Serological response of foals to polyvalent and monovalent live-attenuated African horse sickness virus vaccines.

The research shows that when foals are vaccinated for African Horse Sickness (AHS) using either a combined or single strain vaccine, the immune response is stronger and more consistent to one strain and often weak or non-existent to other strains, suggesting that using a single strain vaccine does not enhance the immune response compared to using a combined strain vaccine.

Introduction to African Horse Sickness and its Vaccination

• African horse sickness (AHS) is a lethal disease in horses which can be prevented through vaccination.
• The use of vaccines is integral in controlling the spread of AHS to newer areas.
• In Africa, horses are given a live-attenuated (modifiable live virus) vaccine which includes different combinations of serotypes depending on the area.

Objective and Methodology of the Study

• The research set out to investigate the neutralizing antibody response of foals after they are immunized with a polyvalent MLV AHS vaccine and compare it to the response elicited by a single strain MLV AHS vaccine.
• For the research, naïve foals were immunized using either the polyvalent MLV AHS vaccine or a series of monovalent MLV vaccines which each contained a single AHS virus serotype.

Findings from the Study

• The research found that there was a considerable and consistent difference in the immunogenicity levels of the individual virus serotypes in the MLV vaccines.
• Furthermore, results demonstrated that the AHSV-1 serotype elicited the strongest immune response while responses to other serotypes tended to be variable, and often weaker or even undetectable.
• This pattern held true for both the combination and single strain vaccines, indicating that the use of a monovalent vaccine does not provide an enhanced immune response when compared with a polyvalent vaccine.