Vesicular stomatitis New Jersey virus (VSNJV) is an insect-transmitted Rhabdovirus causing vesicular disease in domestic livestock including cattle, horses, and pigs. Natural transmission during epidemics remains poorly understood, particularly in cattle, one of the most affected species during outbreaks. This study reports the first successful transmission of VSNJV to cattle by insect bite resulting in clinical disease. When infected black flies (Simulium vittatum Zetterstedt) fed at sites where VS lesions are usually observed (mouth, nostrils, and foot coronary band), infection occurred, characterized by local viral replication, vesicular lesions, and high neutralizing antibody titers (> 1: 256). Viral RNA was detected up to 9 d postinfection in tissues collected during necropsy from lesion sites and lymph nodes draining those sites. Interestingly, when flies were allowed to feed on flank or neck skin, viral replication was poor, lesions were not observed, and low levels of neutralizing antibodies (range, 1:8-1:32) developed. Viremia was never observed in any of the animals and infectious virus was not recovered from tissues on necropsies performed between 8 and 27 d postinfection. Demonstration that VSNJV transmission to cattle by infected black flies can result in clinical disease contributes to a better understanding of the epidemiology and potential prevention and control methods for this important disease.

Abstract. Horses were inoculated with Vesicular stomatitis New Jersey and Indiana viruses by routes simulating contact and vector transmission. Clinical signs, lesions, antibody development, viral shedding and persistence, and viremia were monitored. Horses were infected with both viruses by all routes as confirmed by seroconversion. Salivation, primary lesions at inoculation sites, and secondary oral lesions were the most common clinical findings. Viral shedding was most often from the oral cavity, followed by the nasal cavity; titers were highest from oral cavity samples. Virus was rarely isolated from the conjunctival sac and never from feces or blood. Development of neutralizing antibody coincided with cessation of lesion development and detection of virus by isolation. Circulating virus-specific IgM, IgG, IgA, and neutralizing antibodies developed in most animals postinoculation (PI) days 6 to 12, depending on the route of inoculation. At postmortem (PI days 12 to 15), lesions were healing, were not vesicular, and did not contain detectable virus by isolation, reverse transcriptase polymerase chain reaction, or immunohistochemistry. Numerous infiltrating lymphocytes and plasma cells suggested that lesion resolution was partially due to local immunity. Detection of viral RNA from tonsil and lymph nodes of head at necropsy suggests that these tissues play a role in the pathogenesis of the disease; molecular techniques targeting these tissues may be useful for confirming infection in resolving stages of disease. The routes of inoculation used in this study reflect the diversity of transmission routes that may occur during outbreaks and can be used to further study contact and vector transmission, vaccine development, and clarify pathogenesis of the disease in horses.

The natural transmission of vesicular stomatitis New Jersey virus (VSNJV), an arthropod-borne virus, is not completely understood. Rodents may have a role as reservoir or amplifying hosts. In this study, juvenile and nestling deer mice ( Peromyscus maniculatus) were exposed to VSNJV-infected black fly ( Simulium vittatum) bites followed by a second exposure to naive black flies on the nestling mice. Severe neurological signs were observed in some juvenile mice by 6 to 8 days postinoculation (DPI); viremia was not detected in 25 juvenile deer mice following exposure to VSNJV-infected fly bites. Both juvenile and nestling mice had lesions and viral antigen in the central nervous system (CNS); in juveniles, their distribution suggested that the sensory pathway was the most likely route to the CNS. In contrast, a hematogenous route was probably involved in nestling mice, since all of these mice developed viremia and had widespread antigen distribution in the CNS and other tissues on 2 DPI. VSNJV was recovered from naive flies that fed on viremic nestling mice. This is the first report of viremia in a potential natural host following infection with VSNJV via insect bite and conversely of an insect becoming infected with VSNJV by feeding on a viremic host. These results, along with histopathology and immunohistochemistry, show that nestling mice have widespread dissemination of VSNJV following VSNJV-infected black fly bite and are a potential reservoir or amplifying host for VSNJV.

