Table_1_A genetic and virulence characterization of Brazilian strains of Mycoplasma hyopneumoniae.docx

Mycoplasma hyopneumoniae (M. hyopneumoniae) is considered the primary causative agent of porcine enzootic pneumonia (EP), a chronic contagious respiratory disease that causes economic losses. Obtaining new pathogenic isolates and studying the genome and virulence factors are necessary. This study performed a complete sequencing analysis of two Brazilian strains, UFV01 and UFV02, aiming to characterize the isolates in terms of the virulence factors and sequence type. The complete genome analysis revealed the main virulence genes (mhp385, mhp271, MHP_RS03455, p102, p97, p216, MHP_RS00555, mhp107) and ST-123, the presence of three toxin-related genes (tlyC, PLDc_2 and hcnC), and some genetic groups specific to these two isolates. Subsequently, the pathogenicity of the isolates was evaluated via an experimental infection conducted in a swine model. The study was divided into three groups, namely a negative control group (n = 4) and two test groups (n = 8), totaling 20 animals. They were challenged at 35 days of age with 107 CCU (Color Changing Units) M. hyopneumoniae via the intratracheal route. The UFV01 group showed earlier and higher seroconversion (IgG) (100%), while only 50% of the UFV02 group seroconverted. The same trend was observed when analyzing the presence of IgA in the bronchoalveolar lavage fluid (BALF) at 35 days post-infection (dpi). The UFV01 group had a mean macroscopic lesion score of 11.75% at 35 dpi, while UFV02 had 3.125%. Microscopic lesions were more severe in the UFV01 group. Based on laryngeal swab samples evaluated by qPCR, and the detection began at 14 days. The UFV01 group showed 75% positivity at 14 dpi. The UFV02 group also started excreting at 14 dpi, with a positivity rate of 37.5%. The results indicate that the UFV01 isolate exhibits higher virulence than UFV02. These findings may aid in developing new vaccines and diagnostic kits and establishing experimental models for testing.

支原体肺炎（M. hyopneumoniae）被认为是猪流行性肺炎（EP）的主要致病因素，该病为一种慢性传染性呼吸道疾病，导致经济损失。获取新的病原分离株并研究其基因组及致病性因素至关重要。本研究对巴西的两个菌株，UFV01和UFV02，进行了完整的测序分析，旨在从致病性因素和序列类型两个方面对分离株进行特征化。完整的基因组分析揭示了主要的致病基因（mhp385、mhp271、MHP_RS03455、p102、p97、p216、MHP_RS00555、mhp107）和ST-123，存在三个与毒素相关的基因（tlyC、PLDc_2和hcnC），以及特定于这两个分离株的一些遗传群。随后，通过在猪模型中进行的实验感染评估了分离株的致病性。研究分为三组，即一个阴性对照组（n=4）和两个试验组（n=8），总计20只动物。它们在35日龄时通过气管内途径接受107 CCU（颜色变化单位）的M. hyopneumoniae的挑战。UFV01组表现出更早和更高的血清转换率（IgG）（100%），而UFV02组仅有50%发生血清转换。在感染后35天（dpi）分析支气管肺泡灌洗液（BALF）中IgA的存在时，也观察到了相同的趋势。在35 dpi时，UFV01组的平均肉眼病变评分为11.75%，而UFV02组为3.125%。UFV01组的显微镜下病变更为严重。基于喉拭子样本的qPCR评估，检测始于14 dpi。UFV01组在14 dpi时显示出75%的阳性率。UFV02组也始于14 dpi开始排泄，阳性率为37.5%。结果表明，UFV01分离株的致病性高于UFV02。这些发现可能有助于开发新的疫苗和诊断试剂盒，并建立实验模型以进行测试。