The endemic GII.4 norovirus-like-particle induced-antibody lacks of cross-reactivity against the epidemic GII.17 strain

Norovirus-like particle (VLP) vaccine is promising against human norovirus infection. Unfortunately, genetic diversity of norovirus hindered the development of this vaccine. In this study, the immunogenicity of norovirus VLPs induced by the endemic GII.4 and the epidemic GII.17 genotypes, and the cross-reactivity between them as well as GI.1 and GII.3 VLPs were evaluated in mice by using serum IgG and histo-blood group antigen (HBGA) blocking antibodies as index. Results showed well immunogenicity of both GII.4 and GII.17 VLPs in mice. Serum IgG GMT (Geometric Mean Titer) were 3.63 (GII.4) and 3.88 (GII.17) respectively, and sustained to the 15th week. The HBGA blocking antibodies were 130 (GII.4) and 360 (GII.17) respectively at the end of the 4th week. Additionally, there was a dramatically statistical difference found in the cross-reactivity within genogroup (GII.3, GII.4 and GII.17) (p < .001), and also showed similar difference between genogroups (GI.1 vs. GII.3, GII.4 and GII.17) (p < .001). Summarized the pPICZa pichi pichia expression system showed a potential to be the alternative for expression of norovirus VLPs in secretion form, and the little cross-reactivity found between the endemic strain and the epidemic strain provides an evident for the consideration of selecting candidates of norovirus vaccine strains.

Flow virometry for process monitoring of live virus vaccines-lessons learned from ERVEBO

Direct at line monitoring of live virus particles in commercial manufacturing of vaccines is challenging due to their small size. Detection of malformed or damaged virions with reduced potency is rate-limited by release potency assays with long turnaround times. Thus, preempting batch failures caused by out of specification potency results is almost impossible. Much needed are in-process tools that can monitor and detect compromised viral particles in live-virus vaccines (LVVs) manufacturing based on changes in their biophysical properties to provide timely measures to rectify process stresses leading to such damage. Using ERVEBO, MSD's Ebola virus vaccine as an example, here we describe a flow virometry assay that can quickly detect damaged virus particles and provide mechanistic insight into process parameters contributing to the damage. Furthermore, we describe a 24-h high throughput infectivity assay that can be used to correlate damaged particles directly to loss in viral infectivity (potency) in-process. Collectively, we provide a set of innovative tools to enable rapid process development, process monitoring, and control strategy implementation in large scale LVV manufacturing.

Whither COVID-19 vaccines?

Nature Biotechnology convenes a group of experts to provide their insights into SARS-CoV-2 vaccines in development.

The Brighton Collaboration standardized template for collection of key information for benefit-risk assessment of inactivated viral vaccines

Inactivated viral vaccines have long been used in humans for diseases of global health threat and are now among the vaccines for COVID-19 under development. The Brighton Collaboration Viral Vector Vaccines Safety Working Group (V3SWG) has prepared a standardized template to describe the key considerations for the benefit-risk assessment of inactivated viral vaccines. This will help key stakeholders to assess potential safety issues and understand the benefit-risk of the vaccine platform. The standardized and structured assessment provided by the template would also help to contribute to improved communication and support public acceptance of licensed inactivated viral vaccines.

The Challenges of Vaccine Development against a New Virus during a Pandemic

The rapid emergence of a highly pathogenic, readily transmissible coronavirus has resulted in a global pandemic, affecting millions and destabilizing economies. This catastrophe triggered a clarion call for the immediate deployment of a protective vaccine. We describe the unique challenges of developing a vaccine against SARS-CoV-2 in a pandemic setting.

Human Challenge Studies to Accelerate Coronavirus Vaccine Licensure

Controlled human challenge trials of SARS-CoV-2 vaccine candidates could accelerate the testing and potential rollout of efficacious vaccines. By replacing conventional phase 3 testing of vaccine candidates, such trials may subtract many months from the licensure process, making efficacious vaccines available more quickly. Obviously, challenging volunteers with this live virus risks inducing severe disease and possibly even death. However, we argue that such studies, by accelerating vaccine evaluation, could reduce the global burden of coronavirus-related mortality and morbidity. Volunteers in such studies could autonomously authorize the risks to themselves, and their net risk could be acceptable if participants comprise healthy young adults, who are at relatively low risk of serious disease following natural infection, if they have a high baseline risk of natural infection, and if during the trial they receive frequent monitoring and, following any infection, the best available care.

Establishing China's national standards of antigen content and neutralizing antibody responses for evaluation of SFTS vaccines

Severe fever with thrombocytopenia syndrome (SFTS) is an acute infectious disease caused by severe fever with thrombocytopenia syndrome virus (SFTSV). SFTS is mainly characterized by severe fever with thrombocytopenia and has a high mortality rate. The virus has been found in China, South Korea, and Japan. Effective antiviral drugs or vaccines still have been unavailable. Now, two vaccine manufacturers in China are actively engaged in the development of the vaccine. To promote the development of SFTS vaccines and ensure their effective quality control, we developed national antigen and antibody references. We collaborative calibrated the standards; evaluated the homogeneity and stability of the national SFTS standards. The national SFTS vaccine antigen and antibody references met the Chinese national standards and can be used to standardize quality control for the manufacture of SFTS vaccines. And also can be used into the study the dose-response relationship of SFTS vaccines, determine clinical doses, and evaluate vaccine immunogenicity.

