Kawabata S, Kuwata H, Nakagawa I, Morimatsu S, Sano K, Hamada S
Department of Oral Microbiology, Osaka University Faculty of Dentistry, Suita-Osaka, Japan.
Microb Pathog. 1999 Aug;27(2):71-80. doi: 10.1006/mpat.1999.0283.
Group A streptococci (GAS) cause various diseases, from uncomplicated noninvasive, to severe invasive infections. Capsular hyaluronic acid (HA) is known to resist phagocytosis, however, interaction between HA and epithelial cells have not been clearly understood. In this study, both HA-producing wild strains and HA-nonproducing mutants were employed to examine their invasiveness into confluent cultures of HEp-2, a nonphagocytic human epithelial cell line. Invasion of HEp-2 cells by GAS strains increased over time. The hasA gene encoding hyaluronate synthase of GAS strains was inactivated by allelic replacement. It was found that hasA-inactivated mutants were internalized into HEp-2 cells more efficiently than their parent strains under various conditions in terms of incubation time and inoculum size. Taken together, these findings indicate that GAS can be internalized into HEp-2 cells with considerably high frequencies and that the presence of HA of GAS decreased the invasion efficiency.
A组链球菌（GAS）可引发多种疾病，从无并发症的非侵袭性感染到严重的侵袭性感染。已知荚膜透明质酸（HA）可抵抗吞噬作用，然而，HA与上皮细胞之间的相互作用尚未完全明确。在本研究中，使用产HA的野生菌株和不产HA的突变体来检测它们对非吞噬性人上皮细胞系HEp-2汇合培养物的侵袭能力。GAS菌株对HEp-2细胞的侵袭随时间增加。通过等位基因替换使编码GAS菌株透明质酸合酶的hasA基因失活。结果发现，在不同的孵育时间和接种量条件下，hasA基因失活的突变体比其亲本菌株更有效地内化到HEp-2细胞中。综上所述，这些发现表明GAS能够以相当高的频率内化到HEp-2细胞中，并且GAS的HA的存在降低了侵袭效率。
