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Ruder M.G.,Manhattan College | Lysyk T.J.,Agriculture and Agri Food Canada | Stallknecht D.E.,University of Georgia | Foil L.D.,Louisiana State University | And 4 more authors.
Vector-Borne and Zoonotic Diseases | Year: 2015

Bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV) are arthropod-transmitted viruses in the genus Orbivirus of the family Reoviridae. These viruses infect a variety of domestic and wild ruminant hosts, although the susceptibility to clinical disease associated with BTV or EHDV infection varies greatly among host species, as well as between individuals of the same species. Since their initial detection in North America during the 1950s, these viruses have circulated in endemic and epidemic patterns, with occasional incursions to more northern latitudes. In recent years, changes in the pattern of BTV and EHDV infection and disease have forced the scientific community to revisit some fundamental areas related to the epidemiology of these diseases, specifically in relation to virus-vector-host interactions and environmental factors that have potentially enabled the observed changes. The aim of this review is to identify research and surveillance gaps that obscure our understanding of BT and EHD in North America. © Copyright 2015, Mary Ann Liebert, Inc.


Ingebritson A.L.,Center for Veterinary Biologics | Roth J.A.,Iowa State University | Hauer P.J.,National Veterinary Services Laboratories
Vaccine | Year: 2010

A collection of swine, fish, and cetacean Erysipelothrix rhusiopathiae strains representing 16 serotypes was analyzed for possession of the three currently recognized surface protective antigen (spa)-types: spaA, spaB, and spaC. Polymerase chain reaction (PCR) assays and Western blotting with a SpaA-specific monoclonal antibody demonstrated that spa-type is not confined to specific serotype groups. In particular, the spa-type of strains of aquatic origin was more variable than those of terrestrial origin, and possessed the distinct ability to express more than one spa. In a cross-protection study, mice immunized with an E. rhusiopathiae serotype 2 SpaA-type strain and challenged with various E. rhusiopathiae isolates were completely protected against strains exhibiting a single homologous spa, but variably protected against strains possessing a heterologous spa or those harboring more than one spa-type.


Robbe-Austerman S.,National Veterinary Services Laboratories | Bravo D.M.,National Veterinary Services Laboratories | Harris B.,National Veterinary Services Laboratories
BMC Veterinary Research | Year: 2013

Background: Bacteriologic culture remains one of the most important methods to diagnose bovine tuberculosis despite the lengthy incubation time, significant decontamination and media expense, and high biocontainment requirements. Media selection is an important determination of culture sensitivity, and the planned discontinuation of the BACTEC 460 TB culture system has challenged veterinary diagnostic laboratories to evaluate alternatives. At the National Veterinary Services Laboratories the BACTEC MGIT 960 and 4 solid media formulations were compared with the BACTEC 460 TB system on 6,795 veterinary diagnostic specimens submitted for Mycobacterium bovis culture.Results: M. bovis was isolated from 2.6% of the samples and atypical mycobacteria from 4.4% of the samples. The BACTEC 12B media isolated significantly more M. bovis (93.1% of positive samples) than MGIT 960 media (81.9%). However, contamination rates were much higher for the MGIT media, 17-24%, compared to 7% for BACTEC, suggesting that contamination was a major cause of MGIT reduced sensitivity. Time to signal positive was 2.37 weeks (95% CI 2.24-2.5) for the MGIT, and 3.2 weeks (95% CI 3.07-3.3) for the BACTEC, both earlier than any solid media. Mycobactosel LJ failed to isolate M. bovis from primary culture. An in-house 7H11 media supplemented with calf sera, hemolyzed blood, malachite green and pyruvate recovered more M. bovis (80.6%) with the least amount of contamination of any other solid media evaluated.Conclusion: Decontamination methods may have to be optimized and or MGIT media may have to be altered to reduce contamination in veterinary samples. Despite these issues, the MGIT 960 system is still favored over the use of solid media due to decreased time to recovery and the potential for higher sensitivity. © 2013 Robbe-Austerman et al.; licensee BioMed Central Ltd.


Rhyan J.C.,National Wildlife Research Center | Nol P.,National Wildlife Research Center | Quance C.,National Veterinary Services Laboratories | Gertonson A.,Natural Resources Research Center | And 4 more authors.
Emerging Infectious Diseases | Year: 2013

Bovine brucellosis has been nearly eliminated from livestock in the United States. Bison and elk in the Greater Yellowstone Area remain reservoirs for the disease. During 1990-2002, no known cases occurred in Greater Yellowstone Area livestock. Since then, 17 transmission events from wildlife to livestock have been investigated.


