Blondin-Brosseau M, Zhang W, Gravel C, Harlow J, L. Survival of influenza virus H1N1 and murine norovirus in raw milk cheeses. Appl Environ Microbiol. 2025 Oct 31:e0188125
The spillover of highly pathogenic avian influenza (HPAI) to dairy cattle and its presence at high titers in raw milk has created a concern that consumption of dairy products made from unpasteurized milk could result in human exposure. We examined whether H1N1, as a surrogate for HPAI viruses, and murine norovirus (MNV), as a surrogate for unenveloped enteric viruses, can survive the cheese-making process by making cream cheese-style and feta-style cheeses from artificially inoculated raw milk. We used the modified ISO 15216 method for viral extraction, which has a limit of detection of 3.0-3.7 log for infectious H1N1 in soft cheeses. Infectious H1N1 virus was detected in the curd from both types of cheeses and in the whey from cream cheese but not in the whey from feta cheese. Infectious MNV particles were detected in the curd and in the whey for both types of cheeses. To study the effect of salt, pH, aging, and microbiome of various unpasteurized milk cheeses on viral survival, we artificially inoculated different commercial unpasteurized milk cheeses with 7 log PFU of H1N1 and 6 log PFU of MNV and examined viral survival over an 8 week period at 4°C. We observed that H1N1 survived for 8 weeks, with an average of 2.6, 2.75, and 4.0 log reductions on cheddar, washed rind firm cheese, and semisoft brie-like cheese, respectively (P < 0.001). The level of infectious H1N1 fell below the limit of detection in cream cheese after 2 weeks of inoculation. It is noteworthy that the sensory qualities of soft and semisoft cheeses deteriorated in 2 weeks, but the sensory qualities of firm cheeses did not change drastically, demonstrating that, as expected, they endure the aging process better than the soft and semisoft cheeses. Furthermore, the limit of detection for soft cheeses is approximately 1 log lower compared to firm cheeses, and the extraction method has a lower efficiency for soft cheeses compared to firm cheeses. MNV survived in firm cheeses for 8 weeks with only 1 log reduction on cheddar cheese and 2 log reductions on the washed rind firm cheese (P < 0.05). The data obtained in this study could help with the risk assessment of dairy products made from unpasteurized milk.IMPORTANCEThe rapid spread of H5N1 viruses among dairy cattle in the United States and the viral shedding at high titers raised concern regarding the safety of dairy products, specifically cheeses made with unpasteurized milk. In this study, we demonstrated that murine norovirus and influenza virus can survive the cheese-making and aging process. Therefore, it is recommended that milk contaminated with viruses be heat-treated to ensure safety.
See Also:
Latest articles in those days:
- Generation of Nasal Cell-Derived Human Alveolar Organoids and Organoid-Macrophage Assembloids for in Vitro Lung Modeling 1 hours ago
- Determinants of the Seasonal Influenza Vaccination Uptake Among People Aged 50 Years or Above During and After the Pandemic: A Systematic Review 13 hours ago
- [preprint]A GIS-based framework for standardized environmental characterization in One-Health surveillance: a case study of HPAI monitoring in wetlands 13 hours ago
- First detection and transatlantic introduction of Influenza A(H3N2) subclade K (J.2.4.1) into Ecuador: insights from genomic sentinel surveillance 14 hours ago
- Assessment of influenza virus and coronavirus tropism, replication competence and disease severity in ex vivo and in vitro cultures of the human respiratory tract 2 days ago
[Go Top] [Close Window]


