Murine coronavirus

Murine coronavirus (M-CoV), also known as Mouse Hepatitis Virus (MHV), is a member of the Coronaviridae family and Betacoronavirus genus. It is a highly contagious virus that primarily affects the liver, central nervous system, and respiratory system of mice, leading to a range of diseases from mild to fatal. The study of M-CoV has provided valuable insights into the pathogenesis, immune response, and mechanisms of virus-induced demyelination, serving as a model for human coronaviruses, including severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV).

Etiology

Murine coronavirus is an enveloped, positive-sense, single-stranded RNA virus. Its genome encodes for four main structural proteins: the spike (S) protein, envelope (E) protein, membrane (M) protein, and nucleocapsid (N) protein. The S protein facilitates viral entry into host cells by binding to specific receptors on the cell surface, a critical step in the viral life cycle.

Pathogenesis

After M-CoV enters the host cell, it replicates in the cytoplasm, leading to cell death and inflammation. The virus can infect various cell types in mice, including hepatocytes, neurons, and epithelial cells, causing a wide range of symptoms. In the liver, it can lead to hepatitis, while in the central nervous system, it can cause encephalitis and demyelination, similar to the pathology observed in multiple sclerosis in humans. The respiratory form of the disease is characterized by interstitial pneumonia.

Immune Response

The immune response to M-CoV infection involves both the innate and adaptive immune systems. Initially, infected cells release interferons and other cytokines to limit virus spread and activate immune cells. Subsequently, the adaptive immune response, including both B and T lymphocytes, is essential for virus clearance. However, the immune response can also contribute to disease pathology, such as demyelination in the central nervous system.

Epidemiology

Murine coronavirus is widespread in laboratory and wild mouse populations around the world. Transmission occurs via the fecal-oral route, direct contact, and aerosols, facilitating rapid spread within colonies. The virus can cause outbreaks in laboratory mouse colonies, significantly impacting biomedical research.

Prevention and Control

Preventive measures include the use of specific pathogen-free (SPF) mouse colonies, rigorous biosecurity protocols, and regular surveillance to detect and eliminate the virus. In the event of an outbreak, infected animals are quarantined and culled to prevent further spread.

Research and Implications for Human Health

Research on murine coronavirus has provided insights into coronavirus biology, pathogenesis, and immunity that are relevant to human coronaviruses. It has been a valuable model for studying viral-induced demyelination and testing antiviral drugs and vaccines, contributing to our understanding and management of human coronavirus infections.