Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 23, 1994
Publication Date: November 1, 1994
Citation: Mecham, J.O., Nunamaker, R.A. 1994. Complex interactions between vectors and pathogens: culicoides variipennis sonorensis (diptera: ceratopogonidae) infection rates with bluetongue viruses.. Journal of Medical Entomology 31(6):903-907. Interpretive Summary: C. v. sonorensis is the primary insect vector responsible for the transmission of bluetongue (BLU) virus to sheep, cattle and other ruminants in North America. Infection of the vector with the virus, replication of the virus in the vector, and transmission of the virus to a susceptible host are probably determined by characteristics of the vector, the virus, and the vertebrate host. Colonized C.v. sonorensis have been maintained as colonies at ABADRL since 1957. These flies are being used to investigate factors that determine susceptibility of the vector to BLU virus infections. Five serotypes of BLU virus have been isolated in North America and the incidence of BLU disease may be influenced by the serotype circulating at that time. In this study, we investigated the infection of flies from two colonies of C. v. sonorensis with the five North American serotypes of BLU virus. Infection was determined by a sensitive antigen-capture ELISA. The results showed that there was a significant effect of the serotype on infection of C. v. sonorensis with BLU virus. There was also interaction between the colonies and the virus serotypes (different serotypes gave different infection rates in the two colonies). These findings indicate that caution must be exercised when interpreting all vector competency data, since different vector populations can respond quite differently to different virus populations. This information will be of value in designing experiments to characterize both viral and vector determinants that affect vector competency for bluetongue.
Technical Abstract: Two laboratory colonies of Culicoides variipennis sonorensis Wirth & Jones were allowed to take blood meals containing the five U.S. serotypes (2, 10, 11, 13, and 17) of bluetongue (BLU) virus. After 14 d of extrinsic incubation, the flies were assayed for the presence of virus using an antigen capture enzyme-linked immunosorbent assay (ELISA). There was a significant effect of the serotype on infection of C. v. sonorensis with BLU virus. There was no significant difference in infection of the two colonies when averaged across the five BLU virus treatments. However, there was a statistically significant interaction between the colonies and the virus serotypes, which was demonstrated by a higher rate of infection of the AA colony with BLU virus serotype 13 and a higher rate of infection of the AK colony with BLU virus serotype 11.