Abstract
Justificativa e objetivos: Apesar de ser utilizado como um método de genotipagem para diferentes microrganismos, poucos estudos relatam a utilização de Multiple-Locus Variable Number of Tandem Repeats Analysis (MLVA) para análise da diversidade clonal do Helicobacter pylori. O objetivo deste estudo foi determinar a variabilidade genética de cepas de H. pylori pelo MLVA no sul do Brasil. Métodos: 95 amostras de DNA de H. pylori foram obtidas a partir de biópsias gástricas de pacientes H. pylori-positivos provenientes de duas cidades do sul do Brasil e a diversidade genética das cepas foi avaliada pelo método MLVA utilizando eletroforese em gel de agarose. Para a seleção dos loci a serem analisados neste estudo, foi realizada uma análise in silico de 12 loci previamente descritos na literatura. Resultados: A partir da análise in silico, apenas quatro loci foram considerados viáveis para a análise genotípica das cepas, resultando em 90 cepas distribuídas em oito grupos diferentes e cinco cepas órfãs. Conclusões: Apesar de o método MLVA permitir fazer inferências acerca da diversidade genética de uma população, nossos resultados mostraram que os métodos de genotipagem do H. pylori devem ser criticamente avaliados antes de serem utilizados nessa região do Brasil.
Highlights
Genotyping is an important tool in epidemiology studies, enabling the identification of predominant clones and geospatial distribution.[1]
On the basis of a previous study performed by Guo et al (2011), we used the Vector NTI Suite 8® software to perform an in silico analysis of the 12 loci (VNTR 180, 263, 557, 607, 614, 1801, 2181, 2457, 2576, 5062, 5282 and 5581) in order to identify the annealing sites of the primers in the whole genomes of H. pylori strains 26695 (AE000511.1), J99 (AE001439.1) and HPAG1 (CP000241.1), which are available in the GenBank database, National Center of Biotechnology Information (NCBI)
To further understand this result, a new in silico analysis using other strains of H. pylori (G27, F57, B8, HUP-B14 and Shi470), which have sequenced genomes, was performed in addition to those already referenced in this study
Summary
Genotyping is an important tool in epidemiology studies, enabling the identification of predominant clones and geospatial distribution.[1] Helicobacter pylori have been correlated to a variety of gastric disorders such as chronic gastritis, peptic ulcer and gastric cancer.[2,3] A comparison of the genome sequence of strains of H. pylori indicates that there is significant genetic variation, mainly due to the high rates of mutation and genetic recombination in this microorganism.[2,4] This genetic diversity allows for its adaptation to several unfavorable host conditions.[5,6] genotyping studies have demonstrated a relationship among microorganisms’ and their host’s genetics, permitting the inference of a potential co-evolution.[7] Multiple-Locus Variable-Number Tandem-Repeats Analysis (MLVA) is largely used for genotyping, including prokaryotes and eukaryotes, few studies have standardized MLVA for H. pylori.[8,9,10] The aim of this study was to evaluate 12 previously described loci for the genotyping of H. pylori using gastric biopsies of H. pylori-positive patients in southern Brazil.[9]. Despite its use as a genotyping method for different microorganisms, few studies have reported the use of Multiple-Locus Variable Number of Tandem Repeats Analysis (MLVA) for the analysis of the clonal diversity of Helicobacter pylori. Conclusion: Despite MLVA method allow make inferences about the genotypic diversity of a population, our results showed that H. pylori genotyping methods should be critically evaluated prior to their use in this region of Brazil
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