Noroviruses, Sapoviruses, and Astroviruses

Noroviruses: Evolutionary Dynamics, Epidemiology, Pathogenesis, and Vaccine Advances—A Comprehensive Review

“…The generation of point mutations in the norovirus RNA genome has been widely observed during long-term norovirus infection in both immunocompetent hosts [27][28][29][30] and immunocompromised individuals [12,[31][32][33]. Like the other RNA viruses, the lack of proofreading repair mechanisms associated with the RNA replicates and transcriptase activity remains the critical factor driving the accumulation of point mutations [34].…”

“…The commonest food vehicles for viral transmission are fresh or frozen soft fruits and vegetables, undercooked or raw seafood, and ready-to-eat foods, including salads and sandwiches, which, though they require handling, involve little or no further cooking [24]. In several norovirus outbreak investigations, foods such as leafy vegetables, raspberries, fruits, and shellfish which were irrigated with or grown in water that was contaminated with faeces and then eaten raw were implicated in the disease transmission [12,[63][64][65][66][67]. Bivalve molluscs such as mussels, scallops, cockles, clams, and oysters accumulate multiple norovirus strains in their edible tissues via filter feeding [38,68], presenting opportunities for infectious human norovirus inter-and intragenotype co-infection and subsequent viral genomic recombination within the host [69].…”

“…Epidemiologically, seroprevalence studies have suggested that human exposures to norovirus occur frequently, with worldwide anti-norovirus antibody prevalence rates approaching >80% by adulthood. Nevertheless, adults repeatedly display a high degree of susceptibility to noroviruses when challenged naturally and experimen-tally [12]. In several early human challenge studies, some norovirus-infected volunteers were found to show susceptibility to reinfection by both the homotypic and heterologous strains [133][134][135].…”

“…HilleVax has announced the completion of enrolment of over 3000 subjects in six countries (Columbia, United States, Mexico, Dominican Republic, Panama, and Peru) for the Norovirus Efficacy and Safety Trial for Infants (NEST-IN1) in 2024 (http://www.hillevax.com/ accessed on 2 February 2024). Together, the available VLP-based norovirus vaccines have shown great promise [64,159,[163][164][165][167][168][169][170][171][172][173][174][175][176] (Table 1), but concerns remain about the following: (1) the efficacy in the community against commonly circulating and genetically heterogenous viruses whose pandemic strains are easily replaced within short time intervals [12]. This factor may necessitate frequent vaccine reformulations in response to evolution as it is currently in place for influenza viruses.…”

“…Noroviruses are genetically diverse groups of emerging RNA viruses, which continue to evolve in humans through both point mutations and genome recombination [11]. Of note, variations in the amino acid sequences of viral proteins associated with genomic mutations have resulted in an increased period of virus-shedding [12], evasion of pre-existing immunity associated with past infections [13], and reduced virus clearance in patients infected with heterologous strains [14]. Currently, ten genogroups (GI-GX) comprising 60 distinct P-types and 49 capsid genotypes have been reported in association with human and animal infection worldwide [15].…”