Universidad Nacional de Colombia, Sede Bogotá. Facultad de Medicina Veterinaria y de Zootecnia. Departamento de Salud Animal, Centro de Investigación en Inmunología e Infectología Veterinaria (CI3V)., Carrera 30 No. 45-03, Bogotá, CP 11001, Colombia.
BMC Vet Res. 2021 Apr 8;17(1):150. doi: 10.1186/s12917-021-02862-5.
PCV3 is a member of the Circovirus family, associated with disease and mortality in pigs. It is not clear whether PCV3 putatively causes clinical symptoms and disease. In the present case, we reported a gilt infected with PCV3 associated with reproductive failures, vertical transmission, tissue lesions, viral replication by in situ hybridization, and the hypothesis that some strains of PCV3 clade one are associated with reproductive failures at the field level.
In May 2019, a pig farm in Colombia reported increased reproductive failures, and the presence of PCV3 in gilts and sows was established in a single form or coinfections, mainly with PCV2 and PPV7. Ten sows with a single infection with PCV3 were found, and one gilt with a pre-farrowing serum viral load above 10 was studied. This gilt was followed up during the pre-farrowing, farrowing period and on her litter for 6 weeks. During dystocic farrowing, a mummy and ten piglets were released, including two weak-born piglets. The highest viral loads for PCV3 were found in the mummy and the placenta. In the weak-born piglets, there were viral loads both in serum and in tissues, mainly in the mesenteric ganglia and lung. Replication of PCV3 in these tissues was demonstrated by in situ hybridizations. PCV3 was also found in the precolostrum sera of piglets and colostrum, showing vertical transmission. The viral load in piglets decreased gradually until week six of life. The viral genome's complete sequencing was made from the mummy, and its analysis classified it as PCV3 clade one.
This report confirms that PCV3 can cause disease at the field level, and putatively, in this case, we find the generation of reproductive failures. The ability of PCV3 to cause disease as a putative pathogen may be associated with the viral load present in the pig and the strain that is affecting the farm. For this case, we found that viral loads above 10 (4.93 log genomic copies / mL) in the gilt were associated with clinical manifestation and that some PCV3 strains belonging to clade one are more associated with the reproductive presentation.
PCV3 是圆环病毒科的一个成员，与猪的疾病和死亡有关。目前尚不清楚 PCV3 是否会导致临床症状和疾病。在本病例中，我们报告了一例感染 PCV3 的后备母猪，其表现为繁殖障碍、垂直传播、组织损伤、原位杂交检测到病毒复制，并提出某些 PCV3 1 型毒株与田间水平的繁殖障碍有关。
2019 年 5 月，哥伦比亚的一个养猪场报告繁殖障碍增加，并在后备母猪和母猪中检测到 PCV3 单一感染或混合感染，主要与 PCV2 和 PPV7 混合感染。发现 10 头母猪和 1 头后备母猪呈单一 PCV3 感染，其中 1 头产前血清病毒载量超过 10 的后备母猪进行了研究。该后备母猪在产前、分娩期及其仔猪 6 周内进行了跟踪。在难产分娩过程中，有木乃伊和 10 头仔猪被释放，其中包括 2 头弱仔。在木乃伊和胎盘中检测到最高的 PCV3 病毒载量。在弱仔中，血清和组织中均检测到病毒载量，主要在肠系膜神经节和肺组织中。通过原位杂交证实了这些组织中 PCV3 的复制。还在仔猪的初乳前血清和初乳中发现了 PCV3，表明存在垂直传播。仔猪的病毒载量逐渐下降，直到出生后 6 周。从木乃伊中提取了病毒基因组的完整序列，并进行了分析，将其分类为 PCV3 1 型。
本报告证实 PCV3 可以在田间水平引起疾病，并且在本例中，我们发现了繁殖障碍的发生。PCV3 作为一种潜在病原体引起疾病的能力可能与猪体内的病毒载量和影响农场的毒株有关。对于本病例，我们发现后备母猪的病毒载量超过 10（4.93 log 基因组拷贝/毫升）与临床表现有关，属于 1 型的某些 PCV3 株与繁殖表现更为相关。
