Department of Agriculture scientists developed a detailed map of where foot-and-mouth disease first infects cattle, and they hope the discovery will help efforts to develop new vaccines.
Dr. Jonathan Arzt, a veterinary medical officer with the Agricultural Research Service of the Department of Agriculture, said researchers had long suspected the respiratory tract was the main route of FMD infection in ruminants, but nobody had defined specific events connected with initial infection. He is the lead author of the article "The Early Pathogenesis of Foot-and-Mouth Disease in Cattle After Aerosol Inoculation: Identification of the Nasopharynx as the Primary Site of Infection," which was published in the November 2010 issue of Veterinary Pathology.
Dr. Arzt; Dr. Luis L. Rodriguez, research leader for the Foreign Animal Disease Research Unit; and Dr. Juan M. Pacheco, a research microbiologist—all of whom work at the Plum Island Animal Disease Center in New York—mapped the geographic distribution of the FMD virus in the respiratory tract of newly infected cattle, Dr. Arzt said. The research involved aerosol inoculation of 16 steers, which was intended to simulate natural exposure to the virus, followed by collection of blood, oral swab, nasal swab, and postmortem tissue samples, the article states.
"In previremic steers, FMDV was most consistently localized to nasopharyngeal tissues, thereby indicating this region as the most important site of primary viral replication," the article abstract states.
Current research involves identifying all cell types associated with early events of infection as well as examination of the FMDV genome in hopes of finding portions crucial for virulence, Dr. Arzt said. Information from both sources could help identify ways to block early events needed for infection to occur.
Dr. Arzt said that, after years of work, it has been satisfying to reach milestones such as the publication of the article in Veterinary Pathology. He noted that colleagues in the ARS are also attacking the FMD virus in numerous ways, and he hopes to continue work with the ARS toward developing a next-generation FMD vaccine.