Mousepox (infectious ectromelia): past, present, and future

Area of Science:

• Veterinary Virology
• Infectious Diseases
• Rodent Health

Background:

• Mousepox is a significant orthopoxvirus infection affecting laboratory mice, first identified in England in 1930.
• The virus has historically been enzootic in mouse populations across Europe, Japan, and China, posing a continuous threat to research settings.
• Despite not being native to North America or Australia, mousepox has been introduced, leading to severe outbreaks (epizootics).

Observation:

• Mousepox presents a spectrum of clinical signs dependent on mouse genotype, ranging from acute hepatitis with high mortality to inapparent infections.
• The virus can contaminate or replace other viruses during mouse passage and spread through intact mice, tumors, or tissues.
• Transmission between mouse stocks highlights the challenges in maintaining disease-free research animal populations.

Findings:

• Mousepox infection severity is highly variable, influenced by the host mouse's genetic makeup.
• The virus demonstrates a capacity for horizontal transmission within and between mouse colonies through various biological materials.
• Vaccinia virus vaccination has proven effective in protecting mice and controlling mousepox outbreaks.

Implications:

• Effective control strategies for mousepox include vaccination with vaccinia virus and, in severe cases, depopulation and sterilization of infected facilities.
• Understanding mouse genotype-specific susceptibility is crucial for managing and preventing mousepox outbreaks in research settings.
• Preventing the introduction and spread of mousepox is vital for maintaining the integrity of biomedical research reliant on healthy mouse models.