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Characterization of the diversity of Haemophilus parasuis field isolates by the use of serotyping and genotyping

Oliveira, S. and Blackall, P.J. and Pijoan, C. (2003) Characterization of the diversity of Haemophilus parasuis field isolates by the use of serotyping and genotyping. American Journal of Veterinary Research, 64 (4). pp. 435-442.

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Publisher URL: http://www.avma.org

Abstract

Objective—To characterize the genetic diversity of Haemophilus parasuis field isolates with regard to serovar, herd of origin, and site of isolation.

Sample population—Isolates of H parasuis obtained from pigs in 15 North American herds and multi-farm systems.

Procedure—98 H parasuis isolates were genotyped with the enterobacterial repetitive intergeneic consensus based-polymerase chain reaction (ERIC-PCR) technique and serotyped via agar gel precipitation test. Genomic fingerprints were analyzed and dendrograms were constructed to identify strains from the same serovar group, herd of origin, or isolation site and to evaluate the genetic variability within these categories.

Results—Serovar 4 (39%) and nontypeable (NT) isolates (27%) were most prevalent. Thirty-four distinct strains were identified among the 98 isolates, using a 90% similarity cutoff. Strains from serovar 4 and NT isolates had high genetic diversity (12 and 18 strains, respectively). One to 3 major clusters of prevalent strains could be identified in most of the evaluated herds. Haemophilus parasuis strains isolated from the upper respiratory tract were either serovar 3 or NT isolates. Potentially virulent strains (isolated from systemic sites) were either serovars 1, 2, 4, 5, 12, 13, or 14, or NT isolates.

Conclusions and Clinical Relevance—Although H parasuis had high genetic diversity overall, only a few strains caused disease in these herds. The ERIC-PCR technique was more discriminative than serotyping, and a broad genetic variety was observed within particular serovar groups.

Item Type:Article
Additional Information:© American Veterinary Medical Association.
Keywords:Haemophilus parasuis; serotyping; genotyping.
Subjects:Science > Biology > Genetics
Veterinary medicine > Diseases of special classes of animals > Swine
Veterinary medicine > Veterinary bacteriology
Deposited On:26 Mar 2004
Last Modified:09 Sep 2010 23:57

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