ABSTRACT
@#Abstract: Objective To explore the prevalence and bacterial strains of Francisella tularensis (F. tularensis) in wild rodents in Changbai Mountain area of China, and to further understand the epidemiological characteristics of F. tularensis infections in this area. Methods Wild rodents were captured from forest and forest-edge farmland from Kuandian County and Jianshi Forest District in the Changbai Mountain area, 2012-2014. DNA was extracted from the spleen tissues of the rodents, and the fopA gene of F. tularensis in wild rodents was detected using nested PCR. The infection rates were calculated for different areas and rat species. The bacterial subspecies of positive samples were identified using type-specific primers (C1/C4), and sequencing and comparative analysis were performed. Results A total of 133 wild rodents belonging to 6 rat species were captured. Among them, eight samples from three rat species (Apodemus agrarius, Apodemus peninsulae, Tscherskia triton ) were detected positive, with the overall positive rate of 6.01%. The positive rates of F. tularensis of Ji'an and Kuandian were 7.46% and 4.54%, respectively, and there was no difference in positive rates for different regions (χ2=0.117, P=0.732) and different rat species (χ2=0.641, P=0.986). The subspecies analysis showed that the detected 8 trains of F.tularensisall belonged to F.tularensis type B (F.subspecies subsp. holarctica). Genetic evolution analysis was performed on the fopA gene sequences of three positive samples (JA56, JA33, and JA38), which clustered together with Russia strains(CP009694.1, CP044004.1) and China strains (HM371344.1, HM371343.1) F.tularensis type B, with sequence similarities ranging from 99.21% to 99.47%. Conclusions Infection of F.tularensis subsp. holarctica existed in wild rodents in Changbai Mountain area of China, which suggests the existence of F.tularensis infection risks in this area.