CACHE VALLEY AND POTOSI VIRUSES (BUNYAVIRIDAE) IN WHITE-TAILED DEER (ODOCOILEUS-VIRGINIANUS) - EXPERIMENTAL INFECTIONS AND ANTIBODY PREVALENCE IN NATURAL-POPULATIONS

Cache Valley virus (CVV) and Potosi virus (POTV) are two closely relat ed mosquito-borne viruses (Bunyaviridae: Bunyamwera group) that appear to circulate in several regions of the United States, especially the Midwest. We determined the prevalence of specific neutralizing antibod ies to both viruses in Indiana white-tailed deer and conducted infecti on experiments to assess whether deer could serve as an vertebrate-amp lifying host. Cross-infection experiments also were carried out to inv estigate the level of antibody cross-reactivity and cross-protection b etween the two viruses. The seroprevalence rate was high for both CVV (> 66%) and POTV (> 43%) in adult deer statewide. Antibodies neutraliz ing CVV were more common among deer harvested in the northern part of Indiana whereas the prevalence of POTV antibodies suggested a more sou thern distribution for this virus. Experimental infections of captive deer showed that they may serve as amplifying hosts for either virus. Deer infected with CVV or POTV developed a 1-3-day viremia with 3.0 an d 4.1 log(10) plaque-forming units/ml mean peak titers, respectively. However, significant levels of antibody cross-reactivity between the t wo viruses were observed. Viremia was lower and shorter when animals i mmune to either CVV or POTV were cross-infected with the alternate vir us and antibody responses following cross-infections resembled origina l antigenic sin with higher titers of antibodies against the primary a gent.