Palmer M.V.,National Animal Disease Center | Thacker T.C.,National Animal Disease Center | Waters W.R.,National Animal Disease Center | Robbe-Austerman S.,National Veterinary Services Laboratories
PLoS ONE | Year: 2014

Wildlife reservoirs of Mycobacterium bovis represent serious obstacles to the eradication of tuberculosis from livestock, particularly cattle. In Michigan, USA tuberculous white-tailed deer transmit M. bovis to other deer and cattle. One approach in dealing with this wildlife reservoir is to vaccinate deer, thus interfering with the intraspecies and interspecies transmission cycles. Thirty-three white-tailed deer were assigned to one of two groups; oral vaccination with 1x108 colony-forming units of M. bovis BCG Danish (n = 17); and non-vaccinated (n = 16). One hundred eleven days after vaccination deer were infected intratonsilarly with 300 colony-forming units of virulent M. bovis. At examination, 150 days after challenge, BCG vaccinated deer had fewer gross and microscopic lesions, fewer tissues from which M. bovis could be isolated, and fewer late stage granulomas with extensive liquefactive necrosis. Fewer lesions, especially those of a highly necrotic nature should decrease the potential for dissemination of M. bovis within the host and transmission to other susceptible hosts.


Thacker T.C.,Infectious Bacterial Disease Research Unit | Robbe-Austerman S.,National Veterinary Services Laboratories | Harris B.,National Veterinary Services Laboratories | Palmer M.V.,Infectious Bacterial Disease Research Unit | Waters W.R.,Infectious Bacterial Disease Research Unit
BMC Veterinary Research | Year: 2013

Background: Mycobacteria other than M. bovis may interfere with current bovine tuberculosis diagnostic tests resulting in false positive test results. As the prevalence of M. bovis decreases in the United States, interference from other mycobacteria play an increasingly important role in preventing the eradication of M. bovis. To identify mycobacteria other than M. bovis that may be interfering with current diagnostic tests, a retrospective study was performed to identify mycobacteria isolated from clinical tissues at the National Veterinary Services Laboratories between 1 January 2004 and 9 October 2011.Results: During the study period, 2,366 mycobacteria other than M. bovis were isolated from samples submitted for clinical diagnosis of M. bovis. Fifty-five mycobacterial species were isolated during this time period. In cattle, M. avium complex, M. fortuitum/fortuitum complex, M. smegmatis, M. kansasii, and M. terrae complex were the predominate species other than M. bovis isolated from tissues submitted for culture. Mycobacteria other than M. bovis isolated from deer were predominantly M. avium complex, M. terrae/terrae complex, and M. fortuitum/fortuitum complex.Conclusions: These data provide information characterizing the species and relative prevalence of mycobacteria other than M. bovis that may interfere with current diagnostic tests. © 2013 Thacker et al.; licensee BioMed Central Ltd.


Palmer M.V.,U.S. Department of Agriculture | Thacker T.C.,U.S. Department of Agriculture | Madison R.J.,U.S. Department of Agriculture | Koster L.G.,National Veterinary Services Laboratories | And 2 more authors.
Journal of Comparative Pathology | Year: 2013

Malignant catarrhal fever (MCF) is the clinical manifestation of infection of certain ruminant species with one of a group of pathogenic gammaherpesviruses known as MCF viruses. Cattle and numerous exotic ruminant species are susceptible to clinical disease that may be sporadic or occasionally epidemic in nature. The most common MCF virus worldwide is ovine herpesvirus (OvHV)-2. Reservoir hosts such as sheep, carry and excrete OvHV-2, but do not develop clinical signs, while clinically susceptible species develop severe and often fatal disease. The existence of latent infection in clinically susceptible hosts is poorly understood, but is documented in some ruminant species. Twenty-six animals from a captive herd of white-tailed deer (Odocoileus virginianus) died and were examined from October 2006 to December 2010.Fifteen of these animals (58%) showed clinical signs and gross and microscopical lesions consistent with MCF, while 11 (42%) did not. Polymerase chain reaction (PCR) amplification yielded product consistent with OvHV-2 DNA in samples of spleen from all 26 deer. To examine the possibility of latent infection in this herd, peripheral blood mononuclear cells were examined by PCR for OvHV-2 DNA, and the test was positive in 23/32 (72%) clinically normal deer. Archived serum samples were used to examine the history of MCF exposure in the herd using a competitive enzyme-linked immunosorbent assay, which demonstrated that 10/40 (25%) deer tested had MCF viral antibodies, with nine deer being seropositive over multiple years. Combined with previous observations in deer and other species, these results suggest the existence of latent infection of white-tailed deer with OvHV-2. © 2013.


