[The application of MALDI-ToF mini-sequencing for detecting genetically altered versions of cholera agent]

The genetically altered modifications of V.cholerae eltor are characterized by occurrence of single-nucleotide polymorphisms in gene ctxB. To detect these modifications the technique is proposed based on mini-sequencing with MALDI-ToF by of products of reaction with selected probes adjacent to 115 and 203 positions of gene mentioned previously. The mass-spectrometry analysis of the results of reaction of mini-sequencing of strains of V.cholerae eltor isolated during epidemic complications at the territory of the Siberia and the Far East revealed mass-specters corresponding to values of molecular masses of probes (ctxB115, ctxB203) and those complementary completed to points of corresponding replacements (T/C) of didesoxinucleotides (ddTTP, ddCTP). For analyzed strains of V.cholerae eltor isolated in the 1970s, elongation is establishedfor both probes by didesoxinucleotide that testifies presence in their genome ctxB3 allele with thymine in 115 and 203 positions, distinctive for typical representatives of V.cholerae eltor. For V.cholerae eltor, isolated in 1990s, hybridization to points of replacement of didesoxicytosine and presence of ctxB1 allele with cytosine at analyzed positions, distinctive to vibrio of classic biovars. This allele is detected in genome of one of modifications of atypical genetically altered clones ofV.cholerae eltor. This technique, by its sensitivity and specificity, matches direct sequencing of gene ctxB of strains of V.cholerae eltor and proves promising for analysis of other valuable single-nucleotide polymorphisms.