Pena H F J, Gennari S M, Dubey J P, Su C
Department of Preventive Veterinary Medicine and Animal Health, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, Av. Prof. Dr. Orlando Marques de Paiva, 87, CEP 05508-270, São Paulo, Brazil.
Int J Parasitol. 2008 Apr;38(5):561-9. doi: 10.1016/j.ijpara.2007.09.004. Epub 2007 Sep 21.
Recent studies found that isolates of Toxoplasma gondii from Brazil were biologically and genetically different from those in North America and Europe. However, to date only a small number of isolates have been analysed from different animal hosts in Brazil. In the present study DNA samples of 46 T. gondii isolates from cats in 11 counties in São Paulo state, Brazil were genetically characterised using 10 PCR restriction fragment length polymorphism markers including SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 and Apico. An additional marker, CS3, that locates on chromosome VIIa and has previously been shown to be linked to acute virulence of T. gondii was also used to determine its association to virulence in mice. Genotyping of these 46 isolates revealed a high genetic diversity with 20 genotypes but no clonal Type I, II or III lineage was found. Two of the 46 isolates showed mixed infections. Combining genotyping data in this study with recent reported results from chickens, dogs and cats in Brazil (total 125 isolates) identified 48 genotypes and 26 of these genotypes had single isolates. Four of the 48 genotypes with multiple isolates identified from different hosts and locations are considered the common clonal lineages in Brazil. These lineages are designated as Types BrI, BrII, BrIII and BrIV. These results indicate that the T. gondii population in Brazil is highly diverse with a few successful clonal lineages expanded into wide geographical areas. In contrast to North America and Europe, where the Type II clonal lineage is overwhelmingly predominant, no Type II strain was identified from the 125 Brazil isolates. Analysis of mortality rates in infected mice indicates that Type BrI is highly virulent, Type BrIII is non-virulent, whilst Type BrII and BrIV lineages are intermediately virulent. In addition, allele types at the CS3 locus are strongly linked to mouse-virulence of the parasite. Thus, T. gondii has an epidemic population structure in Brazil and the major lineages have different biological traits.
最近的研究发现，来自巴西的刚地弓形虫分离株在生物学和遗传学上与北美和欧洲的分离株不同。然而，迄今为止，巴西仅对少量来自不同动物宿主的分离株进行了分析。在本研究中，使用包括SAG1、SAG2、SAG3、BTUB、GRA6、c22 - 8、c29 - 2、L358、PK1和Apico在内的10种聚合酶链反应限制性片段长度多态性标记，对来自巴西圣保罗州11个县猫的46株刚地弓形虫分离株的DNA样本进行了遗传特征分析。另外一个位于VIIa染色体上且先前已证明与刚地弓形虫急性毒力相关的标记CS3，也被用于确定其与小鼠毒力的关联。对这46株分离株的基因分型显示出高度的遗传多样性，共有20种基因型，但未发现克隆I型、II型或III型谱系。46株分离株中有2株显示混合感染。将本研究中的基因分型数据与巴西近期报道的鸡、狗和猫的结果（共125株分离株）相结合，共鉴定出48种基因型，其中26种基因型只有单个分离株。从不同宿主和地点鉴定出的48种多分离株基因型中有4种被认为是巴西常见的克隆谱系。这些谱系被指定为BrI型、BrII型、BrIII型和BrIV型。这些结果表明，巴西的刚地弓形虫种群高度多样化，有少数成功的克隆谱系扩展到广泛的地理区域。与北美和欧洲不同，在北美和欧洲II型克隆谱系占绝对优势，而在这125株巴西分离株中未鉴定出II型菌株。对感染小鼠死亡率的分析表明，BrI型具有高毒力，BrIII型无毒力，而BrII型和BrIV型谱系具有中等毒力。此外，CS3位点的等位基因类型与寄生虫的小鼠毒力密切相关。因此，刚地弓形虫在巴西具有流行的种群结构，主要谱系具有不同的生物学特性。
Zotero 插件