Skip to main content

Impact of #pH and #temperature in dairy #processing on the infectivity of #H5N1 avian #influenza viruses

Image
By G.M.

Abstract

Highly pathogenic avian influenza viruses (HPAIV) of subtype H5N1 (clade 2.3.4.4b) have crossed the species barrier and caused a mastitis-like infection in dairy cows. The high levels of infectious virus found in the milk raised considerable concerns about the safety of raw milk products. This study examined the effect of temperature and pH on the stability of HPAIV and low-pathogenic avian influenza viruses (LPAIV). We found that H5N1 HPAIV remained infectious in milk at 4 degrees Celsius for four weeks, with slow decreases at 21 degrees Celsius, and complete inactivation at 37 degrees Celsius after four weeks. H5N1 LPAIV was stable at 50 degrees Celsius for 30 minutes but inactivated at higher temperatures (55 degrees Celsius for 10 minutes, 60 degrees Celsius for 1 minute, or 72 degrees Celsius for 30 seconds). At pH levels between 6 and 10, the virus remained stable but was partially inactivated at pH 5.0 and completely inactivated at pH 4.0. During yogurt production, H5N1 LPAIV was completely inactivated when the pH reached 4.3. In cheese production, the lowest pH reached was between 5.0 and 5.3. When H5N1 LPAIV was incubated with soft and semi-hard cheese for one day at 4 degrees Celsius, infectious virus titers decreased by 5.1 and 3.9 log10, respectively. When H5N1 LPAIV was incubated with buffer adjusted to pH 5.0, infectious virus titer dropped by only 3.3 log10, suggesting that, alongside pH, other processes of cheese ripening likely influence virus stability. In conclusion, H5N1 avian influenza viruses are largely inactivated during lactic acid fermentation of raw milk. Future studies will assess the required cheese ripening time for complete inactivation.

Source: BioRxIV, https://www.biorxiv.org/content/10.1101/2025.03.21.644501v1

____

Labels

Labels:

Comments

Post a Comment

Popular posts from this blog

#USA, APHIS Confirms {Avian #Influenza #H5N1} #D11 #Genotype in Dairy #Cattle in #Nevada

By G.M.
On January 31, 2025, the USDA Animal and Plant Health Inspection Service (APHIS) National Veterinary Services Laboratories (NVSL) confirmed by whole genome sequence the first detection of highly pathogenic avian influenza (HPAI) H5N1 clade 2.3.4.4b, genotype D1.1 in dairy cattle .  This confirmation was a result of State tracing and investigation, following an initial detection on silo testing under the USDA’s National Milk Testing Strategy (NMTS) in Nevada.  USDA APHIS continues to work with the Nevada Department of Agriculture by conducting additional on-farm investigation, testing, and gathering additional epidemiological information to better understand this detection and limit further disease spread.  This is the first detection of this virus genotype in dairy cattle (all previous detections in dairy cattle have been HPAI H5N1 clade 2.3.4.4b, genotype B3.13 ).  Genotype D1.1 represents the predominant genotype in the North American flyways this past fall an...
Post a Comment
Read more »

#USA, After #Birdflu Detected in Local #Cat, County #Health Officials Say #Pet Owners Should Contact Veterinarian When Their Pets are Sick

By G.M.
Redwood City — State veterinary and health officials have confirmed a case of H5N1 (bird flu) in a domestic stray cat in San Mateo County.  The infection, which is not related to the recent instance of bird flu in a backyard flock , was found in a stray cat in Half Moon Bay that had been taken in by a family .  When it showed symptoms, they took it to Peninsula Humane Society, whose veterinarians examined it and requested testing. Lab results confirmed H5N1.  It is not known how the cat was infected and it was euthanized due to its condition. Cats may be exposed to bird flu by consuming infected bird , being in environments contaminated with the virus and consuming unpasteurized milk from infected cows or raw food. Inside domestic animals, such as cats and dogs, that go outside are also at risk of infection.​​​​​​​ According to the Centers for Disease Control and Prevention, the risk of cats spreading H5N1 to people is extremely low, though it is possible for cats to spre...
Post a Comment
Read more »

#USA, Novel #Influenza A #H5N1 Virus: One Pediatric Case in #California {FluView}

By G.M.
 {Excerpt} One confirmed human infection with influenza A(H5) virus was reported to CDC this week. To date, human-to-human transmission of influenza A(H5) virus has not been identified in the United States. This case was reported by the California Department of Public Health and occurred in a child less than 18 years old with no known contact with influenza A(H5N1) virus-infected animals or humans . The investigation into the source of infection for this case is ongoing , and no human-to-human transmission has been identified. A specimen from the individual was tested at a public health laboratory using the CDC influenza A(H5) assay before being sent to CDC for further testing. The specimen was positive for influenza A(H5) virus using diagnostic RT-PCR at CDC. Additional analysis including genetic sequencing is underway. In response to this detection, additional case investigation and contact monitoring are being conducted by public health officials in California. There have now be...
Post a Comment
Read more »