# State of the art in biosafety at the European National Reference Laboratories for Transmissible Spongiform Encephalopathies

## TL;DR

This paper reviews biosafety practices in European labs handling prions to reduce the risk of occupational exposure to transmissible spongiform encephalopathies.

## Contribution

The study identifies gaps in biosafety procedures across labs and proposes actions to improve consistency and safety.

## Key findings

- Most labs adhere to TSE-specific biosafety guidelines, but procedures vary significantly.
- Fewer labs have protocols for pathology and immunohistochemistry compared to ELISA and western blot assays.
- The EURL-TSE has created a digital repository and initiated regular meetings to improve biosafety practices.

## Abstract

Laboratory technicians handling material containing or potentially infected with prions are exposed to the occupational risk of contracting infectious forms of Creutzfeldt–Jakob disease. The occurrence of three fatalities among laboratory personnel with a history of occupational exposure to bovine spongiform encephalopathy has highlighted the need for greater attention to the correct implementation of biosafety procedures in laboratories that handle prions.

The European Reference Laboratory for Transmissible Spongiform Encephalopathies (EURL-TSE) carried out a survey to review biosafety procedures currently adopted by the 31 National Reference Laboratories for TSEs (NRLs), stimulate discussion among laboratory directors, and define future actions aimed at reducing the risk of occupational exposure among laboratory personnel.

The survey showed that 83.9% of laboratories adhered to TSE-specific biosafety guidelines, and 61.3% had conducted a biosafety risk assessment, while the biosafety level of the facilities had been determined in 93.5% of cases. In addition, 83.9% reported implementing staff biosafety training protocols, and 77.4% had procedures addressing the risk associated with sharp or pointed tools. Most laboratories had established biosafety procedures for ELISA and western blot assays, whereas fewer had protocols for pathology and immunohistochemistry. Among the three facilities performing experimental inoculations, only two indicated having specific biosafety measures in place.

Despite the overall positive results, the survey showed that biosafety procedures are applied heterogeneously across the NRLs. The EURL-TSE will further encourage the full implementation of specific biosafety procedures to address the gaps identified by the survey. The EURL-TSE has created a digital repository of guidelines and bibliographical sources on the subject. It also initiated biannual virtual meetings to discuss critical issues emerged from the survey and to encourage the mutual exchange of experiences and good practices between NRLs Directors.