An Evaluation of the Efficacy of Four Currently Used Sheep Pox Vaccines Against a Contemporary Virulent Strain.

BACKGROUND/

OBJECTIVES

Sheep pox, a highly contagious disease, is prevalent in Africa and Asia, with sporadic outbreaks in Europe, and inflicts tremendous economic losses. Vaccination represents the primary and most effective prevention method. The genetic diversity of circulating SPPV strains worldwide is poorly studied, and vaccine selection is typically guided by the availability of a particular vaccine. In this study, four sheep pox vaccines, including the RM65, KSGP 0240, KSGP ARRIAH, and NISKHI ARRIAH vaccines, were evaluated against a contemporary virulent strain circulating in Asia.

METHODS

The level of antibodies in the blood serum was determined using the ELISA and microneutralization assay. Blood samples and nasal swabs were obtained for PCR examination. Comprehensive clinical and postmortem pathological examinations were conducted.

RESULTS

The body temperature of all experimental animals remained within the physiological norm, with no clinical manifestations, local reactions, viremia, or necropsy pathological lesions, demonstrating the effectiveness and safety of the vaccines used against the contemporary virulent strain. Furthermore, immunization was associated with the formation of neutralizing and specific antibodies in all vaccinated groups post vaccination, with a significant increase in their levels after challenge, indicating a high level of immunogenicity. The NISKHI ARRIAH vaccine exhibited statistically significant superiority over the other vaccinated groups. However, the unvaccinated control group demonstrated post-challenge moderate-to-severe clinical signs, postmortem lesions, with high levels of virus shedding, and lower levels of neutralizing and specific antibodies, compared with the vaccinated groups.

CONCLUSIONS

Our study results indicate that the experimental group immunized with the NISKHI ARRIAH vaccine exhibited the initial and most substantial immune response, maintaining the highest antibody levels on the 28th day after vaccination in comparison to the other studied vaccines.