Evaluation of the effects of nursery depopulation on the persistence of porcine reproductive and respiratory syndrome virus and the productivity of 34 farms

Dee, Scott; Joo, Heesoo; Polson, Dale; Park, B. K.; Pijoan, Carlos; Molitor, Thomas W.; Collins, James E.; King, Vickie L.

doi:10.1136/vr.140.10.247

Cited by 25 publications

(10 citation statements)

References 2 publications

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“…PRRSV continues to be an economically significant health problem for swine producers worldwide with an estimated reported loss of $228 per inventoried sow (8,9). Immunity to PRRSV has eluded researchers and remains a complicated and poorly understood process.…”

Section: Introductionmentioning

confidence: 99%

γδ Lymphocyte Response to Porcine Reproductive and Respiratory Syndrome Virus

et al. 2005

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Porcine reproductive and respiratory syndrome virus (PRRSV) continues to be one of the most important diseases facing swine industry today. Following PRRSV infection pigs develop both humoral and cell-mediated responses following PRRSV exposure; however, the relative importance in protection and clearance of the virus is not yet completely understood. Swine contain a large percentage of gammadelta T-lymphocytes in peripheral circulation capable of responding to various pathogens in both an innate and specific immune response. The objectives of this study were to determine whether gammadelta lymphocytes functionally respond to PRRSV upon initial exposure and re-exposure. Four month old PRRSV free gilts were intranasally inoculated with a field isolate MN-30100 then assessed at various time points post infection. On day 120, pigs were re-exposed with MN-30100 PRRSV strain and subsequently were bled on days 0, 7, and 14 post re-exposure. Lymphocyte subpopulations, antigen specific proliferation, and IFN-gamma production were evaluated throughout the study. Circulating gammadelta lymphocytes in PRRSV exposed animals expanded between days 14 to 70 (d14-d70, p = 0.016); following antigen stimulation, gammadelta lymphocyte proliferated by day 14 (d0-d14, p = 0.001) continuing through day 60. gammadelta lymphocytes produced IFN-gamma by day 14 pi continuing through day 50 (d0-d50, p = 0.004). Following re-exposure both gammadelta+ and CD4+ lymphocytes increased in IFN-gamma production. These results are not fully conclusive on the role of gammadelta lymphocytes against PRRSV; the data indicate that gammadelta lymphocytes specifically respond to PRRSV.

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Section: Introductionmentioning

confidence: 99%

γδ Lymphocyte Response to Porcine Reproductive and Respiratory Syndrome Virus

et al. 2005

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“…The eradication of PRRS appears to be a difficult issue, at least to date. Some studies have shown that by using management strategies, such as segregated early weaning and other modifications of the 'all-in, all-out' system, the syndrome can be eliminated (Dee et al, 1993(Dee et al, , 1997. However, such strategies are not always successful and cannot be easily applied, depending on the facilities and hardware of each enterprise (Dee et al, 1993(Dee et al, , 1997.…”

Section: Introductionmentioning

confidence: 99%

Field Evaluation of a Live Vaccine against Porcine Reproductive and Respiratory Syndrome in Fattening Pigs

Mavromatis

Kritas

Alexopoulos

et al. 1999

Journal of Veterinary Medicine, Series B

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A live vaccine based on a European isolate of porcine reproductive and respiratory syndrome virus (Porcilis PRRS) was tested in this study in order to determine the protection of fattening pigs against the respiratory form of the syndrome under field conditions. Ten thousand pigs in an infected farm were vaccinated against PRRS virus at the age of 6 weeks and were compared with non‐vaccinated pigs with respect to their health status, mortality, performance parameters (average daily gain, average daily feed intake, feed conversion ratio) and the presence of certain pathogens in their lungs. The results showed that treated pigs became ill less frequently and demonstrated reduced mortality compared with untreated ones. As compared with non‐vaccinated animals, PRRS‐vaccinated pigs also performed in a better way with respect to the feed conversion ratio (P < 0.05) and average daily gain (P < 0.05), while feed intake was similar for both groups (P > 0.05). Bacteriological examinations of the lungs revealed increased incidence of respiratory bacterial infection in untreated pigs compared with treated ones. A tendency for a faster antibody response was also detected in the vaccinees. The results of the present study show that immunization with a live vaccine does protect fattening pigs against the respiratory manifestations of PRRS.

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“…Field evidence strongly suggests that PRRSV infection makes pigs more susceptible to bacterial diseases in nursery and grow-finish pigs (2). Combined porcine reproductive and respiratory syndrome virus (PRRSV) and Streptococcus suis infections are common (10,14,16) and can be especially problematic to control with conventional medication and vaccination regimens (1,15).…”

mentioning

confidence: 99%

Efficacy of Antimicrobial Treatments and Vaccination Regimens for Control of Porcine Reproductive and Respiratory Syndrome Virus and Streptococcus suis Coinfection of Nursery Pigs

Halbur¹,

Thanawongnuwech

Brown

et al. 2000

J Clin Microbiol

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Seventy-six, crossbred, porcine reproductive and respiratory syndrome virus (PRRSV)-free pigs were weaned at 12 days of age and randomly assigned to seven groups of 10 to 11 pigs each. Pigs in group 1 served as unchallenged controls. Pigs in groups 2 to 7 were challenged intranasally with 2 ml of high-virulence PRRSV isolate VR-2385 (104.47 50% tissue culture infective doses per 2 ml) on day 0 of the study (30 days of age). Seven days after PRRSV challenge, pigs in groups 2 to 7 were challenged intranasally with 2 ml of Streptococcus suis serotype 2 (108.30 CFU/2 ml). Group 2 pigs served as untreated positive controls. Antimicrobial treatments included daily intramuscular injection with 66,000 IU of procaine penicillin G per kg of body weight on days 8 to 10 (group 3), drinking water medication with 23.1 mg of tiamulin per kg during days 8 to 10 (group 4), and daily intramuscular injection of 5.0 mg of ceftiofur hydrochloride per kg on days 8 to 10 (group 5). Vaccination regimens included two intramuscular doses of an autogenous killedS. suis vaccine (group 6) prior to S. suischallenge or a single 2-ml intramuscular dose of an attenuated live PRRSV vaccine (group 7) 2 weeks prior to PRRSV challenge. Mortality was 0, 63, 45, 54, 9, 40, and 81% in groups 1 to 7, respectively. Ceftiofur treatment was the only regimen that significantly (P < 0.05) reduced mortality associated with PRRSV and S. suis coinfection. The other treatments and vaccinations were less effective. We conclude that ceftiofur administered by injection for three consecutive days following S. suis challenge was the most effective regimen for minimizing disease associated with PRRSV and S. suiscoinfection.

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Evaluation of the effects of nursery depopulation on the persistence of porcine reproductive and respiratory syndrome virus and the productivity of 34 farms

Cited by 25 publications

References 2 publications

γδ Lymphocyte Response to Porcine Reproductive and Respiratory Syndrome Virus

γδ Lymphocyte Response to Porcine Reproductive and Respiratory Syndrome Virus

Field Evaluation of a Live Vaccine against Porcine Reproductive and Respiratory Syndrome in Fattening Pigs

Efficacy of Antimicrobial Treatments and Vaccination Regimens for Control of Porcine Reproductive and Respiratory Syndrome Virus and Streptococcus suis Coinfection of Nursery Pigs

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