NON-FATAL INFECTION OF MICE FOLLOWING INTRACEREBRAL INOCULATION OF YELLOW FEVER VIRUS

Area of Science:

• Virology
• Immunology
• Infectious Diseases

Background:

• Yellow fever virus (YFV) can cause fatal neurotropic infections in mice.
• Previous observations suggested the possibility of non-fatal YFV infections.

Purpose of the Study:

• To investigate the occurrence and characteristics of non-fatal and inapparent yellow fever virus infections in mice.
• To determine factors influencing non-fatal YFV infections, including virus dose and substrain.
• To assess the impact of non-fatal infections on infectivity titrations.

Main Methods:

• Intracerebral inoculation of mice with various YFV strains and substrains.
• Monitoring for clinical signs of infection and survival rates.
• Exclusion of other infectious agents through isolation attempts.
• Serological detection of YFV antibodies.
• Assessment of resistance to subsequent challenge with neurotropic YFV.

Main Results:

• Non-fatal and inapparent YFV infections were observed in mice.
• Infection outcome (fatal vs. non-fatal) was dependent on YFV dose and substrain; smaller doses and specific substrains (e.g., 17DD low, 17D(3)) yielded more non-fatal outcomes.
• Non-fatal infections increased infectivity titers by up to 25% when included in calculations.
• Jungle YFV strains showed a higher incidence of non-fatal infections compared to 17D substrains.

Conclusions:

• Non-fatal and inapparent YFV infections occur in mice and are influenced by virus dose and substrain.
• Accurate quantification of YFV infectivity requires accounting for non-fatal infections.
• The characterization of YFV strains can be enhanced by assessing the incidence of non-fatal infections.