Data_Sheet_3_Horizontal transfer and phylogenetic distribution of the immune evasion factor tarP.PDF

Methicillin-resistant Staphylococcus aureus (MRSA), a major human pathogen, uses the prophage-encoded tarP gene as an important immune evasion factor. TarP glycosylates wall teichoic acid (WTA) polymers, major S. aureus surface antigens, to impair WTA immunogenicity and impede host defence. However, tarP phages appear to be restricted to only a few MRSA clonal lineages, including clonal complexes (CC) 5 and 398, for unknown reasons. We demonstrate here that tarP-encoding prophages can be mobilized to lysogenize other S. aureus strains. However, transfer is largely restricted to closely related clones. Most of the non-transducible clones encode tarM, which generates a WTA glycosylation pattern distinct from that mediated by TarP. However, tarM does not interfere with infection by tarP phages. Clonal complex-specific Type I restriction-modification systems were the major reasons for resistance to tarP phage infection. Nevertheless, tarP phages were found also in unrelated S. aureus clones indicating that tarP has the potential to spread to distant clonal lineages and contribute to the evolution of new MRSA clones.

耐甲氧西林金黄色葡萄球菌（Methicillin-resistant Staphylococcus aureus, MRSA）是一类重要的人类致病菌，其借助前噬菌体编码的tarP基因作为关键免疫逃逸因子。TarP可对作为金黄色葡萄球菌主要表面抗原的壁磷壁酸（wall teichoic acid, WTA）聚合物进行糖基化修饰，以此削弱WTA的免疫原性并阻碍宿主防御机制。然而，目前尚不明确为何携带tarP基因的噬菌体仅局限于少数MRSA克隆谱系，包括克隆复合体（clonal complexes, CC）5和398。本研究证实，携带tarP基因的前噬菌体可被动员并溶原化其他金黄色葡萄球菌菌株，但该转移过程大多仅局限于亲缘关系较近的克隆株。多数不可转导的克隆株均编码tarM基因，该基因所介导的WTA糖基化模式与TarP所产生的模式截然不同，但tarM基因并不会干扰携带tarP噬菌体的感染。克隆谱系特异性I型限制修饰系统是导致菌株对携带tarP噬菌体感染产生抗性的主要原因。尽管如此，研究人员仍在亲缘关系较远的金黄色葡萄球菌克隆株中发现了携带tarP的噬菌体，这表明tarP基因具备向远缘克隆谱系传播的潜力，并可能推动新型MRSA克隆株的演化。