On the entry of an emerging arbovirus into host cells: Mayaro virus takes the highway to the cytoplasm through fusion with early endosomes and caveolae-derived vesicles.
On the entry of an emerging arbovirus into host cells: Mayaro virus takes the highway to the cytoplasm through fusion with early endosomes and caveolae-derived vesicles.
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作者：
Carvalho CAM;Silva JL;Oliveira AC;Gomes AMO
马亚罗病毒(Mayaro Virus，MAYV)是一种发生在南美洲的突发性甲型病毒，与一种类似基孔肯雅的人类发热性疾病的零星暴发有关，并伴有严重的关节痛。尽管MAYV在城市出现的潜力很大，但它仍然是一种鲜为人知的病毒，关于其感染周期的信息很少，包括相应的早期事件。即使对于典型的甲型病毒，细胞进入机制仍然有一些粗糙的边缘需要修剪：尽管笼蛋白介导的内吞作用被认为是假定的途径，但像通过细胞膜直接注射病毒基因组这样截然不同的替代途径似乎是可能的。我们的目的是澄清MAYV进入宿主细胞所利用的进入途径的关键细节。通过荧光显微镜追踪病毒与Vero细胞表面的第一次接触，我们发现病毒通过快速的内吞过程进入，并依赖于与酸性内体隔间的融合。此外，根据空斑分析的评估，阻断笼状蛋白介导的内吞作用或耗尽细胞膜上的胆固醇会导致对病毒感染的强烈抑制。根据这一线索，我们发现早期的内小体和小凹来源的囊泡都是MAYV融合的靶膜。我们的发现揭开了导致MAYV生产性感染的最初事件，并阐明了合理抗病毒治疗的潜在靶点，此外还提供了对甲型病毒进入细胞的途径的更好理解。
Mayaro virus (MAYV) is an emergent sylvatic alphavirus in South America, related to sporadic outbreaks of a chikungunya-like human febrile illness accompanied by severe arthralgia. Despite its high potential for urban emergence, MAYV is still an obscure virus with scarce information about its infection cycle, including the corresponding early events. Even for prototypical alphaviruses, the cell entry mechanism still has some rough edges to trim: although clathrin-mediated endocytosis is quoted as the putative route, alternative paths as distinct as direct virus genome injection through the cell plasma membrane seems to be possible. Our aim was to clarify crucial details on the entry route exploited by MAYV to gain access into the host cell. Tracking the virus since its first contact with the surface of Vero cells by fluorescence microscopy, we show that its entry occurs by a fast endocytic process and relies on fusion with acidic endosomal compartments. Moreover, blocking clathrin-mediated endocytosis or depleting cholesterol from the cell membrane leads to a strong inhibition of viral infection, as assessed by plaque assays. Following this clue, we found that early endosomes and caveolae-derived vesicles are both implicated as target membranes for MAYV fusion. Our findings unravel the very first events that culminate in a productive infection by MAYV and shed light on potential targets for a rational antiviral therapy, besides providing a better comprehension of the entry routes exploited by alphaviruses to get into the cell.