Astroviruses are frequently associated with enteric diseases in poultry, being isolated from cases of runting-stunting syndrome (RSS) of broiler chickens, poult enteritis complex (PEC), and poult enteritis mortality syndrome (PEMS) of turkeys. Currently, five types of avian astrovirus have been identified: turkey astroviruses 1 and 2 (TAstV-1, TAstV-2), avian nephritis virus (ANV), chicken astrovirus (CAstV) and duck astrovirus (DAstV). The objective of this study was to molecularly characterize the different types of avian astroviruses circulating in commercial poultry. Sequence analysis of a region of ORF2, which encodes the capsid precursor protein associated with serotype and viral pathogenesis, revealed extensive variation in amino acid sequence within each subtype: TAstV-2 (81.5%-100%), ANV (69.9%-100%), and CAstV (85.3%-97.9%). However, this region was more conserved in TAstV-1's (96.2%-100%). Furthermore, a novel astrovirus was detected in chicken samples and found to be <64% similar to ANV and <30.6% similar to CAstV. The results of this study underline the great genetic variability of avian astroviruses and indicate that there are most likely multiple serotypes of each avian astrovirus circulating in commercial poultry.

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Comparative sequence analysis of six independent chicken and turkey parvovirus nonstructural (NS) genes revealed specific genomic regions with 100% nucleotide sequence identity. A polymerase chain reaction (PCR) assay with primers targeting these conserved genome sequences proved to be highly specific and sensitive to detecting parvoviruses in experimentally infected chickens. In a nationwide survey, a total of 138 field enteric samples from poultry flocks were tested by PCR for parvovirus presence. Of the tested chicken samples that were collected in 54 farms, 77% showed the presence of parvovirus, while 78% of the turkey samples that were received from 29 farms were parvovirus positive. For the first time, our data clearly demonstrate that parvoviruses are widely distributed in commercial poultry flocks in the United States. The high prevalence of parvovirus infection in birds from enteric disease-affected flocks suggests a potential role of these viruses in the etiology of enteric disease of poultry. Phylogenetic analyses comparing NS gene segments showed that most of the chicken and turkey parvovirus isolates formed separate phylogenetic groups. These findings suggest that the chicken and turkey parvoviruses might have diverged from a common ancestor and have subsequently undergone host-specific adaptation.

Borrelia burgdorferi strain B31 MI commonly loses one or more of its complement of 21 extrachromosomal plasmids during normal handling procedures and during genetic manipulations. Certain plasmid losses cause an inability or reduction in the ability of spirochetes to infect mice. In the current study, nine strains of spirochetes with varying plasmid profiles were used to identify plasmids necessary for nymphal tick infection. Nymphal ticks were artificially fed the nine spirochete strains as well as the parental strain containing a full complement of plasmids. The capillary fed nymphs were allowed to feed on mice for at least 63 h and then examined for the presence of spirochetes in their guts and salivary glands. All spirochete strains tested were able to infect ticks guts, but to different degrees. We determined that the plasmids lp5, lp28-1, and cp9 were not required for infecting tick guts, whereas loss of lp25 and lp28-4 was associated with reduced gut infectivity. A reduction in the ability of spirochetes to invade salivary glands was seen in bacteria that did not have lp28-1, whereas cp9 was not required for salivary gland infection. This study has pinpointed specific plasmids whose absence is deleterious to infecting nymphal tick guts and salivary glands.