Palmer M.V.,U.S. Department of Agriculture | Thacker T.C.,U.S. Department of Agriculture | Waters W.R.,U.S. Department of Agriculture | Robbe-Austerman S.,National Veterinary Services Laboratories | And 2 more authors.
Zoonoses and Public Health | Year: 2010

Mycobacterium bovis is the cause of tuberculosis in cattle and a serious zoonotic pathogen, most commonly contracted through consumption of unpasteurized dairy products. To control this zoonosis, many countries have developed bovine tuberculosis eradication programmes. Although relatively successful, efforts are hindered in many regions by spillover from wildlife reservoirs of M. bovis to cattle. Such is the case in the United States where spillover of M. bovis from free-ranging white-tailed deer to cattle occurs. One approach to control such inter-species transmission is vaccination of wildlife. The live, attenuated human vaccine M. bovis Bacillus Calmette-Guérin (BCG) has been shown to reduce disease severity in white-tailed deer; however, vaccine persistence within tissues has also been noted. Consumption of venison containing BCG by hunters may present a public health concern as BCG exposure, although unlikely to cause disease, could cause false positive tuberculin skin test results. To examine BCG persistence further, 42 white-tailed deer were vaccinated orally or subcutaneously (SC) with BCG Danish. Three deer from each group were killed and examined at periods ranging from 2 weeks to 11 months after vaccination. BCG was recovered from orally vaccinated deer as late as 3 months after vaccination, while BCG persisted in SC vaccinated deer for as long as 9 months. At no time was BCG isolated from meat; however, prolonged persistence was seen in lymphoid organs. Although vaccine persistence was noted, especially in SC vaccinated deer, the distribution of culture-positive tissues makes human exposure through consumption unlikely. © 2010 Blackwell Verlag GmbH.


Thiele T.L.,Center for Veterinary Biologics | Stuber T.P.,National Veterinary Services Laboratories | Hauer P.J.,National Veterinary Services Laboratories
Vaccine | Year: 2013

Clostridium sordellii is a Gram positive anaerobic bacterium that causes multiple disease syndromes in both humans and animals. As with many clostridial pathogens, toxins contribute to the virulence of C. sordellii. Two large toxins have been identified: a lethal toxin (TcsL) and a hemorrhagic toxin (TcsH) which are similar in structure and function to Clostridium difficile toxin B (TcdB) and toxin A (TcdA), respectively. While TcdA, TcdB, and TcsL have been extensively studied, relatively little is known about TcsH. This study elucidated the TcsH gene sequence using whole genome sequencing, compared the genotype with toxin expression of 52 C. sordellii strains, and examined the role of TcsH in batch release potency tests required for veterinary vaccines licensed in the United States and other testing utilizing WHO standard antitoxin. Data from this study will assist in future research to clarify the TcsH contribution to the pathogenesis of C. sordellii infections and may aid in the development of improved vaccines. © 2013.


Thacker T.C.,U.S. Department of Agriculture | Palmer M.V.,U.S. Department of Agriculture | Robbe-Austerman S.,National Veterinary Services Laboratories | Stuber T.P.,National Veterinary Services Laboratories | Waters W.R.,U.S. Department of Agriculture
Veterinary Microbiology | Year: 2015

Mycobacterium bovis (M. bovis) causes tuberculosis in white-tailed deer (WTD). Natural infection of WTD with M. bovis is most closely mimicked by instilling inoculum into palatine tonsillar crypts. One hundred fifty days after intratonsillar inoculation, M. bovis was cultured from 30 tissues originating from 14 deer. Whole-genome sequencing (WGS) was performed on the original inoculum, single colonies subcultured from the original inoculum, and M. bovis isolated from each culture positive tissue. Single nucleotide polymorphisms (SNP) were identified by comparing the derived sequences to the reference strain AF2122/97. Results indicate that the majority of the SNPs that were identified were homogeneous between the inoculum and the isolates from the tissues. The majority of individual tissues had different WGS genotypes from each other, suggesting that dissemination of M. bovis beyond the initial site of infection may require few mycobacteria representing a bottleneck. © 2015.

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