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Human Norovirus Vaccine Development

Most outbreaks and sporadic cases of acute gastroenteritis (AGE) in developing countries are caused by infection with human norovirus (HuNoV), an enterovirus spread primarily through fecal-contaminated water. Norovirus infection can cause debilitating illness such as nausea, vomiting, and more. These symptoms can be prolonged in vulnerable populations and cause significant health and economic burdens. However, there are currently no specific or effective treatments and vaccines against HuNoV infection.

3D illustration of human norovirus.

Overview of HuNoV

Noroviruses (NoV) are highly infectious agents responsible for the majority of nonbacterial gastroenteritis cases in humans, causing over 95% of epidemic viral gastroenteritis in adults. They commonly lead to outbreaks in various social environments such as restaurants, schools, nursing homes, and cruise ships. High-risk groups include young children, the elderly, military personnel, and immunocompromised individuals.

Genome of HuNoV

The HuNoV, part of the classified genus Norovirus, belongs to the Caliciviridae family. This virus is small, icosahedral, and has a positive-sense single-stranded RNA genome. The RNA genome measures approximately 7.5 kb nucleotides and contains three open reading frames (ORFs). ORF1 is responsible for encoding six nonstructural proteins crucial for viral replication: namely, the N-terminal protein (p48), nucleoside-triphosphatase (NTPase), 3A-like protein (p22), genome-linked viral protein (VPg), protease (Pro), and RNA-dependent polymerase (RdRp or Pol). ORF2 encodes the major capsid protein (VP1), which includes the shell (S) domain and protruding (P1 and P2) subdomains. Meanwhile, ORF3 encodes a minor structural protein (VP2), which plays a role in the encapsidation of viral RNA and stabilization of the VP1 protein. Both the genomic and subgenomic RNAs are covalently attached to a viral protein called VPg at their 5ʹ ends and have a polyadenylated tail at their 3ʹ ends.

Genome organization of HuNoV. Genome of human norovirus (HuNoV). (Sion E.; et al., 2023)

Noroviruses exhibit significant genetic diversity, with a classification system identifying 49 genotypes among 10 genogroups (GI—GX) based on the major capsid protein's amino acid sequences. However, only a few genogroups—including GI, GII, and GIV—are responsible for acute gastroenteritis in humans, referred to as human norovirus (HuNoV). Among these, the GII.4 genogroup is currently predominant in viral gastroenteritis outbreaks worldwide.

Expression Systems for HuNoV VLPs

Expression Vector	Assembly Method	Expression System	Result
E. coli	Gene cloning	Cold-shock expression system	The self-assembled Norovirus VLPs were morphologically identical to native virions and demonstrate a similar binding pattern to the VLPs assembled in other cell types that have been tested.
Recombinant baculovirus vector	cDNA subcloning	Cell-free systems	The capsid proteins resembled those of native Norwalk virus and self-assembled.
Recombinant vesicular stomatitis virus (VSV) plasmid vector	Restriction enzyme cloning	Baculovirus expression system	The capsid protein expressed by VSV was able to form HuNoV VLPs, whose morphology and antigenicity were similar to those of natural virus particles.
Venezuelan equine encephalitis virus (VEE) replicon plasmid vector	Overlapping extension PCR	Mammalian system	Transfection resulted in the expression of high concentrations of rNV capsid proteins, which self-assembled into NV VLPs.
Recombinant Baculovirus (Bac-to-Bac system)	Capsid gene subcloning	Baculovirus expression in insect cells (H5)	High-yield expression of Norwalk-like virus capsid protein was achieved.
pcDNA3.1(+) vecto	Whole Genome Cloning	Mammalian system	The expressed HuNoV VP1 protein was consistent with the expected size.
Bacmid	VLP gene cloning	Expression in insect and mammalian cells	Different expression systems for consensus sequences of prevalent GII.4 variants displayed structurally similar VLPs.

How We Can Help

CD BioSciences specializes in the production and engineering of VLPs. Utilizing our VLPlant^TM platform, we are dedicated to supporting our clients in their research on HuNoV and the development of HuNoV vaccines.For partnership opportunities or to learn more about our cutting-edge capabilities,, please feel free to contact us.

Quote and Ordering

Ordering process.

Reference

Sion E.; et al., Trends on Human Norovirus Virus-like Particles (HuNoV-VLPs) and Strategies for the Construction of Infectious Viral Clones toward In Vitro Replication. Life. 2023; 13(7):1447.

Human Norovirus Vaccine Development