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Updated: Jul 16, 2026
Influenza A Virus Studies in a Mouse Model of Infection
Published on: September 7, 2017
Gender influences infectivity in C57BL/6 mice exposed to mouse minute virus
Marvin L Thomas1, Brent C Morse, James O'Malley
1National Institutes of Health, Bethesda, MD, USA. mt98h@nih.gov
Abstract:
Two natural outbreaks of mouse minute virus (MMV) are described. Observations during management of the naturally infected colonies led to a study in which 4-wk-old C57BL/6NCr and C57BL/6Tac mice were inoculated oronasally with an immunosuppressive variant of MMV (MMVi), as were adult C57BL/6NCr lactating dams or their pups (age, 10 d). By day 28 postinoculation, 100% of the 4-wk-old male C57BL/6NCr and C57BL/6Tac mice, 56.2% of 4-wk-old C57BL/6NCr female and 62.5% of 4-wk-old C57BL/6Tac female mice, 100% of adult lactating C57BL/6NCr dams, and 100% of inoculated pups (10 d) had seroconverted. Serologically positive nursing dams did not infect their nursing pups. In contrast, when nursing pups were inoculated, 100% of their dams seroconverted by 28 d postinoculation. Only 1 of 4 facility sentinels (Tac:SW female mice) seroconverted to MMVi and none of the 4 research sentinels (Tac:SW female mice) seroconverted under a once-weekly bedding transfer program. Consequently, 4 new research Tac:SW sentinels of each gender (n = 8) were placed in known-positive cages at cage-change; 100% of the male mice but 0% of the females seroconverted by day 48. Study results suggest gender influences both infectivity and the ability to detect subclinical infections of MMVi. Other factors that may influence detection of MMV include mouse strain or stock, short shedding period, and prolonged time between cage changes. In light of the data from both the natural infections and the experimental cases, cessation of breeding likely will be beneficial when trying to eradicate this virus.
Insights
Mouse minute virus (MMV) outbreaks reveal gender influences MMV infectivity and detection. Eradicating MMV may require stopping breeding in infected mouse colonies.
Area of Science:
- Veterinary Virology
- Laboratory Animal Science
- Immunology
Background:
- Mouse minute virus (MMV) is an immunosuppressive parvovirus affecting laboratory mice.
- Natural outbreaks necessitate understanding MMV transmission dynamics and detection challenges.
- Previous studies highlight MMV's impact on research colonies, but transmission routes and influencing factors require further elucidation.
Purpose of the Study:
- To investigate the infectivity and seroconversion rates of an immunosuppressive MMV variant (MMVi) in different mouse strains, ages, and genders.
- To evaluate the efficacy of sentinel mice in detecting MMVi under standard husbandry practices.
- To identify factors influencing MMV transmission and detection, informing eradication strategies.
Main Methods:
- Oronasal inoculation of C57BL/6 mice (4-wk-old males and females, lactating dams, and 10-d-old pups) with MMVi.
- Serological monitoring (seroconversion) at 28 and 48 days post-inoculation.
- Assessment of sentinel mouse program effectiveness using Tac:SW mice under different exposure scenarios.
Main Results:
- High seroconversion rates observed across inoculated groups, with variations based on age, sex, and inoculation route.
- Male mice exhibited higher susceptibility and seroconversion rates than females.
- Sentinel mice showed limited MMVi detection, particularly females, suggesting potential underestimation of virus presence.
- Nursing dams did not transmit MMV to pups, but inoculated pups infected dams.
Conclusions:
- Gender significantly influences MMVi infectivity and the ability to detect subclinical infections.
- Mouse strain, short shedding periods, and infrequent cage changes can impact MMV detection.
- Cessation of breeding is a recommended strategy for eradicating MMV from infected colonies.
