title: Retention of ingested porcine reproductive and respiratory syndrome virus in houseflies.
abstract: OBJECTIVE
  To evaluate retention of porcine reproductive and respiratory syndrome virus (PRRSV) in houseflies for various time frames and temperatures.
  
  
  METHODS
  Fifteen 2-week-old pigs, two 10-week-old pigs, and laboratory-cultivated houseflies.
  
  
  METHODS
  In an initial experiment, houseflies were exposed to PRRSV; housed at 15 degrees, 20 degrees, 25 degrees, and 30 degrees C; and tested at various time points. In a second experiment to determine dynamics of virus retention, houseflies were exposed to PRRSV and housed under controlled field conditions for 48 hours. Changes in the percentage of PRRSV-positive flies and virus load per fly were assessed over time, and detection of infective virus at 48 hours after exposure was measured. Finally, in a third experiment, virus loads were measured in houseflies allowed to feed on blood, oropharyngeal washings, and nasal washings obtained from experimentally infected pigs.
  
  
  RESULTS
  In experiment 1, PRRSV retention in houseflies was proportional to temperature. In the second experiment, the percentage of PRRSV-positive houseflies and virus load per fly decreased over time; however, infective PRRSV was found in houseflies 48 hours after exposure. In experiment 3, PRRSV was detected in houseflies allowed to feed on all 3 porcine body fluids.
  
  
  CONCLUSIONS
  For the conditions of this study, houseflies did not support PRRSV replication. Therefore, retention of PRRSV in houseflies appears to be a function of initial virus load after ingestion and environmental temperature. These factors may impact the risk of insect-borne spread of PRRSV among farms.
authors.affiliation: Swine Disease Eradication Center, College of Veterinary Medicine, University of Minnesota, Saint Paul, MN 55108, USA.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Schurrer
authors.forename: Scott A
authors.initials: SA
authors.lastname: Dee
authors.forename: Roger D
authors.initials: RD
authors.lastname: Moon
authors.forename: Michael P
authors.initials: MP
authors.lastname: Murtaugh
authors.forename: Colleen P
authors.initials: CP
authors.lastname: Finnegan
authors.forename: John
authors.initials: J
authors.lastname: Deen
authors.forename: Steven B
authors.initials: SB
authors.lastname: Kleiboeker
authors.forename: Carlos B J
authors.initials: CB
authors.lastname: Pijoan
mesh_terms: D000818:Animals; D001826:Body Fluids / Q000821:virology; D017931:DNA Primers; D006793:Houseflies / Q000821:virology*; D019318:Porcine Reproductive and Respiratory Syndrome / Q000635:transmission*; D019316:Porcine respiratory and reproductive syndrome virus / Q000235:genetics*; D012044:Regression Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013552:Swine; D013553:Swine Diseases / Q000635:transmission* / Q000821:virology*; D013696:Temperature; D013997:Time Factors; D019562:Viral Load
chemical_list: D017931:DNA Primers