M E S '9 8 - University of Georgia College of Veterinary Medicine

in Oregon. The objective of this study was todetermine if white-tailed deer in Georgia carryE. coli O157:H7.During summer 1997, more than 300 freshdeer fecal samples were collected from theground at five Georgia wildlife areas. Duringautumn 1997, nearly 400 fecal samples werecollected directly from hunter-killed deer at thesame locations plus an additional area. Fecalsamples were cultured for E. coli O157:H7.All samples collected from the groundwere culture-negative. Three samples (0.8%)collected directly from deer were positive forE. coli O157:H7. The three isolates were from77 deer sampled (3.8%) during November atone area. Two of the three isolates had identicalDNA fingerprints. All three isolates producedShiga-like toxins 1 and 2. Samples offrozen processed meat from the three positivedeer were culture-negative for E. coliO157:H7.Results of this study suggest that the overallprevalence of E. coli O157:H7 is low infree-ranging deer; however, there may be focalareas where deer harbor the bacteria. Cattlewere present in the vicinity where the positivedeer were found, but they also were present atother sites where deer were culture-negative.Additionally, the results suggest that contaminationof meat did not occur during field dressingand processing of the three deer carryingE. coli O157:H7.John R. Fischer, Tong Zhao, andMichael P. Doyle *jfischer@calc.vet.uga.edu* Food Science and TechnologyExperimental Infection of Deer Mice withVesicular Stomatitis VirusVesicular stomatitis (VS) is a viral diseaseof cattle, horses, and swine, that causes substantialeconomic losses to livestock producers.The epidemiology of this disease is currentlyundefined, but it is suspected that the virus ismaintained in a vertebrate/insect vector cycleinvolving wildlife. To determine if native wildrodents may be involved in this cycle, a pilotstudy involving experimental infection of 100deer mice (Peromyscus maniculatus) withvesicular stomatitis virus (VSV), New Jersey(NJ) serotype, was performed. The virus usedin this study was originally isolated from sandflies collected on Ossabaw Island, Georgia.Viremia was detected in infected mice duringpostinoculation days one through three. Viruswas isolated from various tissues from 96 of100 mice from postinoculation days onethrough seven, and virus isolation results wereconfirmed by polymerase chain reaction(PCR), immunohistochemical detection ofvirus in tissues, and in situ hybridization ofviral RNA in tissues. Following this pilotstudy, a series of experiments were conductedto compare the outcome of infection in deermice with two different strains of VSV-NJ. TheOssabaw Island strain was compared with aVSV-NJ isolate from a recent VS outbreak(1995) in Colorado, with emphasis on developmentof viremia, clinical outcome, and distributionof virus in tissues. The Colorado strain ofVSV-NJ produced a significantly higher levelof viremia and caused central nervous systemdisease sooner than the Ossabaw Island strainof VSV-NJ. Further experiments using thisdeer mouse model are planned to investigatethe effects of route of inoculation and dose ofvirus on development and extent of viremia,the effects of pregnancy on infection, andeventually, the potential for viremic deer miceto infect appropriate insect vectors. Resultsfrom this study provide the first evidence that avertebrate host can become viremic and thusprovide a source of VSV-NJ to biting arthropodsand eventually livestock. Results alsoindicate that the deer mouse can provide avaluable research tool to further study vectorcompetence of suspected biting insect species.David E. Stallknecht, Elizabeth W. Howerth,and Todd E. Cornishdstall@calc.vet.uga.edu20