Downtime for PRRSv+Myco

Pitkin A, Otake S, Dee S. A one-night downtime period prevents the spread of porcine reproductive and respiratory syndrome virus and Mycoplasma hyopneumoniae by personnel and fomites (boots and coveralls). J Swine Health Prod. 2011;19(6):345–348.

Summary

This paper summarizes observations recorded over a 4-year (1438-day) period regarding the ability of a 1-night period of downtime [+ shower and cloth-change] to prevent mechanical spread of porcine repro- ductive and respiratory syndrome virus and Mycoplasma hyopneumoniae between pig populations by personnel and fomites.

Keywords: swine, porcine reproductive and respiratory syndrome, downtime, personnel, fomites

Effect of PRRSv vaccine on the shedding of wild-type virus from an infected population of growing pigs

Linhares D C, Cano J P, Wetzell T, Nerem J, Torremorell M, Dee S A. Effect of modified-live porcine reproductive and respiratory syndrome virus (PRRSv) vaccine on the shedding of wild-type virus from an infected population of growing pigs. Vaccine 2011 [in press]

Abstract

There are ongoing efforts to eliminate porcine reproductive and respiratory syndrome virus (PRRSv) from regions in the United States swine industry. However, an important challenge for the accomplishment of those efforts is the re-infection of pig units due to the area spread of PRRSv. The objective of this study was to evaluate the effect of PRRS modified-live virus vaccine (MLV) on viral shedding and on dynamics of PRRSv infection in pig populations raised under commercial conditions. The study composed of two rooms of 1000 pigs each. Ten percent of pigs of each room were inoculated with a field isolate of PRRSv. Rooms had separate air spaces and strict scientifically validated biosecurity protocols were adopted to avoid movement of pathogens between rooms. At 8 and 36dpi (days post inoculation), all pigs of the challenge-vaccine group were inoculated with a MLV vaccine. Pigs of the challenge-control group were placebo-inoculated. Blood and oral fluid samples were collected from each room at 0, 8, 36, 70, 96 and 118dpi for PRRSv RNA detection using PCR. PRRSv-antibodies were also screened from blood serum samples with a commercially available ELISA test. Additionally, tonsil scraping samples were collected from both groups at 70, 96 and 118dpi. Moreover, air samples were collected 6 times per week from 0 to 118dpi and were tested for PRRSv RNA using qPCR assay. There was no difference in the PRRSv infection dynamics measured as duration and magnitude of viremia and seroconversion. Also, there was no difference in the frequency of tonsil scraping samples PRRSv-positive by PCR. However, the challenge-vaccine group had significantly less PRRSv shed compared to the challenge-control group. The challenge-vaccine group had significant less PRRSv-positive oral fluids at 36dpi. Moreover, the challenge-vaccine group had significant reduction in the cumulative PRRSv shed in the air.

Copyright © 2011. Published by Elsevier Ltd.

PMID:

 

22063389

 

[PubMed]

Can we vaccinate pigs via their feed?

Maybe in the near future... see abstract below.

Planta. 2011 Oct 5. [Epub ahead of print]

Expression of the nucleocapsid protein of Porcine Reproductive and Respiratory Syndrome Virus in soybean seed yields an immunogenic antigenic protein.

Vimolmangkang S, Gasic K, Soria-Guerra R, Rosales-Mendoza S, Moreno-Fierros L, Korban SS.

Source

Department of Natural Resources and Environmental Sciences, University of Illinois, Urbana, IL, 61801, USA.

