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Viremia induced by influenza virus
I Mori1, T Komatsu, K Takeuchi
1Department of Microbiology, Fukui Medical School, Japan.
Abstract:
A mouse model of influenza A/PR/8 virus infection was adopted to investigate the blood and various tissues of intranasally infected mice for the presence of viral RNA by using the nested polymerase chain reaction. The nucleoprotein gene was detected in the red blood cell fraction from 1 to 5 days post-inoculation, while it was found in the lung and brain up to 14 days and in the liver, spleen, kidney, heart, and skeletal muscle up to 7 days. The virus-specific messenger RNA was transiently found in these organs. When mice received the uv-inactivated virus, viremia did not occur. The prior transfer of the hyperimmune serum prevented pneumonia but not bronchitis, and viremia was totally abolished. These results suggest: (1) viremia occurs during the acute phase of infection, (2) the virus is present in various organs and there the virus gene is transiently expressed, and (3) the virus enters the blood stream possibly through capillaries of the infected alveolar wall. Viremia may influence the pathogenesis of influenza.
Insights
Influenza A virus RNA was detected in mouse blood and tissues, including lungs and brain, for up to 14 days. Viremia during acute infection may impact influenza pathogenesis.
Area of Science:
- Virology
- Immunology
- Pathogenesis
Background:
- Influenza A virus is a significant human pathogen.
- Understanding viral dissemination and host response is crucial for developing effective treatments.
Purpose of the Study:
- To investigate the presence and distribution of influenza A virus RNA in blood and various tissues of infected mice.
- To explore the role of viremia in influenza pathogenesis.
Main Methods:
- Utilized a mouse model of intranasal influenza A/PR/8 virus infection.
- Employed nested polymerase chain reaction (PCR) to detect viral RNA in blood and tissue samples.
- Administered uv-inactivated virus and hyperimmune serum to assess their effects on viral dissemination and disease.
Main Results:
- Viral RNA was detected in red blood cells from 1-5 days post-inoculation.
- Viral RNA persisted in lungs and brain up to 14 days, and in liver, spleen, kidney, heart, and skeletal muscle up to 7 days.
- Virus-specific messenger RNA expression was transient in these organs; uv-inactivated virus did not cause viremia, and hyperimmune serum prevented pneumonia but not bronchitis.
Conclusions:
- Viremia occurs during the acute phase of influenza infection.
- The influenza virus disseminates to various organs, with transient gene expression.
- Viremia may play a role in the pathogenesis of influenza, potentially originating from infected alveolar capillaries.