DEMONSTRATION OF INFECTIOUS TAURA-SYNDROME VIRUS IN THE FECES OF SEA-GULLS COLLECTED DURING AN EPIZOOTIC IN TEXAS

Laughing gulls Larus atricilla were observed feeding on diseased shrim p Penaeus vannamei during an epizootic of the Taura syndrome virus (TS V) at a south Texas farm in May 1995. Fresh fecal samples were collect ed from a gull roosting site on a pond lever where gulls that fed on d iseased shrimp had roosted overnight. The feces samples were tested fo r the presence of TSV by injection bioassay. A cell-free clarified hom ogenate of the fecal material was injected into indicator P. vannamei, and the shrimp were observed for 9 d. Cumulative mortalities of the t wo replicate groups of indicator shrimp were 45% and 70%. Moribund ind icator shrimp collected and preserved for histological examination exh ibited lesions pathognomonic for acute-phase infections by TSV. The pr esence of TSV in the induced lesions was confirmed with in situ hybrid ization with cDNA probes specific for a portion of the TSV genome. The presence of infectious TSV in the gulls' feces supports the hypothesi s that these birds are a probable transport vector of the virus within and among nearby shrimp farms.