Chicken anemia virus: A deadly pathogen of poultry

Chicken infectious anemia (CIA) is an immunosuppressive disease that causes great economic loss in poultry industry globally. This disease is caused by chicken anemia virus (CAV), an icosahedral and single-stranded DNA virus that is transmitted both vertically and horizontally. CAV, which belongs to the genus Gyrovirus has been reported in human, mouse and dog feces. Rapid identification of different strains of gyrovirus with high similarity to CAV has heightened public concern on this virus. Clinical symptoms of this disease such as intramuscular hemorrhage, weight loss, anemia and bone marrow aplasia are prominent in young chickens, while adult chickens experience subclinical symptoms. Biosecurity measures such as good management practice and vaccination have been the most reliable control strategy against this virus. Therefore, this study reviews the current state of CAV under the following subheadings (i) Chicken anemia virus (ii) Pathogenesis of CAV (iii) Serological evaluation of host antibodies to CAV (iv) Association of Marek's disease and infectious bursa disease with CAV infection (v) Genetic diversity and phylogenetics of CAV strains (vi) Current and future vaccine strategy in the control of CAV. In conclusion, improvement on DNA and recombinant vaccines strategy could curtail the economic impact of CAV on poultry birds. Keywords: adjuvant; CAV; chicken; disease.

Severe fever and thrombocytopenia syndrome virus infection: Considerations for vaccine evaluation of a rare disease

Infection caused by the severe fever and thrombocytopenia syndrome virus (SFTSV) causes a hemorrhagic illness with a mortality between 20% and 40%. Initially recognized in 2009 in China, cases have additionally been documented in Japan and Korea although retrospective studies have documented seroprevalence since 1996. Although case rates have increased due to increased awareness and more widely available diagnostics, SFTSV infection remains rare with the highest rates documented in Korea for Jeju Province (3.5 cases per 100,000 population) and the Inje-gun region (66.2 cases per 100,000). Because of the very low incidence of infection, a placebo-controlled study with 1:1 randomization to evaluate an SFTSV vaccine would require a sample size that is 25% greater than the region of study. We discuss alternatives to licensure. Vaccine effectiveness may be assessed through a registry, comparing rates of infection over time between vaccine recipients versus regional populations. Modeled data can be updated based on actual case rates and population changes over the years of follow-up. Using one model, statistically significant differences are seen after 10 years in Inje-gun and 15 years of follow-up in Jeju. This approach may be applicable to other uncommon infectious diseases for which a standard study design is difficult.

A simple and rapid assay to evaluate purity of foot-and-mouth disease vaccine before animal experimentation

Currently, foot-and-mouth disease (FMD) vaccine purity is tested in cattle to detect antibodies against the non-structural protein (NSP) after repeated immunization with the final vaccine product. In case of vaccine failure, the manufacturing company would suffer significant economic loss. To prevent such unfortunate losses with the final vaccine product, in vitro testing is required to quantitate an NSP antigen during the manufacturing process prior to animal experiments. A novel lateral-flow assay device was developed using a monoclonal antibody (MAb) against the 3B NSP. To determine the minimal amount of NSP required to elicit antibodies in livestock, goats were immunized several times with various concentrations of either the recombinant 3AB (rec.3AB) protein or FMD virus culture supernatant. Antibodies against 3AB were elicited after a second immunization with 10.6 ng to 42.5 ng of rec.3AB and a third immunization with a 10-fold diluted FMD virus culture supernatant in goats. The lateral-flow assay device detected the minimal amount of rec.3AB and native NSP in FMD virus culture supernatant required to induce NSP antibodies in goats. The in vitro assay device is simple and economical, provides rapid results, and should be useful for FMD vaccine-manufacturing companies prior to conducting animal experiments to test the vaccine purity.

Immunogenicity and safety of three consecutive production lots of the non replicating smallpox vaccine MVA: A randomised, double blind, placebo controlled phase III trial

Background

Modified Vaccinia Ankara (MVA) is a live, viral vaccine under advanced development as a non-replicating smallpox vaccine. A randomised, double-blind, placebo-controlled phase III clinical trial was conducted to demonstrate the humoral immunogenic equivalence of three consecutively manufactured MVA production lots, and to confirm the safety and tolerability of MVA focusing on cardiac readouts.

Methods

The trial was conducted at 34 sites in the US. Vaccinia-naïve adults aged 18-40 years were randomly allocated to one of four groups using a 1:1:1:1 randomization scheme. Subjects received either two MVA injections from three consecutive lots (Groups 1-3), or two placebo injections (Group 4), four weeks apart. Everyone except personnel involved in vaccine handling and administration was blinded to treatment. Safety assessment focused on cardiac monitoring throughout the trial. Vaccinia-specific antibody titers were measured using a Plaque Reduction Neutralization Test (PRNT) and an Enzyme-Linked Immunosorbent Assay (ELISA). The primary immunogenicity endpoint was Geometric Mean Titers (GMTs) after two MVA vaccinations measured by PRNT at trial visit 4. This trial is registered with ClinicalTrials.gov, number NCT01144637.