Abstract

Porcine reproductive and respiratory syndrome (PRRS), caused by the PRRS virus (PRRSV), is a serious disease of swine and contributes to severe worldwide economic losses in swine production. Current vaccines against PRRS rely on the use of an attenuated-live virus; however, these are unreliable. Thus, alternative effective vaccines against PRRS are needed. Plant-based subunit vaccines offer viable, safe, and environmentally friendly alternatives to conventional vaccines. In this study, efforts have been undertaken to develop a soybean-based vaccine against PRRSV. A construct carrying a synthesized PRRSV-ORF7 antigen, nucleocapsid N protein of PRRSV, has been introduced into soybean, Glycine max (L.) Merrill. cvs. Jack and Kunitz, using Agrobacterium-mediated transformation. Transgenic plants carrying the sORF7 transgene have been successfully generated. Molecular analyses of T(0) plants confirmed integration of the transgene and transcription of the PRRSV-ORF7. Presence of a 15-kDa protein in seeds of T(1) transgenic lines was confirmed by Western blot analysis using PRRSV-ORF7 antisera. The amount of the antigenic protein accumulating in seeds of these transgenic lines was up to 0.65% of the total soluble protein (TSP). A significant induction of a specific immune response, both humoral and mucosal, against PRRSV-ORF7 was observed following intragastric immunization of BALB/c female mice with transgenic soybean seeds. These findings provide a 'proof of concept', and serve as a critical step in the development of a subunit plant-based vaccine against PRRS.

A four-year summary of air filtration system efficacy for preventing airborne spread of porcine reproductive and respiratory syndrome virus and Mycoplasma hyopneumoniae

Summary
A 4-year study evaluated the ability of commercial air filters to protect susceptible populations against airborne transmission
of porcine reproductive and respiratory syndrome virus and Mycoplasma hyopneu- moniae. All filter types*, equally reduced the risk of airborne transmission of both pathogens, compared to non-filtered controls, supporting further application in the field.
Keywords: swine, porcine reproductive and respiratory syndrome virus, airborne, trans- mission, filtration



Dee S, Pitkin A, Otake S, et al. A four-year summary of air filtration system efficacy for preventing airborne spread of porcine reproductive and respiratory syndrome virus and Mycoplasma hyopneumoniae. J Swine Health Prod. 2011;19(5):292–294. 




* types of filters evaluated:
     - mechanical: MERV14 and MERV 16
     - electrostatic
     - chemical

Assessment of Stomoxys calcitrans (Diptera: Muscidae) as a vector of porcine reproductive and respiratory syndrome virus

Abstract

Porcine Reproductive and respiratory syndrome (PRRS) is a globally significant swine disease caused by an arterivirus. The virus replicates in alveolar macrophages of infected pigs, resulting in pneumonia in growing pigs and late-term abortions in sows. Outbreaks occur on disparate farms within an area despite biosecurity measures, suggesting mechanical transport by arthropods. We investigated the vector potential of stable flies, Stomoxys calcitrans (L.) (Diptera: Muscidae), in the transmission of porcine reproductive and respiratory syndrome virus (family Arteriviridae, genus Arterivirus, PRRSV) under laboratory conditions. Stable flies were collected around PRRS-negative boar stud barns in North Carolina and tested for presence of the virus. Stable flies were collected on alsynite traps placed near the exhaust fan of the close-sided tunnel-ventilated buildings, suggesting blood seeking flies are attracted by olfactory cues. No flies were positive for PRRSV. We assessed transmission of the virus through an infective bite by feeding laboratory reared stable flies on blood containing virus and transferring them to naive pigs for subsequent bloodmeals. Transmission of the virus to naive pigs by infective bites failed in all attempts. The volume of blood contained within the closed mouthparts of the stable fly seems to be insufficient to deliver an infective dose of the virus. Stable flies are unlikely to transmit PRRSV from one pig to another while blood feeding. The fate of the virus after a bloodmeal remains to be determined.

Rochon K, Baker R B, Almond G W, Watson D W. Assessment of Stomoxys calcitrans (Diptera: Muscidae) as a vector of porcine reproductive and respiratory syndrome virus. Journal of medical entomology 2011;48(4):876-883.

