Serological investigation of lentiviruses of small ruminants in the microregions of Alto Médio Canindé, Picos and Floriano, Piauí state, Brazil

ABSTRACT: Small ruminant lentiviruses (LV) is the generic term for the caprine arthritis-encephalitis and Maedi-Visna viruses, which belong to the Retroviridae family, Orthoretrovirinae subfamily, Lentivirus genus. The virus infects goats and sheep, causing slow course of disease with inflammatory, chronic and degenerative lesions, which can reach several organs, provoking cachexia and death. Infected animals eliminate the virus mainly through secretions and excretions and transmit it especially in close contact situations. There is no treatment to date. The control is based on segregated creation, management and sacrifice of the positive. This infectious agent has been reported in various parts of the world and is responsible for significant economic losses. It was verified in several states of Brazil and there are seroepidemiological data in southeast and southwest mesoregions of Piauí, Brazil. This research aimed to perform serological survey to investigate the occurrence of antibodies to LV in sheep and goats, in the regions of Alto Médio Canindé, Picos and Floriano. So, 1,280 and 1,360 serum goats and sheep samples, respectively, were collected, coming from 20 municipalities, distributed in the 3 microregions. The number of samples was proportional to the actual herd of each municipality. The samples were analyzed using the agar gel immunodiffusion test. None of the surveyed sera reacted positively, though there is a null seroprevalence. It was emphasized the importance of implementing a rigorous control program in order to prevent the introduction and spread of this infectious agent in these microregions.

摘要：小反刍动物慢病毒（Small ruminant lentiviruses, LV）是山羊关节炎脑炎病毒与梅迪-维斯纳病毒的统称，隶属于反转录病毒科（Retroviridae）、正反转录病毒亚科（Orthoretrovirinae）、慢病毒属（Lentivirus）。该病毒可感染山羊与绵羊，引发病程缓慢的炎症性、慢性退行性病变，可累及多个脏器，最终导致恶病质与死亡。感染动物主要通过分泌物与排泄物排出病毒，尤其在密切接触场景下发生传播。目前尚无有效治疗手段。该病的防控主要依托阳性个体的隔离饲养、管控与扑杀措施。目前全球多个地区均有该传染性病原的报道，其可造成严重的经济损失。巴西多个州已证实该病毒的存在，且在巴西皮奥伊州（Piauí）的东南部与西南部中区域已有血清流行病学相关数据。本研究旨在针对上中卡尼迪（Alto Médio Canindé）、皮科斯（Picos）以及弗洛里亚诺（Floriano）三个区域开展血清学调查，以探究绵羊与山羊体内针对小反刍动物慢病毒的抗体阳性情况。本研究共采集来自上述3个微区域内20个市镇的山羊血清样本1280份、绵羊血清样本1360份，样本数量与各市镇的实际畜群规模成正比。所有样本均采用琼脂凝胶免疫扩散试验进行检测。本次调查的血清样本均未呈现阳性反应，血清阳性率为零。本研究强调，需在上述微区域内推行严格的防控方案，以阻止该传染性病原的传入与扩散。