Results

Between March 2013 and May 2014, 4005 subjects were enrolled and received at least one injection of MVA (n = 3003) or placebo (n = 1002). The three MVA lots induced equivalent antibody titers two weeks after the second vaccination, with seroconversion rates of 99·8% (PRNT) and 99·7% (ELISA). Overall, 180 (6·0%) subjects receiving MVA and 29 (2·9%) subjects in the placebo group reported at least one unsolicited Adverse Event (AE) that was considered trial-related. Vaccination was well tolerated without significant safety concerns, particularly regarding cardiac assessment.

Conclusions

The neutralizing and total antibody titers induced by each of the three lots were equivalent. No significant safety concerns emerged in this healthy trial population, especially regarding cardiac safety, thus confirming the excellent safety and tolerability profile of MVA.

Trial registration

ClinicalTrials.gov NCT01144637

Efficacy of intranasal vaccination with a multivalent vaccine containing temperature-sensitive modified-live bovine herpesvirus type 1 for protection of seronegative and seropositive calves against respiratory disease

OBJECTIVE To evaluate efficacy and duration of immunity of the bovine herpesvirus type 1 (BHV-1) fraction of a trivalent vaccine also containing parainfluenza virus-3 and bovine respiratory syncytial virus fractions administered intranasally (IN) for protection of calves against infectious bovine rhinotracheitis (IBR). DESIGN Controlled challenge study. ANIMALS 120 dairy calves (3 to 8 days old) seronegative for antibody against BHV-1 (experiments 1 and 2) or seropositive for maternally derived antibody against BHV-1 (experiment 3). PROCEDURES In 3 separate experiments, calves were vaccinated IN via 2 nostrils (experiment 1) or 1 nostril (experiments 2 and 3) with a vaccine containing or not containing a BHV-1 fraction. For seronegative calves, the test vaccine contained a minimum immunizing dose of BHV-1; for seropositive calves, it contained a commercial dose of BHV-1. Calves were challenged IN with virulent BHV-1 on day 28 or 193 (seronegative calves) or day 105 (seropositive calves) after vaccination to evaluate vaccine efficacy. Frequency and duration of clinical signs, rectal temperatures, virus shedding, and serologic responses were compared between treatment groups within experiments. RESULTS In all experiments, BHV-1 vaccinated calves had lower frequencies or shorter durations of clinical signs of IBR than did control calves. Following viral challenge, peak rectal temperatures and degrees of virus shedding were lower and serologic responses were higher in vaccinated versus control calves. CONCLUSIONS AND CLINICAL RELEVANCE IN vaccination against BHV-1 protected all calves against clinical IBR disease, regardless of serologic status at the time of vaccination, and suppressed virus shedding. A single dose of this IN vaccine has the potential to protect seronegative calves for at least 193 days and override maternally derived antibody to protect seropositive calves for at least 105 days.

Ebola vaccine development plan: ethics, concerns and proposed measures

BACKGROUND

The global interest in developing therapies for Ebola infection management and its prevention is laudable. However the plan to conduct an emergency immunization program specifically for healthcare workers using experimental vaccines raises some ethical concerns. This paper shares perspectives on these concerns and suggests how some of them may best be addressed.

DISCUSSION

The recruitment of healthcare workers for Ebola vaccine research has challenges. It could result in coercion of initially dissenting healthcare workers to assist in the management of EVD infected persons due to mistaken beliefs that the vaccine offers protection. It could also affect equity and justice. For example, where people who are not skilled health care professionals but who provide care to patients infected with Ebola (such as in home care settings) are not prioritized for vaccination. The possibility of study participants contracting Ebola infection despite the use of experimental vaccine, and the standard of care they would receive, needs to be addressed clearly, transparently and formalized as part of the ethics review process. Future access to study products in view of current status of the TRIPS agreement needs to be addressed. Finally, broad stakeholder engagement at local, regional and international levels needs to be promoted using available communication channels to engage local, regional and international support. These same concerns are applicable for current and future epidemics. Successful Ebola vaccine development research requires concerted efforts at public dialogue to address misconceptions, equity and justice in participant selection, and honest discussions about risks, benefits and future access. Public dialogue about Ebola vaccine research plans is crucial and should be conducted by trusted locals and negotiated between communities, researchers and ethics committees in research study sites.

An attenuated virus vaccine appears safe to the central nervous system of rainbow trout (Oncorhynchus mykiss) after intranasal delivery

Nasal vaccines are very effective but the olfactory organ provides direct access of antigens to the brain. Infectious hematopoietic necrosis virus (IHNV) is known to cause high mortalities in salmonids. The purpose of this study is to evaluate the safety of a live attenuated IHNV nasal (I.N) vaccine in rainbow trout (Oncorhynchus mykiss). In the olfactory organ, the vaccine was detected 1 and 4 days after primary I.N vaccination but not in the intramuscular (i.m) or control groups. In the brain, IHNV was detected by RT-qPCR 4 and 21 days after i.m primary vaccination. One i.m and one I.N vaccinated trout were positive at days 4 and 28 days post-boost, respectively. Presence of IHNV in the brain of i.m vaccinated fish correlated with moderate increases in IL-1β and TNF-α expression in this tissue. These results demonstrate that IHNV vaccine lasts for 4 days in the local nasal environment and that nasal vaccination appears to be safe to the CNS of rainbow trout.

