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Human-avian influenza virus reassortants: effect of reassortment pattern on multi-cycle reproduction in MDCK cells
N V Kaverin1, I A Rudneva, Y A Smirnov
1D. I. Ivanovsky Institute of Virology, Academy of Medical Sciences, Moscow, U.S.S.R.
Abstract:
Human-avian influenza reassortants possessing the HA gene of the avian parent virus were tested for their ability to replicate in MDCK cells at 37 degrees C and 31 degrees C. Both avian parent viruses, A/Duck/Ukraine/1/63 (H3N8) and A/Duck/Hoshimin/014/78 (H5N3) induced an efficient multi-cycle infection at 37 degrees C, but replicated poorly at 31 degrees C, whereas the human parent virus, MDCK-adapted variant of A/USSR/90/77 (H1N1) strain, replicated efficiently at both temperatures. The reassortant clone possessing the HA gene of A/Duck/Ukraine/1/63 virus and the other 7 genes of A/USSR/90/77 virus replicated at both temperatures almost as efficiently as the human parent virus. Among the reassortants between A/Duck/Hoshimin/014/78 and A/USSR/90/77, the clones possessing the HA and NA genes of the avian strain, or the HA, NA, NP, and NS genes of the avian strain, and the other genes of the human parent virus, replicated poorly at both temperatures, especially at 31 degrees C, whereas the reassortant possessing the HA, NA, and M genes of the avian virus replicated at both temperatures fairly efficiently. The results are discussed in connection with the limitations imposed by different genes upon avian influenza viruses' ability to replicate in mammalian cells.
Insights
Avian influenza viruses show limited replication in mammalian cells, but reassortants with specific avian genes can adapt. Gene composition significantly impacts replication efficiency at different temperatures.
Area of Science:
- Virology
- Molecular Biology
- Genetics
Background:
- Influenza A viruses are classified by surface proteins Hemagglutinin (HA) and Neuraminidase (NA).
- Human-avian influenza reassortants are crucial for studying viral adaptation and pandemic potential.
- Understanding gene-specific replication is key to predicting viral behavior in new hosts.
Purpose of the Study:
- To investigate the replication capabilities of human-avian influenza reassortant viruses in mammalian cells.
- To determine the influence of specific avian influenza genes on viral replication at different temperatures (37°C and 31°C).
- To identify genetic factors limiting or enabling avian influenza virus replication in mammalian hosts.
Main Methods:
- Generation of human-avian influenza reassortant viruses by genetic exchange.
- In vitro replication assays in Madin-Darby Canine Kidney (MDCK) cells at 37°C and 31°C.
- Analysis of viral replication efficiency based on plaque assays and viral titers.
Main Results:
- Avian parent viruses replicated efficiently at 37°C but poorly at 31°C, while the human parent virus replicated well at both temperatures.
- Reassortants with the HA gene from A/Duck/Ukraine/1/63 (H3N8) and other genes from A/USSR/90/77 (H1N1) showed efficient replication at both temperatures.
- Reassortants with multiple avian genes (HA, NA, NP, NS) showed poor replication, whereas those with avian HA, NA, and M genes demonstrated moderate replication.
Conclusions:
- The HA gene plays a significant role in the temperature-dependent replication of avian influenza viruses in mammalian cells.
- Specific combinations of avian and human influenza genes influence replication efficiency and temperature adaptation.
- Genetic reassortment can confer partial or significant replication ability in mammalian cells, highlighting the complex interplay of viral genes.