Intestinal samples collected from 43 commercial broiler and 33 commercial turkey flocks from all regions of the United States during 2005 and 2006 were examined for the presence of astrovirus, rotavirus, reovirus, and coronavirus by reverse transcription-polymerase chain reaction (PCR), and for the presence of groups 1 and 2 adenovirus by PCR. Phylogenetic analysis was performed to further characterize the viruses and to evaluate species association and geographic patterns. Astroviruses were identified in samples from 86% of the chicken flocks and from 100% of the turkey flocks. Both chicken astrovirus and avian nephritis virus (ANV) were identified in chicken samples, and often both viruses were detected in the same flock. Turkey astrovirus type-2 and turkey astrovirus type-1 were found in 100% and 15.4% of the turkey flocks, respectively. In addition, 12.5% of turkey flocks were positive for ANV. Rotaviruses were present in 46.5% of the chicken flocks tested and in 69.7% of the turkey flocks tested. Based upon the rotavirus NSP4 gene sequence, the chicken and turkey origin rotaviruses assorted in a species-specific manner. The turkey origin rotaviruses also assorted based upon geographical location. Reoviruses were identified in 62.8% and 45.5% of chicken and turkey flocks, respectively. Based on the reovirus S4 gene segment, the chicken and turkey origin viruses assorted separately, and they were distinct from all previously reported avian reoviruses. Coronaviruses were detected in the intestinal contents of chickens, but not turkeys. Adenoviruses were not detected in any chicken or turkeys flocks. Of the 76 total chicken and turkey flocks tested, only three chicken flocks were negative for all viruses targeted by this study. Most flocks were positive for two or more of the viruses, and overall no clear pattern of virus geographic distribution was evident. This study provides updated enteric virus prevalence data for the United States using molecular methods, and it reinforces that enteric viruses are widespread in poultry throughout the United States, although the clinical importance of most of these viruses remains unclear.

The prokaryotic ribosome is an important target of antibiotic action. We determined the X-ray structure of the aminoglycoside kasugamycin (Ksg) in complex with the Escherichia coli 70S ribosome at 3.5-Å resolution. The structure reveals that the drug binds within the messenger RNA channel of the 30S subunit between the universally conserved G926 and A794 nucleotides in 16S ribosomal RNA, which are sites of Ksg resistance. To our surprise, Ksg resistance mutations do not inhibit binding of the drug to the ribosome. The present structural and biochemical results indicate that inhibition by Ksg and Ksg resistance are closely linked to the structure of the mRNA at the junction of the peptidyl-tRNA and exit-tRNA sites (P and E sites).Translation initiation is the rate-limiting step of protein synthesis and is a central target for the global regulation of gene expression 1 . In bacteria, modulation of translation initiation has been attributed to sequences and secondary structures within mRNAs. These include the strength of the Shine-Dalgarno (SD) sequence, the identity of the initiation codon, the presence or absence of secondary structures in the 5′ leader sequence and the presence of A/U-rich sequences recognized by ribosomal protein S1 (refs. 2 ,3 ). However, the role of the sequence between the SD and the initiation codon remains unclear, despite reports showing large effects of this region on gene expression 2,4,5 . This stretch of mRNA traverses the universally conserved ribosomal E site within the 30S subunit during initiation 6,7 .The aminoglycoside Ksg has been reported to inhibit initiation of translation by blocking initiator transfer RNA binding to the 30S subunit 8-12 . Ksg is produced by the bacterium Streptomyces kasugaensis 13 and has been used clinically in the treatment of Pseudomonas aeruginosa infections 14 . The antibiotic is currently used in the treatment of the fungus Pyricularia oryzae in rice fields 13 .