Anti-rabies humoral immune response in cats after concurrent vs separate vaccination against rabies and feline leukaemia virus using canarypox-vectored vaccines.

OBJECTIVES: Some expert groups recommend that cats should be vaccinated with non-adjuvanted feline leukaemia virus (FeLV) and rabies vector vaccines, which, in the European Union, are currently not licensed for concurrent use and have to be administered at least 14 days apart (different from the USA) and thus at separate visits, which is associated with more stress for cats and owners. The aim of this study was to assess the anti-rabies antibody response in cats after vaccination against rabies and FeLV at concurrent vs separate (4 weeks apart) visits using two canarypox-vectored vaccines (Purevax Rabies and Purevax FeLV; Boehringer Ingelheim) and to evaluate the occurrence of vaccine-associated adverse events (VAAEs). METHODS: Healthy FeLV antigen-negative client-owned kittens (n = 106) were prospectively included in this randomised study. All kittens received primary vaccinations against rabies (week 0) and FeLV (weeks 4 and 8). After 1 year, the study group (n = 52) received booster vaccinations against rabies and FeLV concurrently at the same visit (weeks 50-52). The control group (n = 54) received booster vaccinations against rabies (weeks 50-52) and FeLV (weeks 54-56) separately. Anti-rabies virus antibodies (anti-RAV Ab) were determined by fluorescent antibody virus neutralisation assay at weeks 4, 50-52 and 54-56, and compared between both groups using a Mann-Whitney U-test. RESULTS: Four weeks after the first rabies vaccination, 87/106 (82.1%) kittens had a titre ⩾0.5 IU/ml and 19/106 (17.9%) had a titre <0.5 IU/ml. Four weeks after the 1-year rabies booster, all cats had adequate anti-RAV Ab according to the World Organisation for Animal Health (⩾0.5 IU/ml), and the titres of the study group (median = 14.30 IU/ml) and the control group (median = 21.39 IU/ml) did not differ significantly (P = 0.141). VAAEs were observed in 7/106 (6.6%) cats. CONCLUSIONS AND RELEVANCE: Concurrent administration of Purevax FeLV and Purevax Rabies vector vaccines at the 1-year booster does not interfere with the development of anti-RAV Ab or cause more adverse effects and thus represents a better option than separate vaccination visits for cats and owners.

Evaluation of concurrent vaccinations with recombinant canarypox equine influenza virus and inactivated equine herpesvirus vaccines.

Despite vaccination, equine influenza virus (EIV) and equine herpesvirus (EHV) infections still cause highly contagious respiratory diseases in horses. Recently, concurrent vaccination with EIV and EHV was suggested as a new approach; however, there have been no reports of concurrent vaccination with recombinant canarypox EIV and inactivated EHV vaccines. In this study, we aimed to compare the EIV-specific immune responses induced by concurrent administrations of a recombinant canarypox EIV vaccine and an inactivated bivalent EHV vaccine with those induced by a single recombinant canarypox EIV vaccine in experimental horse and mouse models. Serum and peripheral blood mononuclear cells (PBMCs) were collected from immunized animals after vaccination. EIV-specific serum antibody levels, serum hemagglutinin inhibition (HI) titers, and interferon-gamma (IFN-γ) levels were measured by enzyme-linked immunosorbent assay, HI assay, and quantitative polymerase chain reaction, respectively. Concurrent EIV and EHV vaccine administration significantly increased IFN-γ production, without compromising humoral responses. Our data demonstrate that concurrent vaccination with EIV and EHV vaccines can enhance EIV-specific cellular responses in horses.

Concurrent vaccination of goats with foot and mouth disease (FMD) and peste des petits ruminants (PPR) booster vaccines.

Foot and mouth disease (FMD) remains subclinical and self-limiting in small ruminants, but risk of spread of infection to susceptible cohorts is of great epidemiological significance; therefore, small ruminants must be included in vaccination campaigns in FMD endemic regions. Three groups of goats already immunized against peste des petits ruminants (PPR) were vaccinated with FMD and PPR vaccines alone or concurrently. The specific antibody response against three FMD virus strains and PPR virus were evaluated by competitive enzyme-linked immunosorbent assay (cELISA). Goats concurrently vaccinated with PPR + FMD vaccines had significantly (p < 0.05) higher antibody titers to two serotypes of FMD virus at 28, 45, and 60 days post-immunization compared to goats vaccinated with FMD vaccine alone, while goats vaccinated with PPR vaccines alone or PPR + FMD vaccines concurrently showed similar antibody kinetics against PPR virus up till 60 days post-vaccination. Overall, antibody kinetic curves for all three tested strains of FMD virus and PPR virus were similar in vaccinated groups during the course of experiment.

Concurrent vaccination of pigs with type 1 and type 2 porcine reproductive and respiratory syndrome virus (PRRSV) protects against type 1 PRRSV but not against type 2 PRRSV on dually challenged pigs.

The objective of the present study was to evaluate the effect of concurrent vaccination of pigs with both type 1 and type 2 porcine reproductive and respiratory syndrome virus (PRRSV) vaccine against heterologous dual challenge of both genotypes and compare with single vaccination of pigs against heterologous single challenge of both genotypes. Pigs were administered both type 1 and type 2 PRRSV vaccine concurrently into separate anatomical sites at 28 days of age and inoculated intranasally with both genotypes at 63 days of age. Neutralizing antibodies (NA) were not detected in any pigs in any group (NA titer <2 log2) throughout the experiment. In addition, concurrent vaccination of pigs with two PRRSV genotypes had significantly lower numbers of type 1 and type 2 PRRSV-specific interferon-γ secreting cells (IFN-γ-SC) compared to vaccination of pigs with type 1 or type 2 PRRSV only. Despite the decreased induction of type 1 PRRSV-specific IFN-γ-SC, concurrent vaccination is still able to reduce type 1 PRRSV viremia whereas the decreased induction of type 2 PRRSV-specific IFN-γ-SC by concurrent vaccination correlates with lack of reduction of type 2 PRRSV viremia after dual challenge. The results of this study demonstrated that concurrent vaccination of pigs with two PRRSV genotypes is able to reduce the levels of type 1 PRRSV viremia and lung lesions but not able to reduce the levels of type 2 PRRSV viremia and lung lesions.