Measles virus (MV) is a negative-strand RNA virus within the Morbillivirus genus of the Paramyxoviridae family. The MV transcriptional complex consists of the virus-encoded RNAdependent RNA polymerase (L), the polymerase cofactor (P), and a ribonucleoprotein template consisting of the singlestranded RNA genome and the nucleocapsid protein (N protein). N protein monomers assemble on the RNA genome during replication to form a single-start left-handed helix, protecting the genome from nuclease degradation. Encapsidation is initiated on specific sequences found within the leader RNA, drawing upon pools of soluble N-P heterodimers, whereas elongation of encapsidation occurs in an RNA sequence-independent manner (7, 24). Since genomic replication presumably is dependent upon concurrent encapsidation, functional motifs in the N protein required for genomic replication must include an RNA binding domain for the initiation of encapsidation, a binding site for P to form an N-P encapsidation complex, and N-N interaction sites required to drive nucleocapsid elongation and maintain nucleocapsid structural integrity. Additionally, N protein must contain a P binding site that is exposed on the nucleocapsid, thereby permitting the viral polymerase complex to interact with formed ribonucleoprotein templates during both transcription and genomic replication.The expression of MV N protein deletion mutants demonstrates that only the amino-terminal three-fourths of the molecule (i.e., amino acids 1 to 398) is required for the formation of organized nucleocapsid-like particles, localizing the N-N interaction domain to this highly conserved portion of the protein (1, 16). This conclusion is supported by the observation that selective proteolysis of the MV nucleocapsid can remove the C-terminal 15 kDa of the N protein while leaving nucleocapsid structural integrity and the amino-terminal 45-kDa N protein fragment intact (12). Also identified within the latter region are two sites necessary for the formation of soluble N-P complexes, localized to amino acids 4 to 188 and 304 to 373 (1). Enhanced sensitivity of the C terminus of the N protein to proteolysis is consistent with its exposure on the surface of the formed nucleocapsid. Within this exposed hypervariable domain is a third binding site for P, tentatively localized between amino acids 457 and 525 (1). For Sendai virus, the C-terminal domain of the N protein is required for template function in RNA replication assays (5) and contains a P binding site (4). Given the essential role of P in supporting viral polymerase function, a model for paramyxoviruses emerges in which P provides the link between L and N protein domains that are exposed on the nucleocapsid and that are necessary for both transcription and replication.The putative template function of the MV N protein C

Swine have been identified as the primary reservoir of pathogenic Yersinia enterocolitica (YE), but little research has focused on the epidemiology of YE at the farm level. The objective of this study was to describe the prevalence of YE in different production phases on swine farms. In this cross-sectional study, individual pigs on eight swine operations were sampled for the presence of YE. On each farm, both feces and oral-pharyngeal swabs were collected from pigs in five different production phases: gestating, farrowing, suckling, nursery, and finishing. A pig was considered positive if either sample tested positive. Samples were cultured with cold enrichment followed by isolation on selective media plates. Presumptive isolates were confirmed as YE and assayed for the presence of ail with a multiplex PCR. Of the 2,349 pigs sampled, 120 (5.1%) tested positive, and of those, 51 were ail positive (42.5% of YE isolates). On all farms, there was a trend of increasing prevalence as pigs mature. Less than 1% of suckling piglets tested positive for YE. Only 1.4% (44.4% of which were ail positive) of nursery pigs tested positive, but 10.7% (48.1% of which were ail positive) of finishing pigs harbored YE. Interestingly, gestating sows had the second highest prevalence of YE at 9.1% (26.7% of which were ail positive), yet YE was never detected from the farrowing sows. These results represent the first on-farm description of YE in U.S. herds and provide the initial step for designing future studies of YE.

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a.) Vaccination reduces Salmonella prevalence in carcasses at harvest. b.) Reduction occurs in all species of Salmonella, not just homologous/Group C1 Salmonellae. c.) Vaccination can be a valuable tool in reducing risk of foodborne disease due to Salmonella in pork. Vaccination will not interfere with serologic categorization of farms' Salmonella status. Vaccination may be considered as another potential tool for improving safety of pork by means of reducing the level of salmonella contamination of pork carcasses, and potentially ground or other fresh pork products. Commercial serologic tests may be utilized in conjunction with vaccination to evaluate the success of Salmonella reduction programs in swine.