Vet Microbiol. 2011 Jul 1. [Epub ahead of print]

Comparative pathogenicity of type 1 and type 2 isolates of porcine reproductive and respiratory syndrome virus (PRRSV) in a young pig infection model.

Martínez-Lobo FJ, Díez-Fuertes F, Segalés J, García-Artiga C, Simarro I, Castro JM, Prieto C.

Source

Dpto. Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, 28040 Madrid, Spain.

Abstract

Porcine reproductive and respiratory syndrome virus (PRRSV) isolates are classified in two different genotypes, based on genomic heterogeneity: type 1, which comprises European type isolates, and type 2, which includes North American type isolates. It is believed that members of both genotypes differ in some biological properties including pathogenicity, however extensive studies comparing isolates of both genotypes have never been carried out. The objective of the present study was to compare the pathogenic properties of six different PRRSV isolates, three of type 1 and three of type 2, in a young pig infection model. For this purpose, a total of 105 3-week-old piglets were divided in 7 groups of 15 animals that were exposed on day 0 of the experiment to one of the six isolates tested or were mock infected (negative control group). Clinical signs and rectal temperatures were recorded daily and blood samples were taken on days 3, 6, 9, 12, 15, 18 and 21 of the experiment. On days 7, 14 and 21 post-inoculation five animals per group were sacrificed, macroscopic lung lesions were evaluated and different tissue samples were collected to determine viral organic distribution. The results obtained indicate that type 2 isolates are more pneumovirulent than type 1 isolates, as demonstrated by the recording of respiratory clinical signs only in pigs exposed to type 2 viruses and by the severity of macroscopic and microscopic lung lesions in those pigs. However, no clear differences could be established between genotypes in systemic clinical signs or viral load and viral distribution after challenge. These results support the general idea that type 2 isolates induce more severe respiratory disease than type 1 isolates.

Copyright © 2011 Elsevier B.V. All rights reserved.

PMID:

 

21831539

 

[PubMed - as supplied by publisher]

Clin Vaccine Immunol. 2011 Aug 10. [Epub ahead of print]

Effect of the modified live porcine reproductive and respiratory syndrome virus (PRRSV) vaccine on European and North American PRRSV shedding in semen from infected boars.

Han K, Seo HW, Shin JH, Oh Y, Kang I, Park C, Chae C.

Source

Department of Veterinary Pathology, College of Veterinary Medicine, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151-742, Republic of Korea.

Abstract

The objective of the present study was to compare the effects of the modified live porcine reproductive and respiratory syndrome virus (PRRSV) vaccine (Ingelvac PRRS MLV, Boehringer Ingelheim Animal Health, St. Joseph, MO, USA) on European and North American PRRSV shedding in the semen of experimentally infected boars. The boars were randomly divided into six groups. Vaccinated boars shed the North American PRRSV at the rate of 10(0.1) to 10(1.0) viral genome copies per ml and 3.63 to 10(1.1) 50% tissue culture infective doses (TCID(50))/ml, respectively in semen, whereas non-vaccinated boars shed the North American PRRSV at the rate of 10(0.2) to 10(4.7) viral genome copies per ml and 1.14 to 10(3.07) TCID(50)/ml, respectively in semen. Vaccinated boars shed the European PRRSV at the rate of 10(0.1) to 10(4.57) viral genome copies per ml and 1.66 to 10(3.10) TCID(50)/ml, respectively in semen, whereas non-vaccinated boars shed the European PRRSV at the rate of 10(0.3) to 10(5.14) viral genome copies per ml and 1.69 to 10(3.17) TCID(50)/ml, respectively in semen. The number of genomic copies of the European PRRSV in semen samples was not significantly different between vaccinated and non-vaccinated challenged European PRRSV boars. The present study demonstrated that boar vaccination using commercial modified live PRRSV vaccine was able to decrease subsequent shedding of North American PRRSV in semen after challenge but was unable to decrease shedding of European PRRSV in semen after challenge.