the viral symptoms. Mutants E1001A and E46A could provide effective protection against wild type PVX in both Nicotiana benthamiana and tomato. These results provide theoretical and practical bases for the control of PVX via cross protection.

Hemagglutinin Stalk-Reactive Antibodies Interfere with Influenza Virus Neuraminidase Activity by Steric Hindrance

Hemagglutinin (HA) stalk-reactive antibodies are the basis of several current "one-shot" universal influenza vaccine efforts because they protect against a wide spectrum of influenza virus strains. The appreciated mechanism of protection by HA stalk-reactive antibodies is to inhibit HA stalk reconfiguration, blocking viral fusion and entry. This study shows that HA stalk-reactive antibodies also inhibit neuraminidase (NA) enzymatic activity, prohibiting viral egress. NA inhibition (NI) was evident for an attached substrate but not for unattached small-molecule cleavage of sialic acid. This finding suggests that the antibodies inhibit NA enzymatic activity through steric hindrance, thus limiting NA access to sialic acids when adjacent to HA on whole virions. Consistently, F(ab')2 fragments that occupied reduced area without loss of avidity or disrupted HA/NA interactions showed significantly reduced NI activity. Notably, HA stalk-binding antibodies lacking NI activity were unable to neutralize viral infection via microneutralization assays. This work suggests that NI activity is an important component of protection mediated by HA stalk-reactive antibodies.IMPORTANCE This study reports a new mechanism of protection mediated by influenza hemagglutinin stalk-reactive antibodies, i.e., inhibition of neuraminidase activity by steric hindrance, blocking access of neuraminidase to sialic acids when it abuts hemagglutinin on whole virions.

The Multifaceted B Cell Response to Influenza Virus

Protection from yearly recurring, highly acute infections with a pathogen that rapidly and continuously evades previously induced protective neutralizing Abs, as seen during seasonal influenza virus infections, can be expected to require a B cell response that is too highly variable, able to adapt rapidly, and able to reduce morbidity and death when sterile immunity cannot be garnered quickly enough. As we outline in this Brief Review, the influenza-specific B cell response is exactly that: it is multifaceted, involves both innate-like and conventional B cells, provides early and later immune protection, employs B cells with distinct BCR repertoires and distinct modes of activation, and continuously adapts to the ever-changing virus while enhancing overall protection. A formidable response to a formidable pathogen.

Protection against homo and hetero-subtypic influenza A virus by optimized M2e DNA vaccine

Current influenza vaccines provide hemagglutinin strain-specific protection, but rarely provide cross-protection against divergent strains. It is, therefore, particularly important to develop a universal vaccine against conserved proteins or conserved regions of the virus. In this study, we used N-terminal extracellular region of the influenza virus M2 protein (M2e) as the target antigen and constructed two optimized M2e DNA vaccines (p-tPA-p3M2e and p-p3M2e) with increased antigenic epitope density and enhanced antigen secretion. Both vaccines induced high M2e-specific humoral and cellular immune responses in the vaccinated mice. These two vaccines also conferred protection against a lethal infection of homo-subtypic H1N1 virus, with p-tPA-p3M2e being the most effective. In addition, p-tPA-p3M2e also showed cross-protection against different subtypes of the influenza virus (H9N2, H6N6, and H10N8) at varying rates (80%, 40%, and 20%, respectively). After passive immunization, M2e DNA vaccine-induced antibodies in the sera provided complete protection against homologous virus challenge. An analysis of the mechanism underlying this immunization-mediated protection indicates that M2e-specific IgG and T-cell immune responses may play critical roles in the prevention of infection and viral clearance. Taken together, our results indicate that this optimized M2e DNA vaccine is a promising candidate for the development of a universal, broad-spectrum influenza virus vaccine.

Assessment of cross-protection to heterologous strains of Flavobacterium psychrophilum following vaccination with a live-attenuated coldwater disease immersion vaccine

