Eleven laboratories collaborated to determine the periodic prevalence of Salmonella in a population of dogs and cats in the United States visiting veterinary clinics. Fecal samples (2,965) solicited from 11 geographically dispersed veterinary testing laboratories were collected in 36 states between January 2012 and April 2014 and tested using a harmonized method. The overall study prevalence of Salmonella in cats (3 of 542) was <1%. The prevalence in dogs (60 of 2,422) was 2.5%. Diarrhea was present in only 55% of positive dogs; however, 3.8% of the all diarrheic dogs were positive, compared with 1.8% of the nondiarrheic dogs. Salmonella-positive dogs were significantly more likely to have consumed raw food (P = 0.01), to have consumed probiotics (P = 0.002), or to have been given antibiotics (P = 0.01). Rural dogs were also more likely to be Salmonella positive than urban (P = 0.002) or suburban (P = 0.001) dogs. In the 67 isolates, 27 unique serovars were identified, with three dogs having two serovars present. Antimicrobial susceptibility testing of 66 isolates revealed that only four of the isolates were resistant to one or more antibiotics. Additional characterization of the 66 isolates was done using pulsed-field gel electrophoresis and whole-genome sequencing (WGS). Sequence data compared well to resistance phenotypic data and were submitted to the National Center for Biotechnology Information (NCBI). This study suggests an overall decline in prevalence of Salmonella-positive dogs and cats over the last decades and identifies consumption of raw food as a major risk factor for Salmonella infection. Of note is that almost half of the Salmonella-positive animals were clinically nondiarrheic.

Abstract. Late in 1991, an enveloped RNA virus (now called porcine reproductive and respiratory syndrome [PRRS] virus) was identified as the etiologic agent for mystery swine disease. In 1992, laboratory procedures for the diagnosis of this disease evolved rapidly, and veterinary diagnosticians started applying these tests to field cases. This report is written from the perspective of veterinary laboratory diagnosticians and utilizes 3 case studies to define the advantages and disadvantages of the various available diagnostic laboratory PRRS test procedures in different clinical situations. The diagnostic procedures currently used in our laboratory for investigating PRRS are pathologic examination, serologic testing, fluorescent antibody (FA) testing, and virus isolation. Interstitial pneumonia, characterized by mononuclear cell infiltration of alveolar walls with normal airway epithelium, is a hallmark lesion for the disease, especially in neonatal pigs with respiratory distress. Interstitial pneumonia is not a specific lesion and must be coupled with other tests to verify PRRS virus infection. Demonstration of seroconversion is helpful, especially in sows that have experienced reproductive failure. The indirect FA test detects antibody sooner than the serum neutralization test and will likely become the serologic test of choice. The direct FA test on fresh tissue utilizes monoclonal antibody and is useful for investigating PRRS virus-associated pneumonia. Virus isolation utilizing swine alveolar macrophages has also been a useful diagnostic procedure. All of the above tests have been universally unrewarding when applied to aborted, mummified, or stillborn piglets.

Porcine reproductive and respiratory syndrome virus (PRRSV) continues to be a major problem in the pork industry worldwide. The limitations of current PRRSV vaccines require the development of a new generation of vaccines. One of the key steps in future vaccine development is to include markers for diagnostic differentiation of vaccinated animals from those naturally infected with wild-type virus. Using a cDNA infectious clone of type 1 PRRSV, this study constructed a recombinant green fluorescent protein (GFP)-tagged PRRSV containing a deletion of an immunogenic epitope, ES4, in the nsp2 region. In a nursery pig disease model, the recombinant virus was attenuated with a lower level of viraemia in comparison with that of the parental virus. To complement the marker identification, GFP and ES4 epitope-based ELISAs were developed. Pigs immunized with the recombinant virus lacked antibodies directed against the corresponding deleted epitope, but generated a high-level antibody response to GFP by 14 days post-infection. These results demonstrated that this recombinant marker virus, in conjunction with the diagnostic tests, enables serological differentiation between marker virus-infected animals and those infected with the wild-type virus. This rationally designed marker virus will provide a basis for further development of PRRSV marker vaccines to assist with the control of PRRS. INTRODUCTIONPorcine reproductive and respiratory syndrome (PRRS) is the most economically significant disease of swine worldwide. It is characterized by late-term reproductive failure in sows and severe pneumonia in neonatal pigs. Since its emergence in domestic swine in the 1980s, PRRS has resulted in immense economic losses to the swine industry, with recent costs in the USA of at least US$600 million annually (Neumann et al., 2005). The aetiological agent of PRRS is a small, enveloped virus (PRRSV) containing a single, positive-stranded RNA genome. PRRSV belongs to the family Arteriviridae, which includes equine arteritis virus (EAV), lactate dehydrogenase-elevating virus and simian hemorrhagic fever virus (Snijder & Meulenberg, 1998). Nucleotide sequence comparisons have shown that PRRSV can be divided into distinct European (type 1) and North American (type 2) genotypes (Allende et al., 1999;Nelsen et al., 1999).The PRRSV genome is about 15 kb in length and contains nine open reading frames (ORFs). The 39 end of the genome encodes four membrane-associated glycoproteins (GP2, GP3, GP4 and GP5, encoded by subgenomic mRNAs 2a, 3, 4 and 5), two unglycosylated membrane proteins (E and M; encoded by subgenomic mRNAs 2b and 6) and a nucleocapsid protein (N; encoded by subgenomic mRNA 7) Mounir et al., 1995;Bautista et al., 1996;Mardassi et al., 1996;Meng et al., 1996;Meulenberg & Petersen-den Besten, 1996;Wu et al., 2001Wu et al., , 2005. The replicase-associated genes, ORF1a and ORF1b, situated at the 59 end of the genome, represent almost 75 % of the viral genome. The ORF1ab-encoded polyprotein pp1ab is predicted to be cleaved at 12 sites ...

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