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20211
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Subject: Veterinary Microbiology × Author: MOHAMMED UMAR, SHAIK × Type: Thesis ×
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    ThesisItemOpen Access
    MOLECULAR SEROTYPING OF Avibacterium paragallinarum AND DETECTION OF THE GENETIC DETERMINANTS OF ITS VIRULENCE FACTORS
    (SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA, 2021-04) MOHAMMED UMAR, SHAIK; ANAND KUMAR, P (MAJOR); LAKSHMI KAVITHA, K; ASWANI KUMAR, K
    Infectious coryza caused by Avibacterium paragallinarum is a highly contagious respiratory infection in poultry affecting the upper respiratory tract with the involvement of nasal passages, infra orbital and paranasal sinuses of chickens. In the present investigation samples were collected from suspected cases of infectious coryza in commercial poultry farms and backyard poultry in East and West Godavari districts of Andhra Pradesh, for detection of A. paragallinarum. To detect A. paragallinarum, the samples were suwith the samples. Out of total 150 samples collected, 35 samples did not yield any result specific to A. paragallinarum as they were processed after six months of their collection due to COVID 19 national lockdown. The remaining 115 samples were processed immediately after collection to detect A. paragallinarum. A total of twelve samples (B1, B2, S1, S2, J1, J2, BA1, BA2, BA3, BA4, BA5 and BA6) were found to be positive for A. paragallinarum in cultural (with satellitism) and biochemical tests. In both the culture PCR test and direct swab PCR test with oligonucleotide primers specific to A. paragallinarum, all the 12 isolates yielded a specific PCR product of 500 bp. The direct swab PCR test is found to be sensitive to detect A. paragallinarum in samples collected from infectious coryza cases, without the need of culture step, which is very helpful in rapid diagnosis. In PCR test for detecting genetic determinant of putative virulence factor haemagglutinin (hagA) only 4 isolates of A. paragallinarum viz. B1, B2, J1 and J2 yielded specific PCR product of 900 bp. However, the genetic determinant of iron acquisition protein (fur) was not detected in all the 12 isolates of A. paragallinarum. In molecular serotyping by multiplex PCR (mPCR) test using oligonucleotide primers specific to Page serotypes A, B and C, 8 isolates of A. paragallinarum viz. B1, B2, S1, S2, J1, J2, BA3 and BA4 were identified as serotype A with a PCR product of 372 bp, though the A. paragallinarum vaccine used as positive control in this study yielded PCR products of 372 bp and 800 bp. The remaining 4 isolates viz. BA1, BA2, BA5 and BA6 were identified as serotype B with a PCR product of 1100 bp. None of the A. paragallinarum isolates in this study were identified as serotype C. The results of the present investigation with the molecular serotyping indicates that serotype A and B of A. paragallinarum are circulating in East Godavari and West Godavari Districts of A.P. However, further research is required with large number of samples to identify the circulating serotypes of A. paragallinarum in A.P.