Dataset Information

Molecular characterization of Mycoplasma synoviae isolated from broiler chickens of West Azarbaijan province by PCR of vlhA gene.

ABSTRACT: Mycoplasma synoviae (MS) is a pathogen responsible for respiratory and locomotor disorders and causes major economic losses in poultry industry. Early and accurate diagnosis of MS infection plays a major role in control of the infection. This study was conducted to characterize Iranian field isolates of MS isolated from broiler chickens of West Azarbaijan province (Northwest of Iran), and differentiate them from vaccine strain MS-H. Two encoding genes, 16S rRNA and vlhA were employed. PCR results using primers related to 16s rRNA and vlhA genes were analyzed and compared. Out of 21 field samples, eight samples (38.0%) were positive using both sets of primers. Amplified products of vlhA gene were sequenced for MS strain identification. The results showed that Iranian field isolates of MS had high nucleotide and amino acid similarity. Iranian field isolates were distinct from vaccine strain MS-H. Results presented in this study showed that characterization of field isolates of MS by sequencing of vlhA gene and is beneficial for strain typing and differentiating them from vaccine strain. To our knowledge, this is the first study characterizing vlhA gene of MS isolates from broiler chickens in the West Azarbaijan province.

SUBMITTER: Ghaniei A

PROVIDER: S-EPMC5094171 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Molecular characterization of Mycoplasma synoviae isolated from broiler chickens of West Azarbaijan province by PCR of vlhA gene.

Ghaniei Abolfazl A

Veterinary research forum : an international quarterly journal 20160915 3

Mycoplasma synoviae (MS) is a pathogen responsible for respiratory and locomotor disorders and causes major economic losses in poultry industry. Early and accurate diagnosis of MS infection plays a major role in control of the infection. This study was conducted to characterize Iranian field isolates of MS isolated from broiler chickens of West Azarbaijan province (Northwest of Iran), and differentiate them from vaccine strain MS-H. Two encoding genes, 16S rRNA and vlhA were ...[more]

PMID: 27872715

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Project description:Mycoplasma synoviae depends on its adhesin VlhA to mediate cytadherence to sialylated host cell receptors. Allelic variants of VlhA arise through recombination between an assemblage of promoterless vlhA pseudogenes and a single transcription promoter site, creating lineages of M. synoviae that each express a different vlhA allele. The predicted full-length VlhA sequences adjacent to the promoter of nine lineages of M. synoviae varying in avidity of cytadherence were aligned with that of the reference strain MS53 and with a 60-a.a. hemagglutinating VlhA C-terminal fragment from a Tunisian lineage of strain WVU1853(T). Seven different sequence variants of an imperfectly conserved, single-copy, 12-a.a. candidate cytadherence motif were evident amid the flanking variable residues of the 11 total sequences examined. The motif was predicted to adopt a short hairpin structure in a low-complexity region near the C-terminus of VlhA. Biotinylated synthetic oligopeptides representing four selected variants of the 12-a.a. motif, with the whole synthesized 60-a.a. fragment as a positive control, differed (P<0.01) in the extent they bound to chicken erythrocyte membranes. All bound to a greater extent (P<0.01) than scrambled or irrelevant VlhA domain negative control peptides did. Experimentally introduced branched-chain amino acid (BCAA) substitutions Val3Ile and Leu7Ile did not significantly alter binding, whereas fold-destabilizing substitutions Thr4Gly and Ala9Gly tended to reduce it (P<0.05). Binding was also reduced to background levels (P<0.01) when the peptides were exposed to desialylated membranes, or were pre-saturated with free sialic acid before exposure to untreated membranes. From this evidence we conclude that the motif P-X-(BCAA)-X-F-X-(BCAA)-X-A-K-X-G binds sialic acid and likely mediates VlhA-dependent M. synoviae attachment to host cells. This conserved mechanism retains the potential for fine-scale rheostasis in binding avidity, which could be a general characteristic of pathogens that depend on analogous systems of antigenically variable adhesins. The motif may be useful to identify previously unrecognized adhesins.

Project description:BackgroundIn Mycoplasma synoviae, type strain WVU 1853, a single member of the haemaglutinin vlhA gene family has been previously shown to be expressed. Variants of vlhA are expressed from the same unique vlhA promoter by recruiting pseudogene sequences via site-specific recombination events, thus generating antigenic variability. Using a bacterial stock of M. synoviae WVU 1853 that had been colony purified thrice and maintained in our laboratory at low passage level, we previously identified a vlhA gene-related partial coding sequence, referred to as MS2/28.1. The E. coli-expressed product of this partial coding sequence was found to be immunodominant, suggesting that it might be expressed.ResultsReverse transcription-PCR amplification (RT-PCR), using a sense primer located at the 5'-end region of the expected vlhA transcript and a reverse primer located at the 3' end of MS2/28.1 coding sequence, yielded a consistent amplification product showing that MS2/28.1 was indeed transcribed. Nucleotide sequence analysis of the RT-PCR product identified an 1815-nucleotide full-length open reading frame (ORF), immediately preceded by a nucleotide sequence identical to that previously reported for expressed vlhA genes. PCR amplifications using genomic DNA isolated from single colonies further confirmed that the full-length ORF of MS2/28.1 was located downstream of the unique vlhA promoter sequence. The deduced 604-amino acid (aa) sequence showed a perfect sequence identity to the previously reported vlhA expressed genes along the first 224 residues, then highly diverged with only 37.6% aa identity. Despite the fact that this M. synoviae clone expressed a highly divergent and considerably shorter C-terminal haemagglutinin product, it was found to be expressed at the surface of the bacterium and was able to haemagglutinate chicken erythrocytes. Importantly, the E. coli-expressed C-terminal highly divergent 60 residues of MS2/28.1 proved haemagglutination competent.ConclusionsIn contrast to the previously characterized vlhA expressed variants, MS2/28.1 displayed a highly divergent sequence, while still able to haemagglutinate erythrocytes. Overall, the data provide an indication as to which extent the M. synoviae vlhA gene could vary its antigenic repertoire.

Dataset Information

Molecular characterization of Mycoplasma synoviae isolated from broiler chickens of West Azarbaijan province by PCR of vlhA gene.

Publications

Molecular characterization of <i>Mycoplasma synoviae</i> isolated from broiler chickens of West Azarbaijan province by PCR of <i>vlhA</i> gene.

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