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.

This is not quite an "applied" research, but it is good to know that such technologies are being evaluated and therefore available for "commercial" use soon:

A multiplex method for the simultaneous serological detection of porcine reproductive and respiratory syndrome virus and porcine circovirus type 2.

Lin K, Wang C, Murtaugh MP, Ramamoorthy S.

Source

Department of Veterinary Diagnostic and Production Animal Medicine, Veterinary Diagnostic Laboratory, Iowa State University, Ames, IA 50011.

Abstract

Porcine circovirus type 2 (PCV2) and porcine reproductive and respiratory syndrome virus (PRRSV) are major contributors to the porcine respiratory disease complex (PRDC). Routine serological diagnosis and surveillance play an important role in the prevention of PRDC as it is a leading cause of economic losses to the swine industry. We herein describe an advanced microsphere-based immunoassay that permits the simultaneous detection of antibodies to PCV2 and PRRSV; thereby reducing the time and effort involved in testing. Recombinant PRRSV N protein antigen and the PCV2 capsid antigen were coupled to fluorophore dyed beads with distinct spectral addresses. Weekly sera samples from 72 pigs that were experimentally exposed to either PCV2, PRRSV or both PCV2 and PRRSV were used to validate the microbead assay (MBA) in comparison with the gold-standard ELISAs. The kinetics of the PCV2 and PRRSV-specific antibody responses as measured by the microbead assay was comparable to those of the standard assays; Spearman's Rank correlation was 0.72 (p<0.001) for PRRSV and 0.80 (p<0.001) for PCV2. Diagnostic sensitivity and specificity were determined using field sera whose positive or negative status was determined by the standard tests. The diagnostic sensitivity and specificity were both 98% for PCV2 and were 91% and 93% for PRRSV (Kappa coefficient: 0.85 and 0.67 for PCV2 and PRRSV respectively). Multiplexing did not interfere with assay performance or diagnostic sensitivity. Therefore, the described study demonstrates proof of concept for the development of more versatile and economical microbead array based multiplex serological test panels for veterinary use.

Reference:
Lin K, Wang C, Murtaugh M P, Ramamoorthy S. A multiplex method for the simultaneous serological detection of porcine reproductive and respiratory syndrome virus and porcine circovirus type 2. Journal of clinical microbiology 2011 [accepted]

Clustering of and Risk Factors for the Porcine High Fever Disease in a Region of Vietnam

This paper is about risk factors associated with PHFD. It has been suggested that PRRSv might be associated with PHFD, so I included this paper in our blog. In fact, results of this study are in line with what has been reported for PRRSv in terms of risk factors associated with infection and clinical severity of the disease.
Enjoy:

ABSTRACT
Porcine high fever disease (PHFD) emerged in 2006 in China and spread to Vietnam. Little work has been carried out to investigate PHFD risk factors and space–time dynamics. To fill this gap, we investigated probable cases of PHFD at household level as the outcome. A study area, approximately 100 sq. km, was selected from a province of southern Vietnam that had reported the out- break of PHFD in 2008. A survey was conducted in the study area to collect information about swine health problems during 2008. The questionnaire included three sections: general information, clinical signs of disease in pigs and production factors believed to be risk factors. Cases were defined at the household level and included interpretation of clinical signs in series. Logistic regression with a random intercept at the hamlet level was used to assess risk factors for PHFD at the household level. Spatial clustering was investigated using the D-function and a Cuzick–Edward’s test. Spatial clusters were evalu- ated using a spatial relative risk surface and the spatial scan statistic using a Bernoulli model. Space–time clustering was explored using a space–time K-function and Knox’s test. Space–time clusters were evaluated using a space– time permutation model in SaTScan. Of 955 households with questionnaire data, 33.4% were classified as cases. The statistical significance of space and space–time clustering differed between methods employed. The risk factors associated with occurrence of cases were higher numbers of sows and finishing pigs (log 2 transformed), receiving pigs from an external source and the inter- action between using ‘water green crop’ (WGC) as pig feed and owning ducks with or without direct contact with pigs. The interaction between the presence of ducks and feeding WGC to pigs suggested the involvement of pathogens that might be present in water (environment) and could further replicate in or on ducks.

REFERENCE:
Le H, Poljak Z, Deardon R, Dewey C E. Clustering of and Risk Factors for the Porcine High Fever Disease in a Region of Vietnam. Transboundary and emerging diseases 2011; doi:10.1111/j.1865-1682.2011.01239.x.