alpha-chymotrypsin and Caliciviridae-Infections

Human noroviruses (HuNoVs) are the leading cause of acute gastroenteritis worldwide. Histo-Blood Groups Antigens (HBGAs) have been described as attachment factors, promoting HuNoV infection. However, their role has not yet been elucidated. This study aims to evaluate the ability of HBGAs to protect HuNoVs against various factors naturally found in the human digestive system. The effects of acid pH and proteolytic enzymes (pepsin, trypsin, and chymotrypsin) on GII.4 virus-like particles (VLPs) and GII.4 HuNoVs were studied, both during interactions and non-interaction with HBGAs. The results showed that GII.4 VLPs and GII.4 HuNoVs behaved differently following the treatments. GII.4 VLPs were disrupted at a pH of less than 2.0 and in the presence of proteolytic enzymes (1,500 units/mL pepsin, 100 mg/mL trypsin, and 100 mg/mL chymotrypsin). VLPs were also partially damaged by lower concentrations of trypsin and chymotrypsin (0.1 mg/mL). Conversely, the capsids of GII.4 HuNoVs were not compromised by such treatments, since their genomes were not accessible to RNase. HBGAs were found to offer GII.4 VLPs no protection against an acid pH or proteolytic enzymes.

Topics: Blood Group Antigens; Caliciviridae Infections; Capsid; Chymotrypsin; Dose-Response Relationship, Drug; Gastroenteritis; Humans; Hydrogen-Ion Concentration; Norovirus; Pepsin A; Peptide Hydrolases; Trypsin; Virus Attachment

Calicivirus particles isolated from rabbits suffering from acute RHD were compared with virions found in rabbits with chronic disease. Liver homogenates of rabbits with the protracted disease display no hemagglutinating activity and contain viral particles with diameters of 25-27 nm. These virions contain only one structural protein of 30 kDa and are distinctly smaller than intact rabbit hemorrhagic disease virus (RHDV) (32-40 nm). To prove the RHDV identity of the smaller virions, their reactivity with RHDV specific antibodies was investigated by immunoblots of the virion protein and by immunoelectron microscopy. Proteolytic digestion of RHDV particles with alpha-chymotrypsin did not transform RHDV into the smaller form. We assume that these core-like particles (CLPs) are not a result of proteolytic digestion but arise from a truncated RHDV genome or defective expression.

Topics: Animals; Caliciviridae Infections; Chymotrypsin; Hemorrhagic Disease Virus, Rabbit; Humans; Liver; Microscopy, Immunoelectron; Rabbits; Virion