Bacterial coldwater disease, caused by Flavobacterium psychrophilum, remains one of the most significant bacterial diseases of salmonids worldwide. A previously developed and reported live-attenuated immersion vaccine (F. psychrophilum; B.17-ILM) has been shown to confer significant protection to salmonids. To further characterize this vaccine, a series of experiments were carried out to determine the cross-protective efficacy of this B.17-ILM vaccine against 9 F. psychrophilum isolates (representing seven sequence types/three clonal complexes as determined by multilocus sequence typing) in comparison with a wild-type virulent strain, CSF-259-93. To assess protection, 28-day experimental challenges of rainbow trout (Oncorhynchus mykiss) fry were conducted following immersion vaccinations with the B.17-ILM vaccine. F. psychrophilum strains used in challenge trials were isolated from several fish species across the globe; however, all were found to be virulent in rainbow trout. The B.17-ILM vaccine provided significant protection against all strains, with relative percent survival values ranging from 51% to 72%. All vaccinated fish developed an adaptive immune response (as measured by F. psychrophilum-specific antibodies) that increased out to the time of challenge (8 weeks postimmunization). Previous studies have confirmed that antibody plays an important role in protection against F. psychrophilum challenge; therefore, specific antibodies to the B.17-ILM vaccine strain appear to contribute to the cross-protection observed to heterologous strain. The ability of such antibodies to bind to similar antigenic regions for all strains was confirmed by western blot analyses. Results presented here support the practical application of this live-attenuated vaccine, and suggest that it will be efficacious even in aquaculture operations affected by diverse strains of F. psychrophilum.

Nasal immunization with recombinant chimeric pneumococcal protein and cell wall from immunobiotic bacteria improve resistance of infant mice to Streptococcus pneumoniae infection

Respiratory tract infections and invasive disease caused by Streptococcus pneumoniae in high-risk groups are a major global health problem. Available human vaccines have reduced immunogenicity and low immunological memory in these populations, as well as high cost as a public health strategy in poor communities. In addition, no single pneumococcal protein antigen has been able to elicit protection comparable to that achieved using protein-polysaccharide conjugate vaccines. In this context, chimeric pneumococcal proteins raise as potential good vaccine candidates because of their simplicity of production and reduced cost. The aim of this work was to study whether the nasal immunization of infant mice with the recombinant chimeric pneumococcal protein (PSFP) was able to improve resistance to S. pneumoniae, and whether the immunomodulatory strain Lactobacillus rhamnosus CRL1505 or its cell wall (CW1505) could be used as effective mucosal adjuvants. Our results showed that the nasal immunization with PSPF improved pneumococcal-specific IgA and IgG levels in broncho-alveolar lavage (BAL), reduced lung bacterial counts, and avoided dissemination of pneumococci into the blood. Of interest, immunization with PSPF elicited cross-protective immunity against different pneumococcal serotypes. It was also observed that the nasal immunization of infant mice with PSPF+CW1505 significantly increased the production of pneumococcal-specific IgA and IgG in BAL, as well as IgM and IgG in serum when compared with PSPF alone. PSPF+CW1505 immunization also improved the reduction of pneumococcal lung colonization and its dissemination in to the bloodstream when compared to PSPF alone. Our results suggest that immunization with PSPF together with the cell wall of the immunomodulatory strain L. rhamnosus CRL1505 as a mucosal adjuvant could be an interesting alternative to improve protection against pneumococcal infection in children.

Determining the HPV vaccine schedule for a HIV-infected population in sub Saharan Africa, a commentary

BACKGROUND

Epidemiological studies have established human papillomavirus (HPV) infection as the central cause of invasive cervical cancer (ICC) and its precursor lesions. HIV is associated with a higher prevalence and persistence of a broader range of high-risk HPV genotypes, which in turn results in a higher risk of cervical disease. Recent WHO HPV vaccination schedule recommendations, along with the roll out of HAART at an earlier CD4 count within the female HIV-infected population, may have programmatic implications for sub Saharan Africa. This communication identifies research areas, which will need to be addressed for determining a HPV vaccine schedule for this population in sub Saharan Africa. A review of WHO latest recommendations and the evidence concerning one-dose HPV vaccine schedules was undertaken.

CONCLUSION

For females ≥15 years at the time of first dose and immunocompromised and/or HIV-infected, a 3-dose schedule (0, 1-2, 6 months) is recommended for all three vaccines. There is some evidence that there is similar protection against HPV 16 and 18 infection from a single vaccination than from two or three doses, however there is no cross protection conferred to other genotypes. There is a need for periodic prevalence studies to determine the vaccination coverage of bivalent, quadrivalent and nonavalent vaccine targeted oncogenic HPV genotypes in women with CIN 3 or ICC at national level. In light of the increasing number of sub Saharan HIV-infected girls initiating HAART at a CD4 count above 350 mm3, there are a number of clinical, virological and public health research gaps to address before a tailored vaccine schedule can be established for this population.

