Virulence beneath the fleece; a tale of foot-and-mouth disease virus pathogenesis in sheep

PLoS One. 2019 Dec 31;14(12):e0227061. doi: 10.1371/journal.pone.0227061. eCollection 2019.

Abstract

Foot-and-mouth disease virus (FMDV) is capable of infecting all cloven-hoofed domestic livestock species, including cattle, pigs, goats, and sheep. However, in contrast to cattle and pigs, the pathogenesis of FMDV in small ruminants has been incompletely elucidated. The objective of the current investigation was to characterize tissue- and cellular tropism of early and late stages of FMDV infection in sheep following three different routes of simulated natural virus exposure. Extensive post-mortem harvest of tissue samples at pre-determined time points during early infection (24 and 48 hours post infection) demonstrated that tissues specifically susceptible to primary FMDV infection included the paraepiglottic- and palatine tonsils, as well as the nasopharyngeal mucosa. Additionally, experimental aerosol inoculation of sheep led to substantial virus replication in the lungs at 24-48 hours post-inoculation. During persistent infection (35 days post infection), the paraepiglottic- and palatine tonsils were the only tissues from which infectious FMDV was recovered. This is strikingly different from cattle, in which persistent FMDV infection has consistently been located to the nasopharyngeal mucosa. Analysis of tissue sections by immunomicroscopy revealed a strict epithelial tropism during both early and late phases of infection as FMDV was consistently localized to cytokeratin-expressing epithelial cells. This study expands upon previous knowledge of FMDV pathogenesis in sheep by providing detailed information on the temporo-anatomic distribution of FMDV in ovine tissues. Findings are discussed in relation to similar investigations previously performed in cattle and pigs, highlighting similarities and differences in FMDV pathogenesis across natural host species.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adenoids / pathology
  • Adenoids / virology*
  • Animals
  • Cattle
  • Foot-and-Mouth Disease / pathology
  • Foot-and-Mouth Disease / virology*
  • Foot-and-Mouth Disease Virus / isolation & purification
  • Foot-and-Mouth Disease Virus / pathogenicity*
  • Male
  • Palatine Tonsil / pathology
  • Palatine Tonsil / virology*
  • Respiratory Mucosa / pathology
  • Respiratory Mucosa / virology
  • Sheep / virology*
  • Species Specificity
  • Swine
  • Virulence
  • Virus Replication

Grants and funding

This study was a collaboration between The Commonwealth Scientific and Industrial Research Organisation (CSIRO)-Australian Animal Health Laboratory (AAHL) and the Agricultural Research Service (ARS) of the US Department of Agriculture (USDA), who co-funded the work. Funding through CSIRO (NS, WV) was provided in part by the livestock industries in Australia through Animal Health Australia (AHA). The relevant industry bodies are the Cattle Council of Australia, Australian Dairy Farmers, Australian Lot Feeders Association, Wool Producers Australia, Sheepmeat Council of Australia, Australian Pork Limited and the Goat Industry Council of Australia. The AHA funds were matched through the Meat and Livestock Australia (MLA) Donor Company by the Australian Government under MLA Project P.PSH 0652. Additional funding came from USDA ARS (LR, JA) current research information system Project 1940- 32000-057-00D. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.