Acute phase protein expression during elephant endotheliotropic herpesvirus-1 viremia in Asian elephants (Elephas maximus).

Infection of Asian elephants (Elephas maximus) with elephant endotheliotropic herpesvirus (EEHV) can be associated with rapid, lethal hemorrhagic disease and has been documented in elephant herds in human care and in the wild. Recent reports describe real-time quantitative polymerase chain reaction (qPCR) assays used to monitor clinically ill elephants and also to detect subclinical EEHV1 infection in apparently healthy Asian elephants. Acute phase proteins have been demonstrated to increase with a variety of infectious etiologies in domesticated mammals but have not yet been described in elephants. In addition, the immune response of Asian elephants to EEHV1 infection has not been described. In this study, whole blood and trunk wash samples representing repeated measures from eight elephants were examined for the presence of EEHV1 using a qPCR assay. Elephants were classified into groups, as follows: whole blood negative and positive and trunk wash negative and positive. Serum amyloid A (SAA) and haptoglobin (HP) levels were compared between these groups. A significant difference in SAA was observed with nearly a threefold higher mean value during periods of viremia (P=0.011). Higher values of SAA were associated with >10,000 virus genome copies/ml EEHV1 in whole blood. There were no significant differences in HP levels, although some individual animals did exhibit increased levels with infection. These data indicate that an inflammatory process is stimulated during EEHV1 viremia. Acute phase protein quantitation may aid in monitoring the health status of Asian elephants.