Studies with equine infectious anemia virus: transmission attempts by mosquitoes and survival of virus on vector mouthparts and hypodermic needles, and in mosquito tissue culture.

The research investigates the transmission of equine infectious anemia virus (EIAV) through mosquitoes and its survival on the mouthparts of mosquitoes, in hypodermic needles, as well as in mosquito tissue cultures. It concludes that these vectors were not successful in transmitting the disease and the virus survival was limited to just a few hours or days.

Biological and Mechanical Transmission Trials

• The team attempted to transmit EIAV through mosquitoes belonging to the species Psorophora columbiae and Aedes sollicitans to ponies acutely infected with the virus. However, these attempts were unsuccessful.
• On examining these vectors, EIAV antigens were identified in Aedes sollicitans immediately after they fed on an unwell pony but were not found 14 days after feeding, indicating the virus did not persist.
• Psorophora columbiae mosquitoes had the EIAV antigen detected 24 hours after feeding on an acutely infected pony, slightly persisting up to 14 days after feeding, but did not facilitate active transmission.

Survival of Virus on Hypodermic Needles

• The investigation extended to determining the survival of EIAV on hypodermic needles. The virus was detectable on the needles at 25 C for 96 hours. However, it was not detected 120 hours after these needles were immersed in EIAV solutions, demonstrating the temporal limitation of the virus’ survival outside a host.

Survival of Virus on Mosquito Mouthparts

• The survival of the virus was also assessed on the mouthparts of mosquitoes post-feeding on a virus-rich medium. EIAV was detected up to 1 hour after feeding but was not detectable 4 hours after feeding, suggesting that the virus does not persist long enough on the insect’s mouthparts to facilitate successful transmission to a new host.

Virus in Mosquito Tissue Culture

• The research also investigated the survival and multiplication of the virus in mosquito tissue culture. Culex pipiens quinquefasciatus Say ovarian cells were able to maintain the infectivity of EIAV for up to 10 weekly passages. Yet, no evidence suggested that the virus was able to multiply in such conditions.

In summary, the research concludes that mosquitoes are an unlikely vector for EIAV transmission due to their inability to maintain and propagate the virus for long periods. Furthermore, the virus’ survival outside the host is temporally limited, reducing its spread via means such as contaminated hypodermic needles.