Survival of influenza virus H1N1 and murine norovirus in raw milk cheeses
Bibliographic record
Abstract
ABSTRACT 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. IMPORTANCE The 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.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".