Broadly Reactive Human Monoclonal Antibodies Elicited following Pandemic H1N1 Influenza Virus Exposure Protect Mice against Highly Pathogenic H5N1 Challenge

Broadly cross-reactive antibodies (Abs) that recognize conserved epitopes within the influenza virus hemagglutinin (HA) stalk domain are of particular interest for their potential use as therapeutic and prophylactic agents against multiple influenza virus subtypes, including zoonotic virus strains. Here, we characterized four human HA stalk-reactive monoclonal antibodies (MAbs) for their binding breadth and affinity, in vitro neutralization capacity, and in vivo protective potential against an highly pathogenic avian influenza virus. The monoclonal antibodies were isolated from individuals shortly following infection with (70-1F02 and 1009-3B05) or vaccination against (05-2G02 and 09-3A01) A(H1N1)pdm09. Three of the MAbs bound HAs from multiple strains of group 1 viruses, and one MAb, 05-2G02, bound to both group 1 and group 2 influenza A virus HAs. All four antibodies prophylactically protected mice against a lethal challenge with the highly pathogenic A/Vietnam/1203/04 (H5N1) strain. Two MAbs, 70-1F02 and 09-3A01, were further tested for their therapeutic efficacy against the same strain and showed good efficacy in this setting as well. One MAb, 70-1F02, cocrystallized with H5 HA and showed heavy-chain-only interactions similar to those seen with the previously described CR6261 anti-stalk antibody. Finally, we show that antibodies that compete with these MAbs are prevalent in serum from an individual recently infected with the A(H1N1)pdm09 virus. The antibodies described here can be developed into broad-spectrum antiviral therapeutics that could be used to combat infections by zoonotic or emerging pandemic influenza viruses.IMPORTANCE The rise in zoonotic infections of humans by emerging influenza viruses is a worldwide public health concern. The majority of recent zoonotic human influenza cases were caused by H7N9 and H5Nx viruses and were associated with high morbidity and mortality. In addition, seasonal influenza viruses are estimated to cause up to 650,000 deaths annually worldwide. Currently available antiviral treatment options include only neuraminidase inhibitors, but some influenza viruses are naturally resistant to these drugs, and others quickly develop resistance-conferring mutations. Alternative therapeutics are urgently needed. Broadly protective antibodies that target the conserved "stalk" domain of the hemagglutinin represent potential potent antiviral prophylactic and therapeutic agents that can assist pandemic preparedness. Here, we describe four human monoclonal antibodies that target conserved regions of influenza HA and characterize their binding spectrum as well as their protective capacity in prophylactic and therapeutic settings against a lethal challenge with a zoonotic influenza virus.

Use of Proteins Identified through a Functional Genomic Screen To Develop a Protein Subunit Vaccine That Provides Significant Protection against Virulent Streptococcus suis in Pigs

Streptococcus suis is a bacterium that is commonly carried in the respiratory tract and that is also one of the most important invasive pathogens of swine, commonly causing meningitis, arthritis, and septicemia. Due to the existence of many serotypes and a wide range of immune evasion capabilities, efficacious vaccines are not readily available. The selection of S. suis protein candidates for inclusion in a vaccine was accomplished by identifying fitness genes through a functional genomics screen and selecting conserved predicted surface-associated proteins. Five candidate proteins were selected for evaluation in a vaccine trial and administered both intranasally and intramuscularly with one of two different adjuvant formulations. Clinical protection was evaluated by subsequent intranasal challenge with virulent S. suis While subunit vaccination with the S. suis proteins induced IgG antibodies to each individual protein and a cellular immune response to the pool of proteins and provided substantial protection from challenge with virulent S. suis, the immune response elicited and the degree of protection were dependent on the parenteral adjuvant given. Subunit vaccination induced IgG reactive against different S. suis serotypes, indicating a potential for cross protection.

Population-Level Effects of Human Papillomavirus Vaccination Programs on Infections with Nonvaccine Genotypes

We analyzed human papillomavirus (HPV) prevalences during prevaccination and postvaccination periods to consider possible changes in nonvaccine HPV genotypes after introduction of vaccines that confer protection against 2 high-risk types, HPV16 and HPV18. Our meta-analysis included 9 studies with data for 13,886 girls and women ≤19 years of age and 23,340 women 20-24 years of age. We found evidence of cross-protection for HPV31 among the younger age group after vaccine introduction but little evidence for reductions of HPV33 and HPV45. For the group this same age group, we also found slight increases in 2 nonvaccine high-risk HPV types (HPV39 and HPV52) and in 2 possible high-risk types (HPV53 and HPV73). However, results between age groups and vaccines used were inconsistent, and the increases had possible alternative explanations; consequently, these data provided no clear evidence for type replacement. Continued monitoring of these HPV genotypes is important.

