关键词: 猪附红细胞体, 16S rRNA基因, 系统进化分析

Abstract: The Eperythrozoon suis genomic DNA was extracted from blood samples with Eperythrozoon infection based on the light and electron microscopic examinations. The 16S rRNA gene was amplified by using the universal eubacterial primers. The PCR product was cloned and sequenced. A sequence of 1 469 base-pair(bp) was obtained from each of the three naturally infected pigs at the different pig farm. Each of the three sequences was compared to that derived from GenBank using BLASTn, and the closest sequence was 16S rRNA gene of E. suis Illinois strain, with a similarity of 95%. These findings suggested that the E.suis isolated from pigs in Guangdong, China is a new genetype E. suis. The phylogenetic analysis based on the 16S rRNA genes sequences of E.suis Guangdong strain and other related organisms, including Eperythrozoon and Haemobartonella, some species of Mycoplasmatales and Rickettsiales in GenBank database, showed that all species in Eperythrozoon and haemobartonella formed a separate and distinct phylogenetic branch, these haemotrophic bacteria were more closely related to Mycoplasma spp.in Mycoplasmatales (75%)than to Anaplasma, Bartonella and Ehrlichia spp in Rickettsiales (70%). Our results indicated that Eperythrozoon and Haemobartonella genera should be reclassified in Mycoplasma genus of Mycoplasmatales to reflect their actual phylogenetic relations.

Key words: Eperythrozoon suis, 16S rRNA gene, phylogenetic analysis