Genetic Diversity of Bacillus anthracis Isolates Collected From Clinical Cases and Farmland Soil in Iran, a MLVA-based Study.

Iran operates a massive vaccination scheme of farm animals against anthrax though a number of small or large epidemics are reported every year to the health authorities. Combining the conventional and molecular biology techniques, the present work intends to provide a clear epidemiological view of Bacillus anthracis in Iran. Forty-one B. anthracis isolates collected from human (No. ), cattle (No, ), sheep (No. ), goat (No. ) and soil (No. ) plus the vaccinal strain of B. anthracis Sterne F, the laboratory strain of B. anthracis Pasteur JB as well as Bacillus cereus were tested against Ba, pxO and pxO genetic markers. Once characterized at genus and species level, all the B. anthracis bacteria in the study panel were subjected to a Multiple Locus Variable Number Tandem Repeat Analysis (MLVAVNTR) genotyping system comprised of vrrA, vrrB, vrrB, vrrC, vrrC, CG, pxO and pxO loci. PCR products representing the MLVA loci from seventeen out of all tested B. anthracis isolates/strains were also sequenced. In consequence, the fragment size for vrrA, vrrB, vrrB, vrrC, vrrC, CG, pxO and pxO loci in the genome of B. anthracis Sterne F strain was identified as , , , , , , and respectively. These findings were not in support of extensive changes at genomic level in this vaccinal strain since its introduction to Razi. On the other hand, with exception of B. cereus, the Ba locus was observed in all of the examined bacteria indicating their identity as B. anthracis. Besides, the pxO locus was observed in isolates while the pxO marker was detected only in isolates. Furthermore, in MLVA genotyping, vrrC and pxO-aat with three alleles each and vrrB, vrrC and CG with two alleles displayed the highest polymorphism level contrasting vrrA, vrrB and pxO-at loci that were monomorph. On the whole, this genotyping system resulted in identification of genotypes in Iran including, A) , , , , , , , , , , , B) , , , , , , , , , , , C) , , , , , , , , , , , D) , , , , , , , , , , , E) , , , , , , , , , , , F) , , , , , , , , , , , G) F) , , , , , , , , , , . In contrast with many of the European States such as Poland with a genetically close population of B. anthracis to the Sterne F strain or African countries such as Chad where a very homogenic population of this pathogen is reported, we assume the observed heterogeneity of this pathogen in Iran detected by the present work is unexpected. The exact extent of this genetic diversity and also origin of B. anthracis in Iran is left for next studies.