Nisseiken Co., Ltd., Tokyo, Japan; Faculty of Agriculture and Aquaculture, University of Cuu Long, Vinh Long, Viet Nam.
Nippon Institute for Biological Science, Tokyo, Japan.
Vet Microbiol. 2024 Nov;298:110291. doi: 10.1016/j.vetmic.2024.110291. Epub 2024 Oct 28.
We have analyzed the capsule (CPS) and the lipopolysaccharide O-Antigen (O-Ag) biosynthesis loci of fifteen field isolates of Actinobacillus pleuropneumoniae, including eleven North American and four Japanese ones, reactive to antisera against serovars 3, 6, 8 and/or 15. Ten North American isolates amplified a serovar 6-indicative fragment derived from the capsular loci, whereas one North American isolate and all four Japanese isolates amplified the serovar 6-indicative fragment as well as the serovar 3-indicative fragment. The five isolates producing a 3/6 banding pattern contain a type I CPS locus, named K6b, similar to serovar 6, but with differences in the cpxABCD and cpsABC gene sequences and the length of intergenic regions (modF-cpxA, and cpsC-cpsD). The main difference found between the K6 and K6b cps genes is a loss of function of a 113 AA UDP-glycosyltransferase found in type 6b due to the amino acid substitutions in the C-terminal domain of Cps6bA. Additionally, the isolates harbor a LPS O-Ag locus highly identical to those of field and reference strains of serovars 3, 8, 15, 17 and 19 but different from that of serovar 6. Taken together, our results indicate the existence of a subtype of A. pleuropneumoniae, serovar 6, that we called "K6b:O3'', and we propose isolate EH1248 as the reference strain.
我们分析了 15 株胸膜肺炎放线杆菌的荚膜 (CPS) 和脂多糖 O-抗原 (O-Ag) 生物合成基因座，这些菌株包括 11 株北美分离株和 4 株日本分离株，它们对针对血清型 3、6、8 和/或 15 的抗血清有反应。10 株北美分离株扩增出了来自荚膜基因座的血清型 6 指示性片段，而 1 株北美分离株和 4 株日本分离株均扩增出了血清型 6 指示性片段和血清型 3 指示性片段。产生 3/6 带型的 5 个分离株含有一个 I 型 CPS 基因座，命名为 K6b，与血清型 6 相似，但在 cpxABCD 和 cpsABC 基因序列以及基因间区 (modF-cpxA 和 cpsC-cpsD) 的长度上存在差异。在 K6 和 K6b cps 基因之间发现的主要差异是由于 Cps6bA 的 C 末端结构域中的氨基酸取代，导致在 6b 型中发现的一个 113AA UDP-糖基转移酶失去了功能。此外，这些分离株还携带一个 LPS O-Ag 基因座，与血清型 3、8、15、17 和 19 的田间和参考菌株高度相似，但与血清型 6 的不同。总之，我们的研究结果表明存在一种胸膜肺炎放线杆菌血清型 6 的亚型，我们称之为“K6b:O3”，并提议将 EH1248 分离株作为参考菌株。