Evidence for Viral Interference and Cross-reactive Protective Immunity Between Influenza B Virus Lineages

Background

Two influenza B virus lineages, B/Victoria and B/Yamagata, cocirculate in the human population. While the lineages are serologically distinct, cross-reactive responses to both lineages have been detected. Viral interference describes the situation whereby infection with one virus limits infection and replication of a second virus. We investigated the potential for viral interference between the influenza B virus lineages.

Methods

Ferrets were infected and then challenged 3, 10, or 28 days later with pairs of influenza B/Victoria and B/Yamagata viruses.

Results

Viral interference occurred at challenge intervals of 3 and 10 days and occasionally at 28 days. At the longer interval, shedding of challenge virus was reduced, and this correlated with cross-reactive interferon γ responses from lymph nodes from virus-infected animals. Viruses from both lineages could prevent or significantly limit subsequent infection with a virus from the other lineage. Coinfections were rare, indicating the potential for reassortment between lineages is limited.

Conclusions

These data suggest that innate and cross-reactive immunity mediate viral interference and that this may contribute to the dominance of a specific influenza B virus lineage in any given influenza season. Furthermore, infection with one influenza B virus lineage may be beneficial in protecting against subsequent infection with either influenza B virus lineage.

Comparison of the Impact of Pneumococcal Conjugate Vaccine 10 or Pneumococcal Conjugate Vaccine 13 on Invasive Pneumococcal Disease in Equivalent Populations

Background

Pneumococcal conjugate vaccine 10 (PCV10) and pneumococcal conjugate vaccine 13 (PCV13), are used in childhood immunization programs worldwide, but direct comparisons of impacts against invasive pneumococcal disease (IPD) in equivalent populations have not been performed. We compared the vaccines (prevaccination 2007-2009 vs postvaccination 2013-2016) in Sweden, where the 21 counties use either PCV10 or PCV13 (introduced 2009-2010).

Methods

All IPD episodes (n = 16992) were recorded in Sweden during 2005-2016. Of 14 186 isolates from 2007-2016, 13 468 (94.9%) were characterized with serotyping and 12 235 (86.2%) with antibiotic susceptibility. Poisson models assessed changes in incidence over time.

Results

Invasive pneumococcal disease incidences decreased between 2005 and 2016 in vaccinated children (by 68.5%), and in the whole population (by 13.5%), but not among the elderly (increased by 2%) due to a substantial increase in nonvaccine types (NVTs). In 2016, NVTs constituted 72% of IPD cases in the elderly. Serotype 6A declined in PCV10 and PCV13 counties, whereas serotype 19A increased in PCV10 counties. There was no effect against serotype 3. Cross-protection was found between 6B and 6A but not between 19F and 19A. Serotype 6C increased in PCV10 counties, but not in PCV13 counties, suggesting cross-protection with 6A, which is included in PCV13. In the elderly, the increase in NVTs, excluding 6C, was more pronounced in PCV13 counties.

Conclusions

The overall impact of IPD incidences was not statistically different irrespective of vaccine used. The incidence of serotypes, where the effect of the vaccines differed, will influence the cost-effectiveness of which vaccine to use in immunization programs. The dominance of NVTs suggests a limited effect of current pediatric PCVs against IPD in the elderly.

Intranasal co-administration of 1,8-cineole with influenza vaccine provide cross-protection against influenza virus infection

BACKGROUND

Vaccination is the most efficient means for protection against influenza. However, the various vaccines have low efficacy to protect against pandemic strains because of antigenic drift and recombination of influenza virus. Adjuvant therapy is one of the attempts to improve influenza vaccine effective cross-protection against influenza virus infection. Our previous study confirmed that 1,8-cineole inhibits the NF-κB, reduces pro-inflammatory cytokines, and relieves the pathological changes of viral pneumonia in mice infected with influenza virus.

HYPOTHESIS/PURPOSE

1,8-cineole, administered via intranasal (i.n.) route, may also have the capacity to be an adjuvant of the influenza vaccine. This study was designed to investigate the potential use of i.n. co-administration of 1,8-cineole, a major component of the Eucalyptus essential oils, with influenza vaccine and whether could provide cross-protection against influenza virus infection in a mouse model.

