Wiesner et al.
Susceptibility of tick-borne encephalitis virus to inactivation by heat, acidic pH, chemicals, or UV treatment
J. Infect. Dis. 2021, 223:714-718. doi:10.1093/infdis/jiaa405

Due to its potential to cause severe disease, handling of TBE virus needs special containment laboratories categorized as biosafety level 3 (BSL 3). In many institutions, a limited number of approved (and validated) inactivation protocols exist for the safe processing and removal of TBE virus-containing samples.

A variety of different inactivation procedures were evaluated for their ability to reduce TBE virus titers and to inactivate infectious viral particles.

  • Heat treatment can effectively inactivate TBE virus. Within 5 minutes at ≥55°C, viral titers can be reduced by more than 4 logs (also in samples containing 50% serum).
  • Incubation of TBE virus in medium containing 2% fetal bovine serum in an open tube under UV light (254 nm wavelength) for 10 minutes had no effect on the infectivity of the virus, while an irradiation time of 30 to 60 minutes reduced the titers by 3.3 to 3.6 logs. This inactivation effectivity was reduced when volumes larger than 200 µl volumes were tested.
  • When various alcohols were assessed in concentrations of 10% to 50%, it could be shown that isopropanol at 20% was much more effective compared to ethanol or methanol, but with increasing concentration the latter alcohols could also effectively inactivate TBE virus.
  • Common detergents (SDS, Triton X-100, Tween-20, sodium deoxycholate) were also tested. TBE virus was most susceptible to inactivation by SDS even at 0.04% concentration, while Triton X-100 can effectively inactivate TBE virus at 0.2% concentration, but virus treated with Tween-20 remained infectious.

The authors have shown that TBE virus can safely be inactivated using a variety of procedures that minimally interfere with downstream analyses commonly used in research laboratories. It should be noted, however, that the efficacy of virus inactivation may depend on sample volume and composition, and therefore in-house validation of protocols is needed for chosen inactivation procedures.

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