Coronavirus envelope protein: current knowledge

Abstract

Background Coronaviruses (CoVs) primarily cause enzootic infections in birds and mammals but, in the last few decades, have shown to be capable of infecting humans as well. The outbreak of severe acute respiratory syndrome (SARS) in 2003 and, more recently, Middle-East respiratory syndrome (MERS) has demonstrated the lethality of CoVs when they cross the species barrier and infect humans. A renewed interest in coronaviral research has led to the discovery of several novel human CoVs and since then much progress has been made in understanding the CoV life cycle. The CoV envelope (E) protein is a small, integral membrane protein involved in several aspects of the virus’ life cycle, such as assembly, budding, envelope formation, and pathogenesis. Recent studies have expanded on its structural motifs and topology, its functions as an ion-channelling viroporin, and its interactions with both other CoV proteins and host cell proteins. Main body This review aims to establish the current knowledge on CoV E by highlighting the recent progress that has been made and comparing it to previous knowledge. It also compares E to other viral proteins of a similar nature to speculate the relevance of these new findings. Good progress has been made but much still remains unknown and this review has identified some gaps in the current knowledge and made suggestions for consideration in future research. Conclusions The most progress has been made on SARS-CoV E, highlighting specific structural requirements for its functions in the CoV life cycle as well as mechanisms behind its pathogenesis. Data shows that E is involved in critical aspects of the viral life cycle and that CoVs lacking E make promising vaccine candidates. The high mortality rate of certain CoVs, along with their ease of transmission, underpins the need for more research into CoV molecular biology which can aid in the production of effective anti-coronaviral agents for both human CoVs and enzootic CoVs.

Potential inhibitors against 2019-nCoV coronavirus M protease from clinically approved medicines

“…Among all known RNA viruses, coronaviruses have the largest genomes, ranging from 26 kb to 32 kb in length (Regenmortel et al, 2000;Schoeman and Fielding, 2019). Besides encoding structural proteins, majority part of the coronavirus genome is transcribed and translated into a polypeptide, which encodes proteins essential for viral replication and gene expression (Lai and Holmes, 2001).…”

Structural, glycosylation and antigenic variation between 2019 novel coronavirus (2019-nCoV) and SARS coronavirus (SARS-CoV)

“…The infection of coronavirus is initiated via the interaction of viral envelope with host cellular membrane [11]. The internalization of virus also depends upon the potential glycosylation sites present on viral glycoprotein.…”

Identification of potential cross-protective epitope between a new type of coronavirus (2019-nCoV) and severe acute respiratory syndrome virus

“…Coronaviruses (CoVs) are single-stranded RNA viruses which belong to order Nidovirales, family Coronaviridae, subfamily Coronavirinae (Schoeman and Fielding, 2019) and have been classified into four major groups: α-CoVs，β-CoVs, γ-CoVs and δ-CoVs with 17 subtypes (Saminathan et al, 2014). CoVs primarily infect wild animals including mammals and birds.…”

“…They also infect humans and cause various diseases such as upper and lower respiratory tract infections, and respiratory syndromes. Among them, Severe Acute Respiratory Syndrome (SARS)-CoV and Middle Eastern Respiratory Syndrome (MERS)-CoV can cause serious respiratory syndrome in human (Schoeman and Fielding, 2019). For instance, the outbreak of SARS in 2003 led to a pandemic with 8906 infected cases and 774 deaths reported worldwide (WHO, 2003).…”

“…The coronaviral genome normally encodes four structural proteins including spike (S) protein, nucleocapsid (N) protein, membrane (M2) protein and envelope (E) protein (Schoeman and Fielding, 2019). S protein contains the receptor-binding domain (RBD), and mediates the attachment of viruses to the surface receptors in host cells, as well as the subsequent fusion between the viral and host cell membranes to facilitate viral entry into host cells (Kirchdoerfer et al, 2016).…”