Association ofActinobacillus pleuropneumoniaeCapsular Polysaccharide with Virulence in Pigs
| Autor: | Mark L. Lawrence, Thomas J. Inzana, Hugo P. Veit, Aloka B. Bandara |
|---|---|
| Rok vydání: | 2003 |
| Předmět: |
DNA
Bacterial Serotype Bacterial capsule Blood Bactericidal Activity Swine Immunology Virulence Microbiology Shuttle vector medicine Animals Cloning Molecular Actinobacillus pleuropneumoniae Bacterial Capsules Antibacterial agent biology Kanamycin Bacterial Infections biology.organism_classification Phenotype Infectious Diseases Parasitology Bacteria medicine.drug |
| Zdroj: | Infection and Immunity. 71:3320-3328 |
| ISSN: | 1098-5522 0019-9567 |
| DOI: | 10.1128/iai.71.6.3320-3328.2003 |
| Popis: | The capsular polysaccharide (CP) ofActinobacillus pleuropneumoniaeis required for virulence of the bacteria in swine. However, a molecular investigation of whether the type or quantity of CP affectsA. pleuropneumoniaevirulence has not been reported. To initiate this investigation, a DNA region downstream of conserved genes required for CP export inA. pleuropneumoniaeserotype 1 was cloned and sequenced. Three open reading frames, designatedcps1A, cps1B,andcps1C, were identified that had amino acid homology to bacterial carbohydrate biosynthesis genes. A kanamycin resistance cassette (Kanr) was inserted into a 750-bp deletion spanningcps1ABor into a 512-bp deletion incps1Bonly, and the constructs were cloned in a suicide vector. The Kanrgene was then transferred into the chromosome of strain 4074 by homologous recombination to produce strain 4074Δcps1N and strain 4074Δcps1B, respectively. Strain 4074Δcps1N produced no detectable CP, but strain 4074Δcps1B made 15% of the serotype 1 CP made by the parent strain, 4074, as determined by enzyme-linked immunosorbent assay and precipitation of free CP. Thecps1ABCgenes of strain 4074 and thecps5ABCandcps5ABCDEgenes of serotype 5a strain J45 were cloned into the shuttle vector pLS88 and electroporated into 4074Δcps1N to produce 4074Δcps1N(pABcps101), 4074Δcps1N(pJMLcps53), and 4074Δcps1N(pABcps55), respectively. Strain 4074Δcps1N(pABcps101) produced about 33% of the serotype 1 CP produced by strain 4074. Strains 4074Δcps1N(pJMLcps53) and 4074Δcps1N(pABcps55) produced serotype 5a CP in similar quantity or in fourfold excess, respectively, to that produced by strain 4074. With intratracheal challenge in pigs at similar dosages, the order of virulence of strains producing serotype 1 CP (assessed by mortality, lung consolidation, hemorrhage, and fibrinous pleuritis) was the following: strain 4074 > strain 4074Δcps1N(pABcps101) ≥ strain 4074Δcps1N > strain 4074Δcps1B. Strain 4074Δcps1N(pJMLcps53) was less virulent than strain 4074Δcps1N(pABcps55). However, both strains produced serotype 5a CP in similar or greater quantities than was observed for production of serotype 1 CP by the parent strain, 4074, but were less virulent than the parent strain. Therefore, the amount of serotype 1 or 5a CP produced by isogenic strains ofA. pleuropneumoniaecorrelated with the virulence of the bacteria in pigs. However, virulence was also influenced by the type of CP produced or by its mechanism of expression. |
| Databáze: | OpenAIRE |
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