Highly Pathogenic Avian Influenza (HPAI) H5N1 virus is an emerging pathogen in dairy cattle with zoonotic potential. Recently, HPAI H5N1 spilled over into dairy cattle and studies demonstrated the tropism of the virus for the mammary gland with the virus replicating in milk secreting cells in this tissue, leading to high levels of virus shedding in milk of affected cows. This property has caused major public health and consumer concerns, as milk and dairy products are consumed in large scale by the population in the US. While pasteurization is designed to reduce potential bacterial and viral pathogens in commercial shelf milk and have been shown to be effective by us and others to inactivate HPAI, raw milk which is handled in large quantities in farms represents a major risk factor for HPAI spread and transmission. Indeed, recent investigations by Dr. Diel’s group and others have shown that raw milk can serve as a route of transmission of the virus to cats. The practice of feeding unpasteurized raw milk to calves and other animals in dairy farms poses a risk for spread and dissemination of the virus. Given the high levels of HPAI virus present in milk from affected animals, disposal of raw non-saleable milk from those animals is a major problem, as the contaminated milk may serve as source of infection to other animals, birds and potentially humans. This needs to be urgently addressed to minimize environmental impact of HPAI and to prevent its spread between dairy farms and from affected dairy farms to other susceptible species. In the present project we will address this significant issue and will perform studies to improve our understanding of the risks posed by raw milk and raw milk cheeses, and to identify potential mitigation strategies to inactivate HPAI in raw milk and raw milk products. To accomplish this, we propose four specific aims: 1) to define efficacy of raw milk cheese aging on inactivation of HPAI; 2) to characterize the thermal inactivation kinetics of HPAI H5N1 in dairy products; 3) to identify effective mitigation strategies to treat raw waste milk prior to disposal or feeding to animals; and 4) to enhance capabilities and capacity for HPAI H5N1 testing in support of FDA’s research agenda. To achieve these goals and establish a long-term partnership with FDA we brought together a transdisciplinary team of investigators with complementary expertise in virology (Drs. Diel and Nooruzzaman), food safety, microbiology and dairy product processing (Drs. Martin and Alcaine), and on farm clinical and management practices (Dr. Mann). Successful completion of the study will provide a comprehensive understanding of the inactivation kinetics and efficiency of inactivation of HPAI in milk and several other dairy products, including high risk products such as raw milk cheeses. Thus, the project is directly aligned with the FDA goals and mission.