STUDY DESIGN

I.n. co-administration of 1,8-cineole in two doses (6.25 and 12.5 mg/kg) with influenza vaccine was investigated in a mouse model in order to see whether it could provide cross-protection against influenza virus infection.

METHODS

The mice were intranasally immunized three times at the 0, 7 and 14 day with vaccine containing 0.2 µg hemagglutinin (HA) and/or without 1,8-cineole. Seven days after the 3rd immunization dose, the mice were infected with 50 µl of 15 LD₅₀ (50% mouse lethal dose) influenza virus A/FM/1/47 (H1N1). On day 6 post-infection, 10 mice per group were sacrificed to collect samples, to take the body weight and lung, and detect the viral load, pathological changes in the lungs and antibody, etc. The collected samples included blood serum and nasal lavage fluids. In addition, the survival experiments were carried out  to investigate the survival of mice.

RESULTS

Mice i.n. inoculated with influenza vaccine and 12.5 mg/kg 1,8-cineole increased the production of influenza-specific serum immunoglobulin (Ig) G2a antibodies, stimulated mucosal secretive IgA (s-IgA) responses at the nasal cavity, improved the expression of respiratory tract intraepithelial lymphocytes (IELs) in the upper respiratory tract, and promoted dendritic cell (DC) maturation and the expression of co-stimulatory molecules cluster of differentiation (CD)40, CD80 and CD86 in peripheral blood. Importantly, mice that had received 1,8-cineole-supplemented influenza vaccine showed longer survival time, milder inflammation, less weight loss and mortality rate and lower lung index and viral titers compared to that of mice immunized a non-1,8-cineole-adjuvanted split vaccine. Thus, i.n. immunization with 1,8-cineole-adjuvanted vaccine induces a superior cross-protective immunity against infection with influenza than an inactivated vaccine only.

CONCLUSION

These results suggest that 1,8-cineole (12.5 mg/kg) has a cross-protection against influenza virus, co-administered with inactivated influenza viral antigen in a mouse model.

Adenovirus vector-based multi-epitope vaccine provides partial protection against H5, H7, and H9 avian influenza viruses

The emergence of H5, H7, and H9 avian influenza virus subtypes in humans reveals their pandemic potential. Although human-to-human transmission has been limited, the genetic reassortment of the avian and human/porcine influenza viruses or mutations in some of the genes resulting in virus replication in the upper respiratory tract of humans could generate novel pandemic influenza viruses. Current vaccines do not provide cross protection against antigenically distinct strains of the H5, H7, and H9 influenza viruses. Therefore, newer vaccine approaches are needed to overcome these potential threats. We developed an egg-independent, adenovirus vector-based, multi-epitope (ME) vaccine approach using the relatively conserved immunogenic domains of the H5N1 influenza virus [M2 ectodomain (M2e), hemagglutinin (HA) fusion domain (HFD), T-cell epitope of nucleoprotein (TNP). and HA α-helix domain (HαD)]. Our ME vaccine induced humoral and cell-mediated immune responses and caused a significant reduction in the viral loads in the lungs of vaccinated mice that were challenged with antigenically distinct H5, H7, or H9 avian influenza viruses. These results suggest that our ME vaccine approach provided broad protection against the avian influenza viruses. Further improvement of this vaccine will lead to a pre-pandemic vaccine that may lower morbidity, hinder transmission, and prevent mortality in a pandemic situation before a strain-matched vaccine becomes available.

Immune efficacy of an adenoviral vector-based swine influenza vaccine against antigenically distinct H1N1 strains in mice

Avian-like H1N1 swine influenza viruses are prevalent in pigs and have occasionally crossed the species barrier and infected humans, which highlights the importance of preventing swine influenza. Human adenovirus serotype 5 (Ad5) has been tested in human influenza vaccine clinical trials and has exhibited a reliable safety profile. Here, we generated a replication-defective, recombinant adenovirus (designated as rAd5-avH1HA) expressing the hemagglutinin gene of an avian-like H1N1 virus (A/swine/Zhejiang/199/2013, ZJ/199/13). Using a BALB/c mouse model, we showed that a two-dose intramuscular administration of recombinant rAd5-avH1HA induced high levels of hemagglutination inhibition antibodies and prevented homologous and heterologous H1N1 virus-induced weight loss, as well as viral replication in the nasal turbinates and lungs of mice. Furthermore, a prime-boost immunization strategy trial with a recombinant plasmid (designated as pCAGGS-HA) followed by rAd5-avH1HA vaccine provided effective protection against homologous and heterologous H1N1 virus infection in mice. These results indicate that rAd5-avH1HA is an efficacious genetically engineered vaccine candidate against H1N1 swine influenza. Future studies should examine its immune efficacy in pigs.