Importance of foot and mouth disease vaccine purity in interpreting serological surveys

The aim of this study was to determine whether the degree of purity achieved in conventional vaccines against the foot and mouth disease virus in Argentina interferes with the interpretation of seroepidemiological surveys for confirming the absence of viral activity, which are performed to support the recognition of free zones practising vaccination. The evaluation of 168 vaccine series due to be marketed in Argentina (2006-2012) and subjected to official control testing in cattle, as well as repeated vaccination of cattle and other species using vaccines with high antigen concentrations, demonstrated that they did not induce antibodies to non-structural proteins (NSPs). The results show clearly that vaccines with satisfactory potency do not induce a response to NSPs, even by forcing the immune response through more concentrated doses with multiple valences and revaccination protocols at shorter irtervals than in vaccination campaigns. These results confirm that the vaccines used in routine vaccination programmes have a degree of antigen purification consistent with the needs observed on the basis of sampling for serological surveillance. Moreover, serological surveys conducted in 2006-2011 by Argentina's official Veterinary Services--the National Health and Agrifood Quality Service (SENASA)--on more than 23,000 sera per year from cattle included in the vaccination programme, in order to confirm the absence of virus circulation, revealed an average 0.05% of reactive results, consistent with the specificity of the tests. In conclusion, the vaccines produced by conventional methods and with proven potencythat are available in Argentina are sufficiently purified to ensure thatthey do not interfere with the interpretation of sampling for serological surveillance performed to support the recognition of FMD-free zones practising vaccination.

A Multicenter, Open-Label, Controlled Phase II Study to Evaluate Safety and Immunogenicity of MVA Smallpox Vaccine (IMVAMUNE) in 18-40 Year Old Subjects with Diagnosed Atopic Dermatitis

Background

Replicating smallpox vaccines can cause severe complications in individuals with atopic dermatitis (AD). Prior studies evaluating Modified Vaccinia Ankara virus (MVA), a non-replicating vaccine in humans, showed a favorable safety and immunogenicity profile in healthy volunteers.

Objective

This Phase II study compared the safety and immunogenicity of MVA enrolling groups of 350 subjects with AD (SCORAD ≤ 30) and 282 healthy subjects.

Methods

Subjects were vaccinated twice with MVA, each dose given subcutaneously 4 weeks apart. Adverse events, cardiac parameters, and the development of vaccinia virus humoral immune responses were monitored.

Results

The overall safety of the vaccine was similar in both groups. Adverse events affecting skin were experienced significantly more often in subjects with AD, but the majority of these events were mild to moderate in intensity. Seroconversion rates and geometric mean titers for total and neutralizing vaccinia-specific antibodies in the AD group were non-inferior compared to the healthy subjects.

Limitations

The size of the study population limited the detection of serious adverse events occurring at a frequency less than 1%.

Conclusion

MVA has a favorable safety profile and the ability to elicit vaccinia-specific immune responses in subjects with AD.

Trial Registration

ClinicalTrials.gov NCT00316602

A novel vaccine against Porcine circovirus type 2 (PCV2) and Streptococcus equi ssp. zooepidemicus (SEZ) co-infection

To develop a vaccine against Porcine circovirus type 2 (PCV2) and Streptococcus equi ssp. zooepidemicus (SEZ) co-infection, the genes of porcine IL-18, capsid protein (Cap) of PCV2 and M-like protein (SzP) of SEZ were inserted into the swinepox virus (SPV) genome by homologous recombination. The recombinant swinepox virus rSPV-ICS was verified by PCR and indirect immunofluorescence assays. To evaluate the immunogenicity of rSPV-ICS, 28 PCV2 and SEZ seronegative Bama minipigs were immunized with rSPV-ICS (n=8), commercial PCV2 vaccine and SEZ vaccine (n=8) or wild type SPV (n=8). The results showed that SzP-specific antibody and PCV2 neutralizing antibody of the rSPV-ICS immunized group increased significantly compared to the wild type SPV treated group after vaccination and increased continuously over time. The levels of IL-4 and IFN-γ in the rSPV-ICS immunized group were significantly higher than the other three groups, respectively. After been co-challenged with PCV2 and SEZ, 87.5% piglets in rSPV-ICS immunized group were survived. Significant reductions in gross lung lesion score, histopathological lung lesion score, and lymph node lesion score were noticed in the rSPV-ICS immunized group compared with the wtSPV treated group. The results suggested that the recombinant rSPV-ICS provided piglets with significant protection against PCV2-SEZ co-infection; thus, it offers proof-of-principle for the development of a vaccine for the prevention of these swine diseases.

