Related Experiment Videos
Interference between influenza A viruses with a cleavable and a noncleavable hemagglutinin; pH-stability after mixed
1Institut für Virologie, Justus-Liebig-University Giessen, Federal Republic of Germany.
Abstract:
The infectivity of influenza A viruses like fowl plague virus (FPV) with a cleaved hemagglutinin (HA) is highly sensitive to treatment at pH 5, while strains like PR 8 or virus N with a noncleaved HA survive under this condition. After double infection of chick embryo cells with FPV and PR 8 or virus N, the yield of virus with the HA gene of FPV is greatly reduced. However, it can now survive treatment at pH 5, and the surviving FPV particles form plaques only in the presence of trypsin, indicating that they were coated by the HA of PR 8 or virus N, depending on the coinfecting virus. The results are discussed with respect to the build-up and maintenance of a large reservoir of nonpathogenic influenza A viruses with noncleavable HA in water fowl.
Insights
Influenza A virus infectivity depends on hemagglutinin (HA) cleavage. Coinfection showed that FPV with cleaved HA acquired noncleaved HA from other viruses, enabling survival at low pH.
Area of Science:
- Virology
- Molecular Biology
- Immunology
Background:
- Influenza A virus infectivity is determined by hemagglutinin (HA) cleavage.
- Cleaved HA is sensitive to low pH, while noncleaved HA confers resistance.
- Fowl plague virus (FPV) possesses cleaved HA, unlike PR 8 or virus N strains.
Purpose of the Study:
- To investigate the effect of coinfection on influenza A virus HA cleavage and infectivity.
- To understand the mechanism of HA exchange between influenza viruses.
- To explore the implications for influenza virus evolution in waterfowl.
Main Methods:
- Double infection of chick embryo cells with FPV and PR 8 or virus N.
- Assessment of virus yield and infectivity after low pH treatment.
- Analysis of HA acquisition through plaque assays in the presence of trypsin.
Main Results:
- Coinfection significantly reduced the yield of FPV with cleaved HA.
- Surviving FPV particles acquired resistance to low pH treatment.
- Evidence of HA exchange, with FPV particles coated by coinfecting virus HA.
Conclusions:
- Influenza A viruses can exchange hemagglutinin genes during coinfection.
- This exchange mechanism allows viruses with cleaved HA to acquire resistance to low pH.
- Findings suggest a role for HA exchange in maintaining nonpathogenic influenza viruses in waterfowl reservoirs.