Recombinant influenza H7 hemagglutinin containing CFLLC minidomain in the transmembrane domain showed enhanced cross-protection in mice

Since February 2013, H7N9 influenza virus, causing human infections with high mortality in China, has been a potential pandemic threat. The H7N9 viruses are found to diverge into distinct genotypes as other influenza viruses; thus a vaccine that can provide sufficient cross-protection against different genotypes of H7N9 viruses is urgently needed. Our previous studies demonstrated that the HA-based structural design approach by introducing a CFLLC minidomain into transmembrane domain (TM) of H1, H5 or H9 hemagglutinin (HA) proteins by replacing with H3 subtype HA TM could enhance their cross-protection. In this study, we used Sf9 insect cell expression system to express recombinant H7 HA proteins H7-53WT, in which HA gene was derived from H7N9-53 strain, and H7-53TM containing CFLLC minidomian by replacing its TM domain with H3 HA TM. We investigated whether introduction of CFLLC minidomain into H7 HA (H7-53TM) could increase its cross-reactivity and cross-protection against different genotypes of H7N9 viruses. The results showed that the H7-53TM either with or without squalene adjuvant induced increased HI antibodies, serum IgG antibodies, and IFN-γ production to a panel of 7 H7N9 viruses in mice. Vaccinated animals with H7-53TM alone showed complete protection against challenge with heterologous H7N9-MCX strain, while H7-53WT alone showed incomplete protection (80%). Furthermore, mice vaccinated with H7-53TM HA showed less body weight loss and less pulmonary lesions and inflammation after challenge with homologous or heterologous H7N9 viruses, comparing to H7-53WT. In summary, this study presents a better subunit vaccine candidate (H7-53TM) against potential H7N9 pandemic.

Generation of a Live Attenuated Influenza Vaccine that Elicits Broad Protection in Mice and Ferrets

New influenza vaccines that provide effective and broad protection are desperately needed. Live attenuated viruses are attractive vaccine candidates because they can elicit both humoral and cellular immune responses. However, recent formulations of live attenuated influenza vaccines (LAIVs) have not been protective. We combined high-coverage transposon mutagenesis of influenza virus with a rapid high-throughput screening for attenuation to generate W7-791, a live attenuated mutant virus strain. W7-791 produced only a transient asymptomatic infection in adult and neonatal mice even at doses 100-fold higher than the LD₅₀ of the parent strain. A single administration of W7-791 conferred full protection to mice against lethal challenge with H1N1, H3N2, and H5N1 strains, and improved viral clearance in ferrets. Adoptive transfer of T cells from W7-791-immunized mice conferred heterologous protection, indicating a role for T cell-mediated immunity. These studies present an LAIV development strategy to rapidly generate and screen entire libraries of viral clones.

An Adenovirus-Vectored Influenza Vaccine Induces Durable Cross-Protective Hemagglutinin Stalk Antibody Responses in Mice

Currently licensed vaccines against the influenza A virus (IAV) need to be updated annually to match the constantly evolving antigenicity of the influenza virus glycoproteins, hemagglutinin (HA), and neuramidiase (NA). Attempts to develop universal vaccines that provide broad protection have resulted in some success. Herein, we have shown that a replication-deficient adenovirus expressing H5/M2e induced significant humoral immunity against the conserved HA stalk. Compared to the humoral responses induced by an inactivated influenza vaccine, the humoral responses induced by the adenovirus-vectored vaccine against the conserved stalk domain mediated cross-protection against heterosubtypic influenza viruses. Importantly, virus inactivation by formaldehyde significantly reduced the binding of monoclonal antibodies (mAbs) to the conserved nucleoprotein (NP), M2e, and HA stalk. These results suggest that inactivation by formaldehyde significantly alters the antigenicity of the HA stalk, and suggest that the conformation of the intact HA stalk provided by vector-based vaccines is important for induction of HA stalk-binding Abs. Our study provides insight into the mechanism by which a vector-based vaccine induces broad protection by stimulation of cross-protective Abs targeting conserved domains of viral proteins. The findings support further strategies to develop a vectored vaccine as a universal influenza vaccine for the control of influenza epidemics and unpredicted pandemics.