Genetic variability of the P120' surface protein gene of Mycoplasma hominis isolates recovered from Tunisian patients with uro-genital and infertility disorders

<p>Abstract</p> <p>Background</p> <p>Among the surface antigens of <it>Mycoplasma hominis</it>, the P120' protein was previously shown to elicit a subtle antibody response and appears to be relatively conserved. To get better insight into the evolution of this protein, we analysed the genetic variability of its surface exposed region in 27 <it>M. hominis </it>isolates recovered from the genital tract of Tunisian patients with infertility disorders.</p> <p>Methods</p> <p>All specimens were processed for culture and PCR amplification of the N-terminal surface exposed region of p120' gene. PCR products were sequenced to evaluate the genetic variability, to test for adaptive selection, and to infer the phylogenetic relationship of the <it>M. hominis </it>isolates.</p> <p>Results</p> <p>Sequence analysis showed a total of 25 single nucleotide polymorphisms distributed through 23 polymorphic sites, yielding 13 haplotypes. All but one mutation were confined within three distinct regions. Analysis of the amino acid-based phylogenetic tree showed a predominant group of 17 closely related isolates while the remaining appear to have significantly diverged.</p> <p>Conclusion</p> <p>By analysing a larger sample of <it>M. hominis </it>recovered from patients with urogenital infections, we show here that the P120' protein undergoes substantial level of genetic variability at its surface exposed region.</p

Characterization of a variant <it>vlhA </it>gene of <it>Mycoplasma synoviae</it>, strain WVU 1853, with a highly divergent haemagglutinin region

Abstract Background In 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. Results Reverse 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. Conclusions In contrast to the previously characterized vlhA expressedvariants, 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.</p

Representative illustration of PCR amplification of the 510-bp fragment of

<p><b>Copyright information:</b></p><p>Taken from "Genetic variability of the P120' surface protein gene of isolates recovered from Tunisian patients with uro-genital and infertility disorders"</p><p>http://www.biomedcentral.com/1471-2334/7/142</p><p>BMC Infectious Diseases 2007;7():142-142.</p><p>Published online 5 Dec 2007</p><p>PMCID:PMC2225410.</p><p></p> M: 100 bp molecular size ladder, lanes 1 and 7: PG21 strain (positive control), lane 2: No DNA with Mhp120' primers (negative control), lanes 3–6: Mhp120' primers with DNA from ATCC 33530 (lane 3), ATCC 19989 (lane 4), ATCC 15531 (lane 5), and UuipT3 (lane 6), lanes 8–19: isolates

Multiple alignment of the deduced amino acid sequences of the P120'surface exposed region of isolates (Mh1 to Mh27) relative to the reference strain PG21

<p><b>Copyright information:</b></p><p>Taken from "Genetic variability of the P120' surface protein gene of isolates recovered from Tunisian patients with uro-genital and infertility disorders"</p><p>http://www.biomedcentral.com/1471-2334/7/142</p><p>BMC Infectious Diseases 2007;7():142-142.</p><p>Published online 5 Dec 2007</p><p>PMCID:PMC2225410.</p><p></p> Dots indicate identical residues. The 3 regions where amino acid changes which tend to occur are underlined