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Arrest of Daudi cell growth by inactive influenza virus in-vitro
Abstract:
We investigated the destructive capability of three influenza A strains, Victoria, PR8, and their recombinant X47, against the human lymphoma cell line Daudi. Both Victoria and X47 strains share the same envelope glycoproteins (H3N2), while PR8, the second parental strain of X47, differs in its envelope glycoproteins (HON1). The H3N2 strains and particularly the X47 recombinant were cytotoxic to Daudi cells while the HON1 strain was not. To reduce the virulence of the oncolytic viruses, we inactivated them either with heat (56 degrees C/45 min) or with formalin. Both treatments significantly reduced the infectivity of the viruses. The X47 virus treated with formalin retained its hemagglutinin (HA) and neuraminidase (NA) activities but lost its cytotoxic potential. On the other hand, the heat-treated X47 virus retained its HA activity, lost its NA activity, but preserved its cytotoxic potential. Thus, the heat-inactivated X47 virus (X56) was the most effective non-virulent oncolytic agent we tested. The X56 virus arrested Daudi cell multiplication in-vitro by inhibiting cellular DNA synthesis. The mechanism by which X56 inhibited Daudi cell DNA synthesis was not related to interferon induction in Daudi cells, and did not necessarily involve the activation of the Epstein-Barr virus (EBV) genome present in Daudi cells. Although the mechanism remains unclear, the oncolytic potential of the X56 virus on Daudi cells was demonstrated.
Insights
Heat-inactivated influenza A virus X56 effectively targets lymphoma cells by inhibiting DNA synthesis. This non-virulent oncolytic agent shows potential for cancer therapy, though its precise mechanism requires further investigation.
Area of Science:
- Virology
- Oncology
- Molecular Biology
Background:
- Influenza A virus strains exhibit varying cytotoxic effects on human lymphoma cells.
- Oncolytic viruses are being explored as a cancer therapy strategy.
- Modifying virus virulence is crucial for developing safe and effective oncolytic agents.
Purpose of the Study:
- To evaluate the oncolytic potential of different influenza A virus strains against the Daudi human lymphoma cell line.
- To investigate the impact of heat and formalin inactivation on virus infectivity and cytotoxicity.
- To identify a non-virulent oncolytic influenza A virus for potential therapeutic applications.
Main Methods:
- In vitro cytotoxicity assays using influenza A strains (Victoria, PR8, X47) against Daudi cells.
- Virus inactivation using heat (56°C/45 min) and formalin.
- Assessment of viral hemagglutinin (HA) and neuraminidase (NA) activity post-inactivation.
- Analysis of Daudi cell proliferation and DNA synthesis inhibition by the inactivated X47 virus (X56).
- Investigation of potential mechanisms including interferon induction and Epstein-Barr virus (EBV) activation.
Main Results:
- Influenza A strains H3N2 (Victoria, X47) were cytotoxic to Daudi cells, while HON1 (PR8) was not.
- Heat-inactivated X47 (X56) retained cytotoxicity and HA activity but lost NA activity.
- Formalin-inactivated X47 lost cytotoxicity but retained HA and NA activity.
- X56 significantly inhibited Daudi cell multiplication by arresting DNA synthesis.
- The mechanism of DNA synthesis inhibition did not involve interferon induction or EBV activation.
Conclusions:
- Heat-inactivated influenza A virus X56 is a potent, non-virulent oncolytic agent against Daudi lymphoma cells.
- X56 exerts its oncolytic effect by inhibiting cellular DNA synthesis.
- Further research is needed to elucidate the exact molecular mechanism of X56-mediated oncolysis.