HEV Vaccine Development

HEV Vaccine Development

Hepatitis E virus (HEV) infection is a global disease and the leading cause of acute viral hepatitis, with approximately 20 million cases per year. HEV infection is prevalent in approximately one-third of the world's population and causes a wide range of clinical manifestations, ranging from acute hepatitis to fatal liver failure, with a mortality rate of approximately 0.5%, but as high as 25% in pregnant women.

Overview of HEV Infection

HEV, the only member of the hepatitis virus family, has significant heterogeneity and can infect many animals, such as bats, deer, wild boars, pigs, rats, rabbits, etc., with two different epidemiological patterns. HEV, which is mainly transmitted through polluted water in developing countries, can cause many extrahepatic diseases, such as extensive neurological syndrome, in addition to serious liver disease.

HEV-induced hepatitis has been a public health problem in developing and developed countries since the confirmation of HEV zoonosis. At the same time, the broad host range of zoonotic HEV suggests the existence of multiple transmission routes that may lead to human infection. Unfortunately, compared to other liver viruses such as hepatitis B virus and hepatitis C virus, HEV is still relatively unknown to the public, and our understanding of HEV is extremely limited.

HEV Genome

HEV is a quasi-enveloped, single-stranded positive-sense RNA virus that belongs to the Hepadnaviridae. The genome of HEV is about 7.3 kb in length and contains three open reading frames (ORFs). ORF1 encodes a nonstructural protein responsible for viral RNA replication, ORF2 encodes a capsid protein, and ORF3 encodes a small protein involved in virion morphogenesis and release. HEV virions are 27-32 nm in size and are produced by the assembly of ORF2-encoded capsid proteins. The capsid protein contains epitopes recognized by virus-neutralizing antibodies and is therefore the basis of all recombinant vaccines.

HEV genome. (Liu X, et al., 2021)

Types of HEV

HEV can infect a variety of mammalian species, including humans, and over time, has evolved into 4 genotypes, genotypes 1 and 2 infect humans and often lead to epidemic outbreaks through the fecal-oral route, while genetic Types 3 and 4 are zoonotic. The four genotypes share a common epitope that elicits predominantly neutralizing antibodies, manifesting as a single serotype in humans.

HEV VLP Vaccine

In recent years, there has been an increase in reported cases of HEV infection in developing countries, and vaccination is an effective way to prevent HEV infection and control HEV transmission. However, the lack of a reliable cell culture method to culture HEV makes the development of HEV inactivated or live attenuated vaccines impractical. Structurally mimicking natural virions, but without a viral genome, virus like particles (VLPs) are well recognized by the immune system and are highly immunogenic due to their size and repetitive arrangement of B-cell epitopes displayed on the particle surface. Therefore, HEV VLPs generally exhibit sufficient antigenicity and immunogenicity for vaccine development.

How We Can Help

As an expert in building VLPs from VLPlant^TM platform, CD BioSciences uses its expertise to help our clients develop HEV vaccines. We are good at customizing our services according to the needs of our clients. Please contact us if you are interested.

Our capabilities include but are not limited to:

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Reference

1. Liu X.; et al. Cellular Organelles Involved in Hepatitis E Virus Infection. Pathogens. 2021, 10:1206 -1219.