The Interaction between Nidovirales and Autophagy Components

Abstract

Autophagy is a conserved intracellular catabolic pathway that allows cells to maintain homeostasis through the degradation of deleterious components via specialized double-membrane vesicles called autophagosomes. During the past decades, it has been revealed that numerous pathogens, including viruses, usurp autophagy in order to promote their propagation. Nidovirales are an order of enveloped viruses with large single-stranded positive RNA genomes. Four virus families (Arterividae, Coronaviridae, Mesoniviridae, and Roniviridae) are part of this order, which comprises several human and animal pathogens of medical and veterinary importance. In host cells, Nidovirales induce membrane rearrangements including autophagosome formation. The relevance and putative mechanism of autophagy usurpation, however, remain largely elusive. Here, we review the current knowledge about the possible interplay between Nidovirales and autophagy.

Inhibition of Cytosolic Phospholipase A2α Impairs an Early Step of Coronavirus Replication in Cell Culture

“…It remains to be studied whether (and to what extent) Cer contribute to autophagy and apoptosis in coronavirus-infected cells. Both processes have been suggested to be involved in coronavirus replication and represent emerging fields of coronavirus research, with partially controversial information being reported for different viral and cellular systems (22,27,28,(69)(70)(71)(72)(73)(74)(75).…”

“…The cells were washed with PBS, fixed with 3% formaldehyde and 1% glutaraldehyde in 0.1 M PBS, and postfixed in 1% osmium tetroxide. After incubation in 1% aqueous uranyl acetate (Polysciences), specimens were dehydrated in an ethanol series (30,50,70,80,90,96, and 100% [vol/vol], 20 min each) and embedded in Epon (Serva). From the heat-cured blocks, silver-to-gold ultrathin sections were cut and subsequently treated for contrast in uranyl acetate and lead citrate.…”

The ER stress sensor IRE1 and MAP kinase ERK modulate autophagy induction in cells infected with coronavirus infectious bronchitis virus

“…Although not essential for coronavirus replication, autophagy is undoubtedly activated during the infection with different coronaviruses including TGEV, MHV, IBV and other viruses belonging to the order Nidovirales (Cong et al, 2017). Notably, overexpression of the nonstructural protein 6 (nsp6) of IBV, MHV, and SARS-CoV was shown to induce the formation of autophagosomes in the transfected cells (Cottam et al, 2011).…”

Insight into the evolution of nidovirus endoribonuclease based on the finding that nsp15 from porcine Deltacoronavirus functions as a dimer

“…Nidoviruses are positive-sense, single-stranded, and enveloped RNA viruses with genome sizes ranging from ϳ12.7 to 31.7 kb; these viruses include the families of Coronaviridae, Arteriviridae, Roniviridae, and Mesoniviridae (1)(2)(3). Nidoviruses are found in a broad range of hosts.…”

“…They have similar genomic organizations in which the two largest overlapping open reading frames (ORF1a and ORF1b) are located within the 5Ј-proximal two-thirds of the genome, and a ribosomal frame-shifting event is involved in the translation process (13,14). The viral RNA can be translated into 12 or 13 nonstructural proteins (nsps) 3 in arteriviruses and 16 nsps in most coronaviruses to exert different biological functions, such as the formation of double-membrane vesicles (DMVs) and replication-transcription complex (RTCs) formation (3,15,16). Viral RNA synthesis has been observed in DMVs of SARS-CoV and MHV (15,17).…”