Four free-ranging mink, Neovison vison, collected between June and September 2004 in the Fakahatchee Strand Preserve State Park (FSPSP, Florida, USA), were examined for canine distemper virus (CDV) infection. Microscopic lesions and viral inclusions consistent with CDV infection were observed in three mink. Virus isolation and reverse transcription-polymerase chain reaction performed on all mink were positive for CDV. Anecdotal records of mink observations in FSPSP suggest a postepizootic decline in the mink population followed by an apparent recovery. We recommend further research to assess the status of the Everglades mink and the impact of CDV on this and other American mink populations in Florida.

In September 2006 an outbreak of 'Bluetongue like' disease struck the cattle herds in Israel. Over 100 dairy and beef cattle herds were affected. Epizootic hemorrhagic disease virus (EHDV) (an Orbivirusclosely related to bluetongue virus (BTV)), was isolated from samples collected from several herds during the outbreaks. Following are the aims of the study and summary of the results: which up until now were published in 6 articles in peer-reviewed journals. Three more articles are still under preparation:   1. To identify the origin of the virus: The virus identified was fully sequenced and compared with the sequences available in the GenBank. It appeared that while gene segment L2 was clustered with EHDV-7 isolated in Australia, most of the other segments were clustered with EHDV-6 isolates from South-Africa and Bahrain. This may suggest that the strain which affected Israel on 2006 may have been related to similar outbreaks which occurred in north-Africa at the same year and could also be a result of reassortment with an Australian strain (Wilson et al. article in preparation). Analysis of the serological results from Israel demonstrated that cows and calves were similarly positive as opposed to BTV for which seropositivity in cows was significantly higher than in calves. This finding also supports the hypothesis that the 2006 EHD outbreak in Israel was an incursive event and the virus was not present in Israel before this outbreak (Kedmi et al. Veterinary Journal, 2011)   2. To identify the vectors of this virus: In the US, Culicoides sonorensis was found as an efficient vector of EHDV as the virus was transmitted by midges fed on infected white tailed deer (WTD; Odocoileusvirginianus) to susceptible WTD (Ruder et al. Parasites and Vectors, 2012). We also examined the effect of temperature on replication of EHDV-7 in C. sonorensis and demonstrated that the time to detection of potentially competent midges decreased with increasing temperature (Ruder et al. in preparation). Although multiple attempts were made, we failed to evaluate wild-caught Culicoidesinsignisas a potential vector for EHDV-7; however, our finding that C. sonorensis is a competent vector is far more significant because this species is widespread in the U.S. As for Israeli Culicoides spp. the main species caught near farms affected during the outbreaks were C. imicolaand C. oxystoma. The vector competence studies performed in Israel were in a smaller scale than in the US due to lack of a laboratory colony of these species and due to lack of facilities to infect animals with vector borne diseases. However, we found both species to be susceptible for infection by EHDV. For C. oxystoma, 1/3 of the Culicoidesinfected were positive 11 days post feeding.   3. To identify the host and environmental factors influencing the level of exposure to EHDV, its spread and its associated morbidity: Analysis of the cattle morbidity in Israel showed that the disease resulted in an average loss of over 200 kg milk per cow in herds affected during September 2006 and 1.42% excess mortality in heavily infected herds (Kedmi et al. Journal of Dairy Science, 2010). Outbreak investigation showed that winds played a significant role in virus spread during the 2006 outbreak (Kedmi et al. Preventive Veterinary Medicine, 2010). Further studies showed that both sheep (Kedmi et al. Veterinary Microbiology, 2011) and wild ruminants did not play a significant role in virus spread in Israel (Kedmi et al. article in preparation). Clinical studies in WTD showed that this species is highly susceptibile to EHDV-7 infection and disease (Ruder et al. Journal of Wildlife Diseases, 2012). Experimental infection of Holstein cattle (cows and calves) yielded subclinical viremia (Ruder et al. in preparation).   The findings of this study, which resulted in 6 articles, published in peer reviewed journals and 4 more articles which are in preparation, contributed to the dairy industry in Israel by defining the main factors associated with disease spread and assessment of disease impact. In the US, we demonstrated that sufficient conditions exist for potential virus establishment if EHDV-7 were introduced. The significant knowledge gained through this study will enable better decision making regarding prevention and control measures for EHDV and similar viruses, such as BTV.