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A single M protein mutation affects the acid inactivation threshold and growth kinetics of a chimeric flavivirus

Caroline C Maier1, Simon Delagrave, Zhen-xi Zhang

  • 1Virology Department, Acambis Inc., 38 Sidney Street, Cambridge, MA 02139, USA.

Virology
|February 17, 2007
PubMed

Insights

A novel Japanese encephalitis virus mutation in the M protein enhances acid sensitivity and viral growth. This flavivirus M protein modification impacts viral inactivation pH and replication kinetics without affecting neurovirulence.

Area of Science:

  • Virology
  • Molecular Biology
  • Structural Biology

Background:

  • Flaviviridae viruses, including Japanese encephalitis virus (JEV), pose significant global health threats.
  • Understanding flavivirus envelope protein structure and function is crucial for developing antiviral strategies.
  • No prior studies have reported M protein mutations affecting flavivirus acid inactivation pH.

Purpose of the Study:

  • To investigate the impact of a specific M protein mutation on flavivirus particle stability and infectivity.
  • To characterize the in vitro acid sensitivity of a modified Japanese encephalitis-yellow fever chimera (ChimeriVax-JE) virus.
  • To assess the effect of the M protein mutation on viral growth kinetics and in vivo pathogenicity.

Main Methods:

  • Site-directed mutagenesis was used to introduce a proline substitution for glutamine at M5 (MQ5P) in the ChimeriVax-JE virus.
  • In vitro acid sensitivity assays were performed to determine the pH at which virus titer is reduced by 50%.
  • Viral growth kinetics were analyzed in Vero cells, and neurovirulence/neuroinvasiveness were evaluated in a mouse model.

Main Results:

  • The MQ5P mutation significantly increased the acid sensitivity of the chimeric virus by 0.3 pH units (from pH 6.08 to 6.38).
  • Growth kinetics of the MQ5P mutant virus were accelerated in Vero cells compared to the wild-type.
  • Neurovirulence and neuroinvasiveness in mice remained unaffected by the M protein mutation.

Conclusions:

  • The M protein plays a role in modulating flavivirus particle acid stability.
  • The M protein may influence the function of the envelope (E) protein during the viral cell infection cycle.
  • This M protein mutation offers a potential tool for studying flavivirus entry and assembly mechanisms.

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