Screening for bacterial DNA in the hard tick Hyalomma marginatum (Ixodidae) from Socotra Island (Yemen): detection of Francisella-like endosymbiont

Abstract

Thirty-four adult ticks collected from livestock on Socotra Island (Yemen) were identified as <em>Hyalomma marginatum</em> using traditional morphological characteristics. Morphological identification was confirmed for all the collected specimens using a molecular approach targeting a fragment of the mitochondrial gene 12S rRNA. All the specimens were examined for the presence of tick-borne pathogens and the tick endosymbiont <em>Candidatus </em>Midichloria mitochondrii using polymerase chain reaction. Three specimens out of the 34 analyzed tested positive to the presence of <em>Francisella </em>spp. leading to the first detection of these bacteria in <em>H. marginatum</em> on Socotra Island. The phylogenetic analyses conducted on a 660 bp fragment of the ribosomal gene 16S rRNA of <em>Francisella </em>spp. (including<em> F. philomiragia</em> as outgroup, the four subspecies of <em>F. tularensis</em> and the <em>Francisella</em>-like endosymbiont of ticks) confirm that the newly detected <em>Francisella </em>strains cluster into the <em>Francisella</em>-like endosymbionts of ticks. Interestingly, the detected <em>Francisella</em>-like endosymbiont, shows a different genotype to that previously isolated from <em>H. marginatum</em> collected in Bulgaria. No specimen was positive for the presence of <em>Rickettsia </em>spp., <em>Coxiella burnetii</em>, <em>Borrelia burgdorferi </em>or <em>M</em>. <em>mitochondrii</em>.