Proteolytic enhancement of rotavirus infectivity: molecular mechanisms

Abstract

The polypeptide compositions of single-shelled and double-shelled simian rotavirus particles were modified by exposure to proteolytic enzymes. Specificially, a major outer capsid polypeptide (VP3) having a molecular weight of 88,000 in double-shelled particles was cleaved by trypsin to yield two polypeptides, VP5* and VP8* (molecular weights, 60,000 and 28,000, respectively). The cleavage of VP3 by enzymes that enhanced infectivity (trypsin, elastase, and pancreatin) yielded different products compared to those detected when VP3 was cleaved by chymotrypsin, which did not enhance infectivity. The appearance of VP5* was correlated with an enhancement of infectivity. Cleavages of the major internal capsid polypeptide VP2 were also observed. The VP2 cleavage products had molecular weights similar to those ofknown structural and nonstructural rotavirus polypeptides. We confirmed the precursor-product relationships by comparing the peptide maps of the polypeptides generated by digestions with V-8 protease and chymotrypsin. The remaining rotavirus structural polypeptides, including the outer capsid glycoproteins (VP7 and 7a), were not altered by exposure to pancreatic enzymes. Cleavage of VP3 was not required for virus assembly, and specific cleavage of the polypeptides occurred only on assembled particles. We also discuss the role of cleavage activation in other virus-specific biological functions (e.g., hemagglutination and virulence).

Unique physicochemical properties of human enteric Ad41 responsible for its survival and replication in the gastrointestinal tract

“…Data on the entry and infection mechanism of enteric viruses are scarce. It was observed that the proteolytic cleavage, believed to occur in the lumen of intestine, enhances rotavirus infectivity in vitro (Estes et al, 1981). In addition, observations on membrane permeabilization by rotaviruses led to the hypothesis of a direct virus penetration across the plasma membrane lipid phase (Ruiz et al, 1994).…”

Understanding the penetrance of intrinsic protein disorder in rotavirus proteome

“…Four conserved cysteine residues; i.e., Cys203, Cys216, Cys318, and Cys380, are present in all the rotavirus strains [70]. Trypsin cleavage at Arg241 and Arg247 yields the receptor binding VP8* fragment and VP5* fragment, that enhances the viral infectivity [70][71][72]. The 265-474 region of VP5* possesses membrane permeabilization property and is highly disordered as predicted by all individual predictors {Fig.…”

Immature and Mature Human Astrovirus: Structure, Conformational Changes, and Similarities to Hepatitis E Virus

“…Proteolytic cleavage is a common mechanism for activation of both enveloped and nonenveloped viruses, including influenza virus, 15,16 coronavirus, 17 rotavirus, 18 reovirus, 19 and alphaviruses. 20 A recurring theme is that cleavage triggers a conformational change in a surface spike or other cell-attachment domain.…”