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Occurrence of V-factor (NAD) independent strains of Haemophilus paragallinarum
M Mouahid1, M Bisgaard, A J Morley
1Department of Medical Microbiology, University of Marburg, Germany.
Abstract:
Strains of Bisgaard taxon 31, isolated from chickens in South Africa suffering from a respiratory disease with clinical symptoms and gross lesions similar to infectious coryza, showed great phenotypical similarities with Haemophilus paragallinarum infection except for NAD requirement, beta-galactosidase activity and maltose fermentation. Deoxyribonucleic acid-deoxyribonucleic acid hybridization confirmed a high level of genetic relatedness (DNA binding value, 89%) with Haemophilus paragallinarum. Guanine + cytosine content and genome size data also support the classification of taxon 31 strains within the species Haemophilus paragallinarum.
Insights
New research identifies Bisgaard taxon 31 strains from South African chickens as genetically similar to Haemophilus paragallinarum, despite minor phenotypic differences. This finding aids in understanding avian respiratory diseases.
Area of Science:
- Veterinary Microbiology
- Avian Pathology
Background:
- Bisgaard taxon 31 strains were isolated from chickens in South Africa exhibiting respiratory disease.
- Clinical signs and lesions resembled infectious coryza, a common poultry disease.
Purpose of the Study:
- To characterize Bisgaard taxon 31 strains phenotypically and genetically.
- To determine the taxonomic relationship between Bisgaard taxon 31 and Haemophilus paragallinarum.
Main Methods:
- Phenotypic analysis including NAD requirement, beta-galactosidase activity, and maltose fermentation.
- Deoxyribonucleic acid-deoxyribonucleic acid (DNA-DNA) hybridization to assess genetic relatedness.
- Guanine + cytosine content and genome size determination.
Main Results:
- Bisgaard taxon 31 strains showed phenotypic similarities to Haemophilus paragallinarum, with notable exceptions.
- DNA-DNA hybridization revealed a high genetic relatedness (89% DNA binding value) with Haemophilus paragallinarum.
- Guanine + cytosine content and genome size supported classification within Haemophilus paragallinarum.
Conclusions:
- Bisgaard taxon 31 strains are genetically closely related to Haemophilus paragallinarum.
- These findings support the classification of Bisgaard taxon 31 within the species Haemophilus paragallinarum.
- This research contributes to the understanding of causative agents of avian respiratory diseases.