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Updated: Aug 19, 2026
Influenza A Virus Studies in a Mouse Model of Infection
Published on: September 7, 2017
Contamination of a specific-pathogen-free rat breeding colony with Human parainfluenzavirus type 3
Hironori Miyata1, Tamotsu Kanazawa2, Kazumoto Shibuya3
1Animal Research Center, University of Occupational and Environmental Health, 1-1 Iseigaoka Yahatanishi, Kitakyushu 807-8555, Japan.
Abstract:
Routine antibody surveillance for Sendai virus in a breeding colony suggested viral invasion into laboratory rats. A more specific haemagglutination-inhibition test implied that the agent was related closely to Human parainfluenza virus type 3 (hPIV3), rather than Sendai virus. To isolate this virus, Vero cells were inoculated with lung homogenates of 30 young animals from the colony. One of the cultures became positive at the second passage by RT-PCR directed to the hPIV3 NP and L genes. Cytopathic effect with cell fusion was observed at the third passage. The HN gene of this virus (KK24) had >93 % similarity to those of other hPIV3 isolates, suggesting a human origin of KK24. Experimental intranasal inoculation of KK24 into SD rats showed virus replication in the lungs at 3-5 days post-infection (p.i.). Pathological examination of the lungs at day 5 p.i. indicated a moderate detachment, degradation and apoptosis of bronchial epitheliocytes with peribronchial mononuclear infiltrations. At day 7 p.i., these changes became less prominent, and no lesions were apparent at day 10 p.i. or later. The infected rats seroconverted at day 7 p.i. On the contrary, none of the 30 experimentally infected ICR mice showed any pathological lesions in their lungs, despite seroconversion at 7 days p.i. These results suggest that hPIV3 can invade rat colonies and has a moderate and transient pathogenicity in rats. This is the first report of non-experimental hPIV3 infection in laboratory rats, unexpectedly detected by antibody screening for Sendai virus.
Insights
Human parainfluenza virus type 3 (hPIV3) unexpectedly invaded a laboratory rat colony. This virus showed moderate, transient pathogenicity in rats but not mice, highlighting a new concern for animal research.
Area of Science:
- Veterinary Virology
- Infectious Diseases
- Laboratory Animal Science
Background:
- Routine antibody surveillance for Sendai virus in a laboratory rat colony indicated a potential viral invasion.
- Further testing revealed the agent was closely related to Human parainfluenza virus type 3 (hPIV3), not Sendai virus.
Purpose of the Study:
- To isolate and characterize the unknown virus detected in the rat colony.
- To determine the pathogenicity of the isolated hPIV3 strain (KK24) in laboratory rats and mice.
Main Methods:
- Vero cells were inoculated with lung homogenates from infected rats.
- Virus isolation was confirmed by RT-PCR targeting hPIV3 genes.
- Experimental intranasal inoculation of rats and mice with the isolated virus (KK24).
- Pathological examination and serological analysis of infected animals.
Main Results:
- A novel hPIV3 strain, KK24, was isolated and confirmed by RT-PCR and cytopathic effects.
- KK24 replicated in rat lungs, causing moderate, transient pathological changes (epithelial cell damage, inflammation) at 3-7 days post-infection.
- Infected rats seroconverted, while experimentally infected mice showed no lung lesions but did seroconvert.
- The HN gene of KK24 showed >93% similarity to known hPIV3 isolates, suggesting a human origin.
Conclusions:
- Human parainfluenza virus type 3 can invade laboratory rat colonies.
- hPIV3 exhibits moderate and transient pathogenicity in rats, with no observed pathology in mice.
- This represents the first report of non-experimental hPIV3 infection in laboratory rats, detected via Sendai virus antibody screening.