Porcine circovirus type 2 decreases the infection and replication of attenuated classical swine fever virus in porcine alveolar macrophages

Recently, it has been noted that porcine circovirus type 2 (PCV2) infection adversely affects the protective efficacy of Lapinized Philippines Coronel (LPC) vaccine, an attenuated strain of classical swine fever virus (CSFV), in pigs. In order to investigate the possible mechanisms of the PCV2-derived interference, an in vitro model was established to study the interaction of LPC virus (LPCV) and PCV2 in porcine alveolar macrophages (AMs). The results showed that PCV2 reduced the LPCV infection in AMs and the levels of PCV2-derived interference were dose-dependent. The PCV2-derived interference also reduced the replication level of LPCV in AMs. The full-length PCV2 DNA and its fragment DNA C9 CpG-ODN were involved in the reduction of LPCV infection in AMs, whereas UV-inactivated PCV2 was not. In addition, a moderate negative correlation between the LPCV antigen-containing rate and IFN-γ production was observed, and had a dose-dependent trend with the level of PCV2-inoculation. The results of the present study may partially explain how PCV2 infection interferes with the efficacy of LPC vaccine.

Production of viral vaccines for veterinary use

This review provides inside information on the production of vaccines for veterinary use. The vaccines against rinderpest as well as foot and mouth disease are considered milestones in the history of veterinary vaccine production. Modern vaccines are based on the scientific progress in virology, cell biology and immunology. While naturally occurring attenuated viruses or viruses obtained after passage in different animal species or cell culture were used as vaccine strains in the early vaccines, nowadays targeted mutagenesis can be applied to generate vaccine virus strains. In principle, the antigen production process is the same for live and inactivated vaccines. The vaccine virus is usually grown in cell culture, either in roller bottles or bioreactors. Most live vaccines are freeze-dried in order to enable storage in the refridgerator for a longer period. To this end, a so-called stabilizer is added to the culture medium. The inactivation of the vaccine virus for the production of killed vaccines is done by physical or chemical treatments that lead to denaturation of the proteins or damage of the nucleic acids. The inactivated antigen may be further purified and mixed with an adjuvant. The quality standards for vaccines are layed down in international regulations and laws. Numerous tests are performed during the different production steps and on the final product in order to warrant the quality of each batch.

Lack of evidence for claims of farmers in south-eastern Germany regarding adverse reactions ascribed to BTV-8 vaccines

Farmers in south-eastern Germany who claimed adverse reactions due to the application of BTV-8 vaccines during the compulsory vaccination programme in 2008/2009 were invited to participate in an epidemiological study to prove whether there was evidence for a plausible relationship between the immunizations and the reported symptoms. Ten farms were available for on-site visits; all other farmers (N = 120) who had registered to participate in the study were asked to complete a questionnaire and to provide evidence for the claimed adverse reactions. 25 questionnaires were returned. Although a wide range of symptoms were reported, in most cases the documentation of clinical signs, pathological alterations and fatalities was not sufficient to conclude on a causal relationship. Similarly, most of the suspected adverse events evaluated as pharmacovigilance reports had to be categorized as "unclassified due to insufficient information".

Massively parallel sequencing: a new tool in virus discovery and vaccine safety

The introduction of new sequencing technologies is revolutionizing virus discovery and providing a new means to demonstrate the safety of vaccines. Since these methods do not depend on prior assumptions of the types of viruses that may be present, they have detected viruses missed by other methods like degenerate or, family specific, PCRs. We have used massively parallel sequencing (MP-Seq) to detect new viruses in bovine serum and in the faeces of animals. When applied to sequencing the transcriptome, MP-Seq can reveal latent or silent infections. While the sequencing technology is impressive, it is bioinformatics that is the key to its successful application.

Isolation of an infectious endogenous retrovirus in a proportion of live attenuated vaccines for pets

The genomes of all animal species are colonized by endogenous retroviruses (ERVs). Although most ERVs have accumulated defects that render them incapable of replication, fully infectious ERVs have been identified in various mammals. In this study, we isolated a feline infectious ERV (RD-114) in a proportion of live attenuated vaccines for pets. Isolation of RD-114 was made in two independent laboratories using different detection strategies and using vaccines for both cats and dogs commercially available in Japan or the United Kingdom. This study shows that the methods currently employed to screen veterinary vaccines for retroviruses should be reevaluated.

Plasmid containing CpG oligodeoxynucleotides can augment the immune responses of pigs immunized with porcine reproductive and respiratory syndrome killed virus vaccine

Porcine reproductive and respiratory syndrome virus (PRRSV), the causative agent of porcine reproductive and respiratory syndrome (PRRS), causes serious health problems in swine, resulting in great economic losses to the swine industry worldwide. The porcine reproductive and respiratory syndrome (PRRS) killed virus (KV) vaccine has been widely used in China but has been linked with side effects in pigs and only partial protection. A few studies have demonstrated the immunostimulatory adjuvant effects of the synthetic CpG oligodeoxynucleotide (ODN) motifs in humans and animals. In this study, the adjuvant efficacy and the protective effects of recombinant plasmid containing CpG ODN, in combination with PRRS KV vaccine against PRRSV were evaluated. The concentration of PRRSV-specific antibodies and cytokines and the clinical parameters (body temperature, weight gain and behavior) on the challenge and post-challenge virological profiles (virus distribution in tissues and virus titers in serum at autopsy) were investigated to define the immune responses of pigs. Our findings indicated that the immune responses of the pigs immunized with plasmid containing CpG ODN and PRRS KV vaccine were stronger than those induced by PRRS KV vaccine or PBS alone. Furthermore, the protection ratios, PRRSV titers in serum samples and virus tissue distribution, all demonstrated that the plasmid containing CpG ODN could augment the immune responses and improve the protective effect of PRRSV vaccination.

