Understanding how different surfaces and environmental biofilms found in food processing plants affect the spread of COVID-19.

Meat processing plants have been at the center of the SARS-CoV-2 pandemic, with a recent report citing 90% of US facilities having multiple outbreaks during 2020 and 2021. We explored the potential for biofilms to act as a reservoir in protecting, harboring, and dispersing SARS-CoV-2 throughout the meat processing facility environment. To do this, we used Murine Hepatitis Virus (MHV), as a surrogate for SARS-CoV-2, and meat processing facility drain samples to develop mixed-species biofilms on materials found in meat processing facilities (stainless steel (SS), PVC, and ceramic tiles). After exposure to the biofilm organisms for five days post-inoculation at 7°C we conducted quantitative PCR (qPCR) and plaque assays to determine whether MHV could remain both detectable and viable. Our data provides evidence that coronaviruses can remain viable on all the surfaces tested and are also able to integrate within an environmental biofilm. Although a portion of MHV was able to remain infectious after incubation with the environmental biofilm, a large reduction in plaque numbers was identified when compared with the viral inoculum incubated without biofilm on all test surfaces, which ranged from 6.45-9.27-fold higher. Interestingly, we observed a 2-fold increase in the virus-environmental biofilm biovolume when compared to biofilm without virus, indicating that the biofilm bacteria both detected and reacted to the virus. These results indicate a complex virus-environmental biofilm interaction. Although we observed better survival of MHV on a variety of surfaces commonly found in meat processing plants alone than with the biofilm, there is the potential for biofilms to protect virions from disinfecting agents, which has implications for the potential of SARS-CoV-2 prevalence within the meat processing plant environment. Also given the highly infectious nature of SARS-CoV-2, particularly for some of the variant strains such as omicron, having even a residual level of virus present represents a serious health hazard. The increase in biofilm biovolume in response to virus is also a concern for food safety due to the potential of the same being seen with organisms associated with food poisoning and food spoilage.

Murine Hepatitis Virus, a Biosafety Level 2 Model for SARS-CoV-2, Can Remain Viable on Meat and Meat Packaging Materials for at Least 48 Hours.

In 2020 and 2021, many meat processing plants faced temporary closures due to outbreaks of COVID-19 cases among the workers. There are several factors that could potentially contribute to the increased numbers of COVID-19 cases in meat processing plants: the survival of viable SARS-CoV-2 on meat and meat packaging materials, difficulties in maintaining workplace physical distancing, personal hygiene, and crowded living and transportation conditions. In this study, we used murine hepatitis virus (MHV) as a biosafety level 2 (BSL2) surrogate for SARS-CoV-2 to determine viral survival on the surface of meat, namely, stew-cut beef and ground beef, and commonly used meat packaging materials, such as plastic wrap, meat-absorbent material, and Styrofoam. From our studies, we observed the infectivity of MHV inoculated on ground beef and stew-cut beef for 48 h and saw no significant loss in infectivity for MHV from 0 to 6 h postinoculation (hpi) (unpaired t test). However, beginning at 9 hpi, viral infectivity steadily decreased, resulting in a 1.12-log reduction for ground beef and a 0.46-log reduction for stew-cut beef by 48 hpi. We also observed a significant persistence of MHV on meat packaging materials, with Styrofoam supporting the highest viability (3.25 × 103 ± 9.57 × 102 PFU/mL, a 0.91-log reduction after 48 hpi), followed by meat-absorbent material (75 ± 50 PFU/mL, a 1.10-log reduction after 48 hpi), and lastly, plastic wrap (no detectable PFU after 3 hpi, a 3.12-log reduction). Despite a notable reduction in infectivity, the virus was able to survive and remain infectious for up to 48 h at 7°C on four of the five test surfaces. Our results provide evidence that coronaviruses, such as SARS-CoV-2, could potentially survive on meat, meat-absorbent materials. and Styrofoam for up to 2 days, and potentially longer. IMPORTANCE The meat industry has been faced with astronomical challenges with the rampant spread of COVID-19 among meat processing plant workers. This has resulted in meat processing and packaging plant closures, creating bottlenecks everywhere in the chain, from farms to consumers, subsequently leading to much smaller production outputs and higher prices for all parties involved. This study tested the viability of meat and meat packaging materials as potential reservoirs for SARS-CoV-2, allowing the virus to survive and potentially spread among the workers. We used murine hepatitis virus (MHV) as a biosafety level 2 (BSL2) surrogate for SARS-CoV-2. Our results suggest that ground beef, stew-cut beef, meat-absorbent material, and Styrofoam can harbor coronavirus particles, which can remain viable for at least 48 h. Furthermore, our study provides evidence that the environmental and physical conditions within meat processing facilities can facilitate the survival of viable virus.