Transmitted by the fecal–oral or respiratory route, these viruses infect the livers of mice and have been used as an animal disease model for hepatitis.

[8] MHV-1, MHV-2, MHV-3, MHV-A59, MHV-S, MHV-JHM and other virus strains replicate in the respiratory tract and then spread to other organs such as the liver, lungs and brain.

[citation needed] MHV-JHM mainly infects the central nervous system and has been widely studied since 1949.

In rats, these nerve-infecting hepatitis viruses can cause acute or chronic neurological symptoms[11] and stimulate the immunity of mice upon infection.

[citation needed] Infection leads to demyelination, serving as an animal disease model of multiple sclerosis.

MHV-1, MHV-S and MHV-Y are weak viral strains; MHV-2, MHV-3, MHV-A5 9 and MHV-JHM are more virulent, being relatively mild in adult mice but having a high mortality in newborns.

[15] In 2002, American virologist Ralph S. Baric developed a reverse genetic system for mouse hepatitis virus in which a complete MHV cDNA was assembled from smaller fragments.

[16] In fancy rats, the rat coronavirus (RCoV or RCV) consists mainly of two virus strains, sialodacryoadenitis virus (SDAV) and Parker's RCoV (RCoV-P), both of which cause respiratory tract infections, with the former also affecting the eyes, Harderian gland, and salivary glands.

HE can bind to sialic acid on the surface of the host cell and promote viral infection, and has acetyl esterase activity, which can degrade receptors to release the bound virus.

Ribonuclease L in cells activates the defense mechanism for degrading viral RNA[25] and auxiliary protein 5a inhibits host interferon.

[35] When rat hepatitis viruses of different strains infects cells at the same time, template switching can occur while genetic replication is carried out, resulting in gene recombination, which may be important for the evolution of viral diversity.

Some scholars suggest that the common ancestor of this clade may be a mouse virus, which was then transmitted by rats to humans and cattle.

RNA–RNA recombination between different strains of the murine coronavirus was found to occur at a high frequency both in tissue culture[47] and in the mouse central nervous system.

[36] These findings suggest that RNA–RNA recombination may play a significant role in the natural evolution and neuropathogenesis of coronaviruses.

[36] Sialodacryoadenitis virus[48] is a highly infectious coronavirus of laboratory rats that can be transmitted between individuals by direct contact and indirectly by aerosol.

[50] Infection of mice with mouse hepatitis virus has been used as a model system to examine ivermectin as a treatment for coronaviruses.