[Vaccination: cost-effectiveness ratio]

Vaccination is often recognized as having an excellent cost-effectiveness ratio. Economic assessments are more and more important regarding the steadily increasing costs of vaccines. However, vaccine-specific features have to be taken in account and there is scope for improving quality of available economic evaluations of vaccination programmes. To provide clear and concise guidance for improving quality of cost-effectiveness studies in vaccinology, WHO guide has been developed. After presenting this guide, the economic evaluations of the new vaccines introduced in the Belgium calendar are reviewed.

Rotavirus gastroenteritis: Why to back up the development of new vaccines?

Rotaviruses (RVs) are the main aetiologic agent of severe acute diarrhoea in children under the age of 5, worldwide. Given that the currently available preventive measures to fight against the transmission of RV disease are not sufficiently effective, vaccination likely represents the only efficacious adapted response to the massive impact of this infection. Although the two current RV vaccines have shown good tolerance and significant efficacy to protect infant against severe RV disease, their development have raised key questions that are still unanswered regarding their cost, efficacy and safety. These two vaccines have in common the disadvantages related to the use of oral attenuated live viruses which limit their implementation in both developed and developing countries. In order to overcome these hurdles, it is important to support the development of new, non-replicating vaccines which will not suffer the potential disadvantages of the present vaccines. New approaches and other routes of administration are being tested in animal models and soon will be evaluated in humans. Among those are viral-like particle-based vaccines which have provided the most promising results. Finally, the epidemiology of the disease which differs in developed and developing countries can affect decisions about vaccine composition and delivery. The answer brought by the development of new RV vaccines could reside in developing several types of RV vaccines specifically designed to be used in different settings.

Vaccines against bluetongue in Europe

After the incursion of bluetongue virus (BTV) into European Mediterranean countries in 1998, vaccination was used in an effort to minimize direct economic losses to animal production, reduce virus circulation and allow safe movements of animals from endemic areas. Vaccination strategies in different countries were developed according to their individual policies, the geographic distribution of the incurring serotypes of BTV and the availability of appropriate vaccines. Four monovalent modified live virus (MLV) vaccines were imported from South Africa and subsequently used extensively in both cattle and sheep. MLVs were found to be immunogenic and capable of generating strong protective immunity in vaccinated ruminants. Adverse side effects were principally evident in sheep. Specifically, some vaccinated sheep developed signs of clinical bluetongue with fever, facial oedema and lameness. Lactating sheep that developed fever also had reduced milk production. More severe clinical signs occurred in large numbers of sheep that were vaccinated with vaccine combinations containing the BTV-16 MLV, and the use of the monovalent BTV-16 MLV was discontinued as a consequence. Abortion occurred in <0.5% of vaccinated animals. The length of viraemia in sheep and cattle that received MLVs did not exceed 35 days, with the single notable exception of a cow vaccinated with a multivalent BTV-2, -4, -9 and -16 vaccine in which viraemia persisted at least 78 days. Viraemia of sufficient titre to infect Culicoides insects was observed transiently in MLV-vaccinated ruminants, and natural transmission of MLV strains has been confirmed. An inactivated vaccine was first developed against BTV-2 and used in the field. An inactivated vaccine against BTV-4 as well as a bivalent vaccine against serotypes 2 and 4 were subsequently developed and used in Corsica, Spain, Portugal and Italy. These inactivated vaccines were generally safe although on few occasions reactions occurred at the site of inoculation. Two doses of these BTV inactivated vaccines provided complete, long-lasting immunity against both clinical signs and viraemia, whereas a single immunization with the BTV-4 inactivated vaccine gave only partial reduction of viraemia in vaccinated cattle when challenged with the homologous BTV serotype. Additional BTV inactivated vaccines are currently under development, as well as new generation vaccines including recombinant vaccines.

[Use of continuous human and animal cell lines for the production of viral vaccines]

History of development of safety criteria for continuous human and animal cell lines approved for manufacture of immunobiologic preparations. It was noted that current WHO documents recommend mandatory use of respective WHO's reference cell cultures (Vero-10-87 for continuous cell lines, and Wi-38 or MRC-5 for diploid cell lines) during attestation of new cell cultures proposed for the manufacturing of immunobiologic preparations. Examples of practical use of continuous cell lines (CCLs) for production of viral vaccines on industrial scale are described. On the basis of modern data most important principles were formulated which should be considered to provide safety and efficacy of vaccines produced on the CCLs.

