Male Germ Cells Support Long-Term Propagation of Zika Virus

Evidence of male-to-female sexual transmission of Zika virus (ZIKV) and viral RNA in semen and sperm months after infection support a potential role for testicular cells in ZIKV propagation. Here, we demonstrate that germ cells (GC) are most susceptible to ZIKV. We find that only GC infected by ZIKV, but not those infected by dengue fever (DENV) and yellow fever virus (YFV), produce high levels of infectious virus. This observation coincides with decreased expression of interferon-stimulated gene Ifi44l in ZIKV-infected GC and over-expression of Ifi44l results in reduced ZIKV production. Using primary human testicular tissue, we demonstrate that human GC are also permissive for ZIKV infection and production. Finally, we identify berberine chloride as a potent inhibitor of ZIKV infection in both murine and human testes. Together, these studies identify a potential cellular source for propagation of ZIKV in testes and a candidate drug for preventing sexual transmission of ZIKV. RNA-seq was used to compare the gene expression profiles in mock-infected GC with those infected with ZIKV, DENV, and YFV. Among the top 150 most-upregulated genes in DENV- (> 10-fold) or YFV-infected GC (> 4-fold), we selected genes that were upregulated in both DENV- and YFV-infected GC but not in ZIKV-infected GC.

寨卡病毒（Zika virus, ZIKV）可经男性向女性的性途径传播，且感染数月后仍可在精液与精子中检测到病毒RNA的相关证据，提示睾丸细胞可能参与寨卡病毒的增殖过程。本研究证实，生殖细胞（germ cells, GC）对寨卡病毒最为易感。我们发现，仅被寨卡病毒感染的生殖细胞可产生高滴度的感染性病毒颗粒，而被登革热病毒（dengue fever, DENV）与黄热病毒（yellow fever virus, YFV）感染的生殖细胞则无此现象。该现象与寨卡病毒感染的生殖细胞中干扰素刺激基因（interferon-stimulated gene）Ifi44l的表达下调相吻合，且过表达Ifi44l可减少寨卡病毒的增殖。利用原代人睾丸组织实验，我们证实人类生殖细胞同样支持寨卡病毒的感染与增殖。最后，我们发现氯化小檗碱（berberine chloride）可在小鼠与人类睾丸组织中有效抑制寨卡病毒的感染。综上，本研究明确了睾丸内寨卡病毒增殖的潜在细胞来源，同时筛选出可用于阻断寨卡病毒性传播的候选药物。本研究采用RNA测序（RNA-seq）技术，对比了模拟感染、寨卡病毒、登革热病毒及黄热病毒感染的生殖细胞的基因表达谱。在登革热病毒感染（上调倍数>10）或黄热病毒感染（上调倍数>4）的生殖细胞中排名前150的上调基因中，我们筛选出仅在登革热病毒与黄热病毒感染的生殖细胞中上调，而在寨卡病毒感染的生殖细胞中未出现上调的基因。