Emerging Role of Exosomal Secretory Pathway in Human Tumour Virus Pathogenesis

Viruses are well known for their ability to hijack and manipulate the host cellular machinery to ensure immune evasion, viral survival and pathogenesis. Most animal viruses exhibit exclusive tropism and thus, infect only specific target cells. However, reports on the existence of virions and viral components in non-target cells suggest alternative mechanisms of viral spread. Studies on microvesicles and exosomes promise to provide justification for the presence of viruses at unrelated cell types. Exosomes have attracted the attention of not only cell biologists but also virologists as these vesicles can transport and deliver bioactive information (RNA, proteins, microRNA etc. including virus specific components from infected cells) to unrelated cell types and have the potential to regulate target cell function. Recent studies suggest that viruses can manipulate and hijack the exosome biogenesis and secretory pathway to manipulate the host microenvironment, evade immune response and increase viral accessibility. Here, we review the existing literature on viral interference and exploitation of exosome secretory mechanisms and correlate it with the increased virulence and spread of viruses in the host. Further, we discuss the prospects of exosomes as emerging biomarkers for virus induced pathology, potential of exosomes as delivery vehicles and also the new perspective to viral mediated pathogenesis.