Rapid quality control of a live attenuated Peste des petits ruminants (PPR) vaccine by monoclonal antibody based sandwich ELISA

Peste des petits ruminants (PPR) is a highly contagious and economically important viral disease of goats and sheep. A homologous Vero cell-based attenuated PPR vaccine developed in our laboratory and used extensively throughout the country, is available for control of PPR. The presently used quality control test, titration in Vero cells for PPR virus titre in vaccine batches, takes at least 6-8days to determine the quality and dose of vaccine. In this study, 74 freeze-dried PPR vaccine batches were tested simultaneously by both virus titration and PPR sandwich ELISA (S-ELISA) to correlate the titre of the vaccine virus with reactivity in S-ELISA. It was found that the vaccine batches with titre more than 10(3)TCID(50)/ml gave positive results in S-ELISA and correlated well with the virus titre of the freeze-dried vaccines. The correlation coefficient between the virus titration and S-ELISA reactivity was estimated as 0.96, indicating a high correlation between the two parameters based on 74 batches of freeze-dried PPR vaccine. The vaccine batches with titres of 3.0, 4.3, 4.5, 5.0, 6.5 and 7.0 had shown a positive reaction when tested in two-fold dilutions in S-ELISA at 1, 5, 6, 7, 8 and 9log2 titres, respectively. The test vaccine batches were found to be negative in S-ELISA when the titre of the vaccine was less than 10(3)TCID50/ml, suggesting that the vaccine could not be passed for field use. It is concluded that S-ELISA could be a preliminary tool useful for the quality control of PPR vaccine as it is rapid and easy to perform when compared to virus titration.

Pre-validation study for testing of avian viral vaccines for extraneous agents by PCR

The biological nature of vaccines imposes a permanent risk for contamination with extraneous agents. Therefore, testing of vaccines for freedom from extraneous agents is essential in the manufacturing process and quality control. Relevant methods for testing for extraneous agents of avian viral vaccines are specified in the monographs of the European Pharmacopoeia (Ph. Eur.). Currently, most of these methods involve the use of embryonated eggs or chickens. Polymerase chain reaction (PCR) is a widely used and suitable tool for the amplification and detection of extraneous nucleic acids. Different PCR assays have been developed for the application in routine testing of veterinary vaccines. However, before introduction of new methods in monographs of the Ph. Eur., they must undergo validation. Here we report about a pre-validation study performed in Official Medicines Control Laboratories (OMCLs). Diluted samples of avian infectious laryngotracheitis, avian infectious bronchitis and avian infectious bursal disease viruses have been analysed using standardised procedures and reagents. The study demonstrated that PCR methods can be transferred to other laboratories. The results also show that further work is warranted for full validation of the method.

[Vaccines, immunoglobulins, and test systems for the prevention and diagnosis of tick-borne encephalitis]

The quality of drugs used in the Russian Federation to prevent and diagnose tick-borne encephalitis (TBE) was analyzed. The TBE vaccines made in Russian were shown to be as effective as those manufactured in foreign countries and to have the similar production techniques and quality indices therefore they may be interchangeable in the population's vaccination. The specific activity of has recently increased in terms of the content of TBE virus antibodies. In Russia, a wide range of enzyme immunoassay systems have been designed and manufactured for the detection of human serum (plasma) IgM and IgG antibodies to TVE virus and for that of TBE viral antigen in the biological objects, primarily in the ticks.

Regulatory issues surrounding the temporary authorisation of animal vaccination in emergency situations: the example of bluetongue in Europe

A marketing authorisation for a veterinary vaccine is granted after the quality, safety and efficacy of the product have been assessed in accordance with legal standards. The assessment includes complete characterisation and identification of seed material and ingredients, laboratory and host animal safety and efficacy studies, stability studies, and post-licensing monitoring of field performance. This assessment may not be possible during the emergence of a new animal disease, but several mechanisms exist to allow for the availability of products in an emergency animal health situation, e.g. autogenous biologics, conditional licences, experimental and emergency use authorisations, the importation of products in use elsewhere in the world and pre-approved vaccine banks. Using the emergence of bluetongue in northern Europe as an example, the regulatory issues regarding the temporary authorisation of animal vaccination are described. Several conditions must be fulfilled before a temporary authorisation can be granted, e.g. inactivated vaccines should be used in order to exclude reversion to virulence and reassortment between vaccine viruses and/or field strains of the bluetongue virus; decision-making must be supported by scientific evidence and risk analysis; there must be a complete census of the susceptible animals that were vaccinated; vaccination protocols must be adhered to and there must be a scheme allowing for registration, delivery and follow-up of vaccination, and monitoring, analysis and, possibly, adjustment of field use of the vaccination. This temporary authorisation must be replaced by a full authorisation as quickly as possible.

Vaccination guidelines: a bridge between official requirements and the daily use of vaccines

Vaccination guidelines are non-compulsory recommendations which assist the veterinary practitioner to use vaccines efficiently. They complement the official information contained in the shortened form of the summary of product characteristics that is included in the package insert of the product. The aim of this article is to clarify the role of guidelines and examine how they can improve the use of vaccines in practical conditions. The development of vaccination guidelines is explained. Several issues are discussed: primary vaccination schedule; interference with maternally derived antibodies; duration of immunity; vaccination and ageing. Three guidelines dealing with the vaccination of cats against upper respiratory tract disease are compared, as an example. In conclusion, vaccination guidelines are essential tools to assist veterinarians in good vaccination practices. They fill the gap that exists between the official recommendations included in the regulations and the licensing dossiers and the daily use of the vaccines.

