Evaluation of the effects of animal age, concurrent bacterial infection, and pathogenicity of porcine reproductive and respiratory syndrome virus on virus concentration in pigs
- 1 March 2006
- journal article
- Published by American Veterinary Medical Association (AVMA) in American Journal of Veterinary Research
- Vol. 67 (3), 489-493
- https://doi.org/10.2460/ajvr.67.3.489
Abstract
Objective—To evaluate the influences of animal age, bacterial coinfection, and porcine reproductive and respiratory syndrome virus (PRRSV) isolate pathogenicity on virus concentration in pigs. Animals—Twenty-one 2-month-old pigs and eighteen 6-month-old pigs. Procedure—Pigs were grouped according to age and infected with mildly virulent or virulent isolates of PRRSV. The role of concurrent bacterial infection was assessed by infecting selected pigs with Mycoplasma hyopneumoniae 21 days prior to inoculation with PRRSV. On alternating days, blood and swab specimens of nasal secretions and oropharyngeal secretions were collected. On day 21 after inoculation with PRRSV, selected tissues were harvested. Concentrations of PRRSV were determined by use of quantitative real-time PCR and expressed in units of TCID50 per milliliter (sera and swab specimens) or TCID50 per gram (tissue specimens). Results—Concentrations of virus were higher in blood and tonsils of pigs infected with virulent PRRSV. Pigs infected with virulent PRRSV and M hyopneumoniae had significantly higher concentrations of viral RNA in lymphoid and tonsillar tissue. Coinfection with M hyopneumoniae resulted in a higher viral load in oropharyngeal swab specimens and blood samples, independent of virulence of the PRRSV isolate. Two-month-old pigs had significantly higher viral loads in lymph nodes, lungs, and tracheal swab specimens than did 6-month-old pigs, independent of virulence of the PRRSV isolate. Conclusions and Clinical Relevance—Multiple factors affect PRRSV concentration in pigs, including pathogenicity of the PRRSV isolate, age, and concurrent infection with M hyopneumoniae.Keywords
This publication has 9 references indexed in Scilit:
- Pathogenic and humoral immune responses to porcine reproductive and respiratory syndrome virus (PRRSV) are related to viral load in acute infectionVeterinary Immunology and Immunopathology, 2004
- The Level of Virus-Specific T-Cell and Macrophage Recruitment in Porcine Reproductive and Respiratory Syndrome Virus Infection in Pigs Is Independent of Virus LoadJournal of Virology, 2004
- Evolution of Porcine Reproductive and Respiratory Syndrome Virus during Sequential Passages in PigsJournal of Virology, 2002
- Appearance of Novel PRRSV Isolates by Recombination in the Natural EnvironmentAdvances in experimental medicine and biology, 2001
- Effects of intranasal inoculation of porcine reproductive and respiratory syndrome virus, Bordetella bronchiseptica, or a combination of both organisms in pigsAmerican Journal of Veterinary Research, 2000
- Application of a Nested Polymerase Chain Reaction Assay to Detect Mycoplasma Hyopneumoniae from Nasal SwabsJournal of Veterinary Diagnostic Investigation, 1999
- Evaluation of the effects of nursery depopulation on the profitability of 34 pig farmsVeterinary Record, 1997
- Comparative Pathogenicity of Nine US Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) Isolates in a Five-Week-Old Cesarean-Derived, Colostrum-Deprived Pig ModelJournal of Veterinary Diagnostic Investigation, 1996
- Comparison of the Pathogenicity of Two US Porcine Reproductive and Respiratory Syndrome Virus Isolates with that of the Lelystad VirusVeterinary Pathology, 1995