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Article
papA Gene of Avian Pathogenic Escherichia coli
Avian Diseases
  • Subhashinie Kariyawasam, Iowa State University
  • Lisa K. Nolan, Iowa State University
Document Type
Article
Publication Date
12-1-2011
DOI
10.1637/9663-011911-Reg.1
Abstract

P fimbrial adhesins may be associated with the virulence of avian pathogenic Escherichia coli (APEC). However, most APECs are unable to express P fimbriae even when they are grown under conditions that favor P fimbrial expression. This failure can be explained by the complete absence of the pap operon or the presence of an incomplete pap operon in Pap-negative APEC strains. In the present study, we analyzed the pap operon, specifically thepapA gene that encodes the major fimbrial shaft, to better understand the pap gene cluster at the genetic level. First, by PCR, we examined a collection of 500 APEC strains for the presence of 11 genes comprising the pap operon. Except for papA, all the other genes of the operon were present in 38% to 41.2% of APEC, whereas the papA was present only in 10.4% of the APEC tested. Using multiplex PCR to probe for allelic variants of papA, we sought to determine if the low prevalence of papA among APEC was related to genetic heterogeneity of the gene itself. It was determined that the papA of APEC always belongs to the F11 allelic variant. Finally, we sequenced the ‘papA region’ from two papA-negative strains, both of which contain all the other genes of the pap operon. Interestingly, both strains had an 11,104-bp contig interrupting papA at the 281-bp position. This contig harbored a streptomycin resistance gene and a classic Tn10 transposon containing the genes that confer tetracycline resistance. However, we noted that the papA gene of every papA-negative APEC strain was not interrupted by an 11,104-bp contig. It is likely that transposons bearing antibiotic resistance genes have inserted within pap gene cluster of some APEC strains, and such genetic events may have been selected for by antibiotic use.

Comments

This article is from Avian Diseases 55, no. 4 (2011): 532–538, doi:10.1637/9663-011911-Reg.1.

Copyright Owner
American Association of Avian Pathologists
Language
en
Date Available
May 8, 2013
File Format
application/pdf
Citation Information
Subhashinie Kariyawasam and Lisa K. Nolan. "papA Gene of Avian Pathogenic Escherichia coli" Avian Diseases Vol. 55 Iss. 4 (2011) p. 532 - 538
Available at: http://works.bepress.com/lisa_nolan/46/