Foot-and-mouth disease (FMD) is a highly contagious and economically important viral disease of cloven-hoofed animals, including domestic and wild host species. During recent FMD outbreaks in India, spontaneous abortions were reported amongst FMD-affected and asymptomatic cows. The current study was an opportunistic investigation of these naturally occurring bovine abortions to assess causality of abortion and vertical transmission of FMDV from infected cows to fetuses. For this purpose, fetal tissue samples of eight abortuses (heart, liver, kidney, spleen, palatine tonsil, umbilical cord, soft palate, tongue, lungs, and submandibular lymph node) were collected and screened by various detection methods, including viral genome detection, virus isolation, and immunomicros. Amongst these cases, gross pathological changes were observed in 3 abortuses. Gross pathological findings included blood-tinged peritoneal and pleural effusions and myocarditis. Hearts of infected calves had mild to moderate degeneration and necrosis of the myocardium with moderate infiltration by mixed inflammatory cells. Localization of FMDV antigen was demonstrated in lungs and soft palate by immunomicros. FMDV serotype O viral genome was recovered from 7 of 8 cases. Infectious FMDV serotype O was rescued by chemical transfection of the total RNA extracted from three soft palate samples and was sequenced to confirm 100% identity of the VP1 (capsid) coding region with isolates collected from infected cattle during the acute phase of infection. Based upon these findings, it may be concluded that FMDV-associated abortion occurred among the infected pregnant cows included within this study and FMDV was subsequently transmitted vertically to fetuses. This is the first documentation of FMDV-associated abortions in cattle.
Bibliographical noteFunding Information:
This work was funded by the Indian Council of Agricultural Research, New Delhi. Additional funding was provided by Agricultural Research Service-Current Research information System Project 1940-32000-057-00D and the United States Department of State, Biosecurity Engagement Program through the United States Department of Agriculture, Agricultural Research Service Office of International Research Programs. The funding sources had no role in study design, data collection and analysis or the decision to publish the work. CS is a recipient of a Plum Island Animal Disease Center Research Participation Program fellowship, administered by the Oak Ridge Institute for Science and Education (ORISE, www.orau.org) through an interagency agreement with the US Department of Energy. We are thankful to staff of experimental dairy farm for their invaluable cooperation during this study. Technical assistance of Mr. Basant, Uttam Nath Goswami, Shyam Lal Tamta, and Mr. B. Das are highly acknowledged. Steven Pauszek and Michael Eschbaumer are acknowledged for review of the manuscript. CS was a recipient of PIADC Research Participation Program fellowships, administered by the Oak Ridge Institute for Science and Education (ORISE) through an interagency agreement with the U.S. Department of Energy. The Office of International Research Programs, Agricultural Research Service USDA facilitated funding from the Biological Engagement Program, Department of State.