由胞内劳森菌引起的增生性肠病是养猪业的重要经济相关疾病,但对中国猪场细胞内乳杆菌流行的认识有限。此外,来自中国的胞内乳杆菌分离株没有完整的基因组序列。在这项研究中,我们开发了一种TaqManqPCR,用于通过靶向细菌16SrDNA基因筛选细胞内乳杆菌。实验室评估显示对检测胞内乳杆菌核酸具有良好的敏感性和特异性。使用此方法,我们调查了47个农场中看似健康的猪的891个粪便样本。结果显示样本的筛查阳性率为37.3%(95%CI,34.1-40.5%),农场筛查阳性率为93.6%(95%CI,65.3-94.4%)。群体水平的筛查阳性率为6.67%(95%CI,0.2-31.9%)至40%(95%CI,38-79.6%),而在动物层面,筛查阳性率最高的是12周龄猪[85.7%(95%CI,67.3-96.0%)].对705例有症状猪的腹泻或血性粪便的调查显示,替代母猪的阳性率最高,为37.18%(95%CI,45.1-89.5%)。其次,我们通过PacBio测序对来自中国的胞内乳杆菌PPE-GX01-2022进行了全基因组测序。PPE-GX01-2022的基因组由长度为1,439,110bp的染色体和193,063,39,799和27,067bp的三个质粒组成,分别。这个基因组编码了1,428个预测的蛋白质,44个tRNA,和6个rRNA。序列比较表明,PPE-GX01-2022的基因组序列与美国两个分离株的基因组序列高度同源,这三个分离株共有1378个核心基因。筛查结果表明,中国猪场的胞内乳杆菌患病率很高。此外,中国分离株的基因组序列与美国田间分离株的基因组序列高度同源。
Proliferative enteropathy caused by Lawsonia intracellularis is an important economic associated disease to pig industry, but the knowledge about the prevalence of L. intracellularis in pig farms in China is limited. In addition, there is no complete genome sequence available for L. intracellularis isolates from China. In this study, we developed a TaqMan qPCR for the screening of L. intracellularis by targeting the bacterial 16S rDNA gene. Laboratory evaluations revealed a good sensitivity and specificity on detecting L. intracellularis nucleic acid. Using this method, we investigated 891 fecal samples from apparently healthy pigs in 47 farms. The results demonstrated a screening positive rate of 37.3% (95% CI, 34.1-40.5%) for the samples, and a farm screening positive rate of 93.6% (95% CI, 65.3-94.4%). The screening positive rate at herd level ranged from 6.67% (95% CI, 0.2-31.9%) to 40% (95% CI, 38-79.6%), while at animal level, the highest screening positive rate was found in 12-week-old pigs [85.7% (95% CI, 67.3-96.0%)]. Investigation of 705 diarrheal or bloody feces from symptomatic pigs revealed that the highest positive rate was found in replacement gilts which was 37.18% (95% CI, 45.1-89.5%). Secondly, we conducted the complete genome sequence of a L. intracellularis PPE-GX01-2022 from China through PacBio sequencing. The genome of PPE-GX01-2022 consisted of a chromosome of 1,439,110 bp in length and three plasmids of 193,063, 39,799, and 27,067 bp, respectively. This genome encoded 1,428 predicted proteins, 44 tRNAs, and 6 rRNAs. Sequence comparisons demonstrated that the genome sequence of PPE-GX01-2022 was highly homologous to those of two isolates from US, and these three isolates shared 1,378 core genes. The screening results suggest a high prevalence rate of L. intracellularis in Chinese pig farms. In addition, the genome sequence of the Chinese isolate was highly homologous to those of the field isolates from the US.