Effect of Formaldehyde Inactivation on Poliovirus

Inactivated polio vaccines, which have been used in many countries for more than 50 years, are produced by treating live poliovirus (PV) with formaldehyde. However, the molecular mechanisms underlying virus inactivation are not well understood. Infection by PV is initiated by virus binding to specific cell receptors, which results in viral particles undergoing sequential conformational changes that generate altered structural forms (135S and 80S particles) and leads to virus cell entry. We have analyzed the ability of inactivated PV to bind to the human poliovirus receptor (hPVR) using various techniques such as ultracentrifugation, fluorescence-activated cell sorting flow cytometry and real-time reverse transcription-PCR (RT-PCR). The results showed that although retaining the ability to bind to hPVR, inactivated PV bound less efficiently in comparison to live PV. We also found that inactivated PV showed resistance to structural conversion in vitro, as judged by measuring changes in antigenicity, the ability to bind to hPVR, and viral RNA release at high temperature. Furthermore, viral RNA from inactivated PV was shown to be modified, since cDNA yields obtained by RT-PCR amplification were severely reduced and no infectious virus was recovered after RNA transfection into susceptible cells.

 

Source: jvi.asm.org

People have been treating poliovirus with formaldehyde for over 60 years – and it’s only NOW that someone thought to study in detail what happens!

I love this stuff: analytical centrifugation could have been done any time in the last fifty years (and has been, in determining structural transitions) but the newer techniques such as flow cytometry and RT-PCR could not. Analytically determining now what was empirically observed to work when polio vaccines were first made, is a historically important vindication of pioneering work that has almost made the viruses go away.

Simple and obvious findings, essentially – it is obvious that methylene bridging between amino acids would affect structural transitions; so too that HCHO treatment would kill viral ssRNA – but it hadn’t been DONE properly previously.  Great stuff!

See on Scoop.itVirology and Bioinformatics from Virology.ca

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2 Responses to “Effect of Formaldehyde Inactivation on Poliovirus”

  1. AJ Cann Says:

    Quantitatively, I’m guessing it’s the RNA inactivation which has the biggest effect on infectivity.

    • rybicki Says:

      Yes, you are not unacquainted with poliovirus, are you? I imagine the rest of the effects are minimally contributory; knocking out the RNA HAS to be the single biggest factor influencing lack of infectivity. Takes me back to doing similar things with bromoviruses, back there in 1981…B-)

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