Proteolytic cleavage of VP2, an outer capsid protein of African horse sickness virus, by species-specific serum proteases enhances infectivity in Culicoides.

The research explores how proteins in different animal species can affect the infectivity of African horse sickness virus (AHSV) in a specific insect, Culicoides variipennis, which plays a role in the spread of the virus.

Study Design and Methodology

• The researchers collected purified African horse sickness virus (AHSV) and used it in a blood meal fed to adult female Culicoides variipennis, insects from a susceptible colony in the UK.
• The blood meal consisted of blood sourced from various animals—sheep, cows, horses, donkeys, and dogs—each spiked with a serotype of the AHSV virus, AHSV9.
• The study aimed to compare the infectivity levels produced in C. variipennis after consumption of these different blood meals.

Findings of the Research

• The infectivity levels of the virus, i.e., its ability to establish an infection in the insect vector, varied significantly depending on the source of the blood sample in the meal.
• By comparing the protein profiles obtained from AHSV9 after incubation with blood of different species, they discovered that some species-specific serum proteases—a type of enzyme that cleaves proteins—were able to cleave the outer capsid protein of the virus, known as VP2.
• The researchers found a correlation between the presence of these specific serum proteases and an increase in the virus’s infectivity for the insect vector. In other words, when AHSV was exposed to blood samples containing these proteases, it increased the ability of the virus to infect the C. variipennis insects.

Implications of the Study

• The results of this study suggest that the species-specific serum proteases inherent in different animals’ blood could influence the spread and infection of AHSV.
• This could have important implications for controlling and preventing the spread of AHSV, especially as it affects a variety of animals and can significantly affect populations of livestock like horses and cattle.
• Further research could explore how modifying these serum proteases could potentially reduce infectivity of AHSV, providing a potential avenue for prevention and intervention in managing this disease.