Evidence of Infection with Simian Type D Retrovirus in Persons Occupationally Exposed to Nonhuman Primates

Simian type D retrovirus (SRV) is enzootic in many populations of Asian monkeys of the genus Macaca and is associated with immunodeficiency diseases. However, the zoonotic potential of this agent has not been well defined. Screening for antibodies to SRV was performed as part of an ongoing study looking for evidence of infection with simian retroviruses among persons occupationally exposed to nonhuman primates (NHPs). Of 231 persons tested, 2 (0.9%) were found to be strongly seropositive, showing reactivity against multiple SRV antigens representing gag, pol, and env gene products by Western immunoblotting. Persistent long-standing seropositivity, as well as neutralizing antibody specific to SRV type 2, was documented in one individual (subject 1), while waning antibody with eventual seroreversion was observed in a second (subject 2). Repeated attempts to detect SRV by isolation in tissue culture and by using sensitive PCR assays for amplification of two SRV gene regions (gag and pol) were negative. Both individuals remain apparently healthy. We were also unable to transmit this seropositivity to an SRV-negative macaque by using inoculation of whole blood from subject 1. The results of this study provide evidence that occupational exposure to NHPs may increase the risk of infection with SRV and underscore the importance of both occupational safety practices and efforts to eliminate this virus from established macaque colonies.

D型猴逆转录病毒（SRV）在猕猴属（Macaca）的多种亚洲猴种群中呈地方性流行，且与免疫缺陷疾病相关。不过，该病原体的人畜共患病潜力尚未得到明确界定。针对SRV抗体的筛查作为一项正在进行的研究的一部分，旨在排查职业性接触非人灵长类动物（NHPs）的人群中猴逆转录病毒的感染证据。在231名受检者中，有2人（占0.9%）呈强血清学阳性，经免疫印迹试验（Western immunoblotting）检测，其可与SRV的多种抗原发生反应，这些抗原对应gag、pol及env基因的编码产物。其中1名受试者（受试者1）呈现持续长期的血清学阳性，且可检测到针对2型SRV的特异性中和抗体；另1名受试者（受试者2）则出现抗体滴度逐渐衰减，最终转为血清转阴。通过组织培养分离法，以及针对SRV的gag和pol两个基因区域的高灵敏度聚合酶链反应（PCR）扩增检测，反复尝试均未检出SRV。两名受试者目前均无明显健康异常。此外，我们尝试使用受试者1的全血进行接种，无法将该血清学阳性状态传递给SRV阴性的猕猴。本研究结果证实，职业性接触非人灵长类动物可能会增加SRV感染风险，同时强调了职业安全操作规范，以及从已建立的猕猴饲养种群中根除该病毒的工作的重要性。