The growth of African horse-sickness virus in embryonated hen eggs and the transmission of virus by Culicoides variipennis Coquillett (Diptera, Ceratopogonidae).

The study investigates the growth of African Horse Sickness virus in 7-day-old embryonated hen eggs and the subsequent transmission of the virus by Culicoides variipennis midges, establishing their potential role as biological vectors of the virus in laboratory conditions.

Methodology

• 7-day-old embryonated hen eggs were deliberately infected with African Horse Sickness virus using two methods: yolk sac and intravenous route.
• The growth and severity of the virus were examined and quantified by determining the viral titre in the blood of the infected embryos.

Findings

• The African Horse Sickness virus was able to grow and reach a high titre in the blood of the infected embryos, suggesting successful infection and replication of the virus in this model.
• Culicoides variipennis midges, that fed on the blood of these infected eggs, contracted the virus.
• After a period of 7 days at temperatures of 26 – 27 degrees Celsius, these infected midges were able to transmit the virus to uninfected eggs. This demonstrated that not only could the midges pick up the virus, but they could also subsequently transfer it, thus playing the role of a vector.

Conclusion

• Based on these findings, it was concluded that Culicoides variipennis can be considered a biological vector of the African Horse Sickness virus under laboratory conditions.
• This study provided a groundwork for understanding the transmission cycle of the African Horse Sickness virus, offering insights into potential intervention strategies to minimize the spread of the disease.