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United States Department of Agriculture

Agricultural Research Service

Research Project: USDA Swine Influenza a Virus Surveillance System: Extension To: in Vivo Pathogenesis and Transmission and Associated in Vitro Studies Project Number: 5030-32000-108-30
Project Type: Interagency Reimbursable Agreement

Start Date: Mar 01, 2014
End Date: Feb 28, 2016

Objective:
In vitro and in vivo study of swine influenza viruses identified in the USDA Swine Influenza Virus (SIV) Surveillance System.

Approach:
The USDA SIV Surveillance System was initiated in 2009 and over 2000 SIV isolates have entered into the system with their associated sequences. A consistent and continued assessment of viruses from the surveillance system is required for identifying those that require further experimental analysis. Since 2009, repeated occurrences of high profile influenza events with direct or potential impact on the swine industry have been documented, such as the swine-associated variant H3N2v and other sporadic variant virus infections in humans and the H7N9 outbreak in humans in China. Although H7N9 has not yet been detected in swine, there is legitimate concern over whether pigs are susceptible to the virus which has been shown to have known mammalian adaptation markers in the genome and has infected over 100 humans at this time. NADC is uniquely poised to respond to these events and the needs of the industry and other stakeholders through in vitro analysis as well as in vivo pathogenesis, transmission, and vaccine studies at BSL-2 or BSL-3Ag containment. NADC’s partnership with NVSL, NSU, and NAHLN, along with CDC, has been successful in identifying viruses for further investigation, leading to significant findings on the genetic make up of circulating SIV, including reassortants between endemic viruses and the H1N1pdm09, characterizing their phenotype in pigs, and evaluating the efficacy of vaccines against emerging variants identified from the surveillance system. These findings were made public through routine internal teleconferences, meetings, and ultimately in peer-reviewed publications. NADC has established baseline sequence analyses, reference antiserum panels for antigenic analysis, as well as infection and vaccine study models from which to evaluate further evolution of viruses identified in the surveillance system in addition to avian or human viruses of potential risk to the swine population. From the sequence analysis, viruses with unique genetic characteristics are selected for associated in vitro and in vivo study. Additionally, influenza A virus isolates may be identified through public health investigations of zoonotic transmission events or from the animal health sector for unusual phenotypes or evasion of vaccine immunity. The studies funded in this interagency agreement include in vivo and in vitro pathogenesis and transmission, antigenic characterization, or vaccine protection experiments. Continued funding for studies to augment and complement the surveillance system are critical to the overall success and output of the system and should continue to be funded for the duration of the program.

Last Modified: 10/25/2014
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