Recombinant Norovirus GII VP1 (Full length) [His]

Norovirus was first isolated in the feces of patients with acute gastroenteritis in Norwalk and became known as Norwalk virus, and since then virus particles with similar morphology but slightly different antigens have been isolated from the feces of other patients with acute gastroenteritis, and these viral particles have been unanimously named norovirus (NoV). NoV is a single-stranded positive-stranded RNA virus with no envelope and a genome consisting of three open reading frames (ORFs), ORF1, ORF2, and ORF3. ORF1 encodes a large multimeric nonstructural protein (NS), which is later split into six parts by proteases. ORF2 encodes the NoV capsid protein VP1, which contains a conserved shell S domain and a prominent P domain. The P domain is involved in the interaction between the virus and the receptor cell. ORF3 encodes the VP2 protein, a minor structural protein of NoV, which is involved in VP1 formation and viral assembly and maintains capsid protein stability. According to the NoV VP1 gene, the virus can be categorized into 10 gene groups and more than 50 genotypes, among which GI and GII gene group infections are the most common. Patients infected with the GII gene group account for about 70% of NoV-infected patients.

Figure 1. NoV genome organisation and translated proteins
(Source: Winder N, et al. 2022)

NoV infection is characterized by seasonal prevalence, with incidence higher in winter. Low infectious dose, easy mutation, high environmental resistance, rapid transmission, high infectiousness, long detoxification time, and short immune protection time lead to widespread susceptibility of NoV in people of all ages. The virus is capable of infecting humans in a number of ways, including contaminated food and water, and human-to-human contact. Thus, NoV infections can occur in epidemiologic outbreaks as well as epidemics, and the source of infection is both symptomatic and asymptomatic infections, as well as healthy carriers.

The incubation period of NoV infection is 12-48h, with a rapid onset and short course. A proportion of patients have no obvious symptoms of infection, and a proportion of patients present with symptoms of gastrointestinal disease, which may be accompanied by agranulocytosis. Acute gastroenteritis caused by NoV usually lasts 2-3 days and is typically self-limiting. In contrast, in immunocompromised individuals NoV chronic infection can persist for weeks or years, thus making the patient increasingly weaker and thus life-threatening. In addition, NoV infection can also lead to intestinal stress syndrome, necrotizing small bowel colitis, and can cause viral encephalopathy.

NoV GII VP1