Noroviruses
Norovirus infections are a major cause of gastroenteritis, and outbreaks occur frequently as causal factors at around .20 million cases of acute gastroenteritis annually, with over 70,000 hospitalizations in addition to other pathogens like rotavirus and also E.Coli. Several factors are currently increasing the challenge posed by norovirus infections to global health with #sarscov2
While vaccines against norovirus diseases have been shown to be of high significance, the development of a broadly effective norovirus vaccine remains difficult, owing to the wide genetic and antigenic diversity of noroviruses with multiple co-circulated variants of various genotypes. In addition, the absence of a robust cell culture system, an efficient animal model, and reliable immune markers of norovirus protection for vaccine evaluation.
The genus Norovirus belongs to the family Caliciviridae and contains the Norwalk virus; this species is divided into at least 10 genogroups, which are further subdivided into at least 48 genotypes with genogroups GI, GII and GIV are known to infect humans.
Human noroviruses have a non-segmented positive- strand RNA genome, of approximately 7.5 kb, that contains three ORFs (Fig. 1). These ORFs encode a large non-structural polyprotein (ORF1), the major structural protein VP1 (ORF2) and the minor structural protein VP2 (ORF3)
In acute infection it is know that both a B and T cell response is needed. Both CD4 and CD8 T cells have also been shown to be required for efficient clearance of primary acute MNoV infection from the intestine and intestinal lymph nodes
Adoptive transfer of either polyclonal anti-MNoV serum or neutralizing anti-MNoV monoclonal antibodies is sufficient to reduce MNoV infection both systemically and in the intestine.