Authorisation within the European Union of vaccines against antigenically variable viruses responsible for major epizootic diseases

Antigenically variable viruses are responsible for some of the most contagious and economically important diseases that affect domestic livestock. The serious consequences of such diseases in terms of economic loss, and human and animal health, were clearly demonstrated by recent epizootics of foot and mouth disease, and outbreaks of avian influenza and bluetongue in the European Union (EU). For such diseases, government authorities need to be able to respond, if appropriate, by making use of vaccines that are suited to the epidemiological situation. The current EU regulatory framework is not well adapted for approval and maintenance of vaccines where the antigens included have to be chosen to reflect the epidemiological need. An extensive revision of the technical requirements for authorisation of veterinary medicinal products within the EU is currently underway. Additionally, a major revision of the regulations that control how such authorisations are kept up-to-date is about to start. This provides an ideal opportunity to introduce into EU legislation the concept of the 'multistrain dossier' whereby a potentially large number of approved strains may be included within a marketing authorisation and the final vaccines may be blended to include strains according to need. In addition, new strains may be added onto the marketing authorisation by means of a rapid regulatory procedure should new antigenic variants actually or potentially threaten the EU.

WHO informal consultation on the scientific basis of specifications for production and control of inactivated Japanese encephalitis vaccines for human use, Geneva, Switzerland, 1-2 June 2006

The World Health Organization (WHO) publishes technical guidance on the quality, safety and efficacy of vaccines intended to assist national regulatory authorities and manufacturers. As part of its programme, WHO convened an informal consultation to initiate revision of the WHO recommendations on the production and control of inactivated Japanese encephalitis (JE) vaccines for human use, at its headquarters in June 2006. The attendees included experts from national regulatory authorities, national control laboratories and manufacturers from around the world as per WHO policy to include all relevant stakeholders in the standards development process. Issues pertaining to recent development with inactivated JE vaccines were presented and discussed. Participants agreed upon the scientific basis of revised specifications and the inclusion of new sections on nonclinical and clinical evaluation of inactivated JE vaccines. It was agreed that the revision would cover both existing vaccines derived from mouse brain or primary cell cultures and vaccines under development in a continuous cell line (Vero).

Natural infection of cattle with an atypical `HoBi'-like pestivirus – Implications for BVD control and for the safety of biological products

During a study on Bovine Viral Diarrhoea (BVD) epidemiology in Thailand, a pestivirus was detected in serum from a calf. Comparative nucleotide sequence analysis showed that this virus was closely related to a recently described atypical pestivirus (D32/00_'HoBi') that was first isolated from a batch of foetal calf serum collected in Brazil. The results from virus neutralisation tests performed on sera collected from cattle in the herd of the infected calf, showed that these cattle had markedly higher antibody titres against the atypical pestivirus 'HoBi' than against Bovine Viral Diarrhoea Virus types 1 and 2, or Border Disease Virus. The results also supported, consequently, the results from the molecular analysis, and demonstrated that a 'HoBi'-like pestivirus had been introduced to, and was now circulating in the herd. This study is the first to report a natural infection in cattle with a virus related to this atypical pestivirus, and it suggests that this group of pestiviruses may already be spread in cattle populations. The findings have implications for BVD control and for the biosafety of vaccines and other biological products produced with foetal calf serum. Consequently, these atypical pestiviruses should be included in serological assays, and any diagnostic assay aimed at detection of pestiviruses in biological products or animals should be tested for its ability to detect them.

Vaccines and viral antigenic diversity

Antigenic diversity among ribonucleic acid (RNA) viruses occurs as a result of rapid mutation during replication and recombination/reassortment between genetic material of related strains during co-infections. Variants which have a selective advantage in terms of ability to spread or to avoid host immunity become established within populations. Examples of antigenically diverse viruses include influenza, foot and mouth disease (FMD) and bluetongue (BT). Effective vaccination against such viruses requires surveillance programmes to monitor circulating serotypes and their evolution to ensure that vaccine strains match field viruses. A formal vaccine strain selection scheme for equine influenza has been established under the auspices of the World Organisation for Animal Health (OIE) based on an international surveillance programme. A regulatory framework has been put in place to allow rapid updating of vaccine strains withoutthe need to provide full registration data for licensing the updated vaccine. While there is extensive surveillance of FMD worldwide and antigenic and genetic characterisation of isolates, there is no formal vaccine strain selection system. A coordinated international effort has been initiated to agree harmonised approaches to virus characterisation which is aimed at providing the basis for an internationally agreed vaccine matching system for FMD supported by the OIE. The emergence and spread of BT in Europe have resulted in an intensification of vaccine evaluation in terms of safety and efficacy, particularly cross-protection within and between serotypes. The most important requirement for producing vaccines against viruses displaying antigenic diversity is a method of measuring antigenic distances between strains and developing an understanding of how these distances relate to cross-protection. Antigenic cartography, a new computational method of quantifying antigenic distances between strains has been applied to human and equine influenza to examine the significance of viral evolution in relation to vaccine strains. This method is highly applicable to other important pathogens displaying antigenic diversity, such as FMD.