Picobirnavirus: A Putative Emerging Threat to Humans and Animals

Diarrheal diseases remain fatal threat to human and animal population with the emergence of new types of pathogens. Among them, viral gastroenteritis plays a lion share with a number ranging over 100 different types including emerging and re-emerging types of viruses. Recent viral metagenomics studies confirm the co-existence of viruses in gastrointestinal tract of several different host species. A Picobirnavirus, consisting of 2 segments, has recently attained attention due to its wide host range and genetic variability. Until 2011, these small viruses were not considered as a separate virus family, when a new family (Picobirnaviridae) was approved by the International Committee on Taxonomy of Viruses (ICTV). Currently two distinct genogroups (GG-I and GG-II) and one predicted genogroup (GG-III) are included in the Picobirnaviridae family. Recently, picobirnavirus infections have been reported from almost all species including wild animals where persistent infection of the virus is also reported. Picobirnaviruses (PBVs) are also reported as opportunistic pathogens in immuno compromised hosts including HIV infected patients. Presence of atypical picobirnaviruses with shorter genomic segments along with genetic closeness of animal and human PBVs and its ability to infect immuno-compromised hosts pose a heavy threat for all human and animal. Currently RNA dependent RNA polymerase based RT-PCR detection is considered as a rapid and sensitive method for detection of PBV. SYBR based real time PCR, RNA PAGE analysis, electron microscopy also serve as detection methods for PBVs. Unavailability of permissive cell lines or animal models remain hurdles for studying the different molecular mechanisms for viral entry, disease causation or even the mode of persistence in reservoir hosts.