PRRSv in wild boar populations in Korea

Abstract

No information is currently available on porcine reproductive and respiratory syndrome virus (PRRSV) infection in wild boars (Sus scrofa) in Korea. In this study, the status of PRRS in wild boars was investigated. Blood samples were collected from 267 wild boars from eight provinces in Korea. Four of the samples tested (1.5%) were positive for PRRSV antibodies and eight (3.0%) were positive for antigens. Of the virus-positive samples, three and five samples were typed as containing European (EU, type 1) or North American (NA, type 2) viruses, respectively. Two amplicons (one from type 1 and one from type 2) were used to analyze the PRRSV open reading frame 7 (ORF7) sequence. The nucleotide sequences of type 1 PRRSV ORF7 had identities between 96.1% and 98.4% with PRRSVs from domestic pigs in Korea. The sequences of type 2 PRRSV ORF7 had identities of 100% with the PRRSV strain VR-2332, which was prototypic North American strain. These results show that PRRSVs are present in wild boars in Korea, and effective PRRSV surveillance of the wild boar population might therefore be useful for disease control.

PMID:

 

23271179

 

[PubMed - in process]

Choi E, Lee C, Hyun B, Kim J, Lim S, Song J, Shin Y. A survey of porcine reproductive and respiratory syndrome among wild boar populations in Korea. Journal of veterinary science 2012;13(4):377-383.

Immunopathogenesis of PRRSv in the respiratory tract

Abstract

Porcine reproductive and respiratory syndrome (PRRS) virus (PRRSV) impairs local pulmonary immune responses by damaging the mucociliary transport system, impairing the function of porcine alveolar macrophages andinducing apoptosis of immune cells. An imbalance between pro- and anti-inflammatory cytokines, including tumour necrosis factor-α and interleukin-10, in PRRS may impair the immune response of the lung. Pulmonary macrophage subpopulations have a range of susceptibilities to different PRRSV strains and different capacities to express cytokines. Infection with PRRSV decreases the bactericidal activity of macrophages, which increases susceptibility to secondary bacterial infections. PRRSV infection is associated with an increase in concentrations of haptoglobin, which may interact with the virus receptor (CD163) and induce the synthesis of anti-inflammatory mediators. The balance between pro- and anti-inflammatory cytokines modulates the expression of CD163, which may affect the pathogenicity and replication of the virus in different tissues. With the emergence of highly pathogenic PRRSV, there is a need for more information on the immunopathogenesis of different strains of PRRS, particularly to develop more effective vaccines.

Copyright © 2012 Elsevier Ltd. All rights reserved.

Gomez Laguna J, Salguero F J, PallarÃs F J, Carrasco L. Immunopathogenesis of porcine reproductive and respiratory syndrome in the respiratory tract of pigs. The veterinary journal 2012 [in press].

Comparison of PCR assays for PRRSv detection using different sample types (semen, oral fluids, serum, blood swabs)

Abstract

The aims of this study were to compare three commercial porcine reproductive and respiratory syndrome virus (PRRSV) real-time RT-PCR assays for detection of genetically diverse PRRSV isolates in serum, semen, blood swabs, and oral fluids collected from experimentally-infected boars, and to evaluate the effects of sample pooling. Six groups of 3 boars negative for PRRSV were each inoculated with one of six PRRSV isolates (sharing 55-99% nucleotide sequence identity in ORF5). Samples were collected on days post-inoculation (dpi) -2, 1, 3, 5, 7, 14 and 21 and tested by one of three commercially available real-time RT-PCR assays (AB, TC, AD). At dpi 1, all assays detected at least one positive sample in each group. The highest detection rates were on dpi 3 and dpi 5. Between dpi 1 and 7, serum samples had the highest detection rate (90%) with 100% agreement between tests, followed by blood swabs (Kappa = 0.97) and semen (Kappa = 0.80). Oral fluids had the lowest detection rates (AB: 55%; TC: 41%; AD: 46%) and the highest disagreement between kits (Kappa = 0.63). Pools of five samples did not reduce the detection rates if there was one positive sample with a high amount of viral RNA in the pool. Serum and blood swab samples had shorter turn-around times for RNA extraction. The AB assay had a 1.6 times shorter PCR reaction time. In summary, serum and blood swabs had the best performance with highest detection rates and agreement between assays and shortest turn-around time.

PMID:

 

23224085

 

[PubMed - as supplied by publisher]

Gerber PF, O'Neill K, Owolodun O, Wang C, Harmon K, Zhang J, Halbur PG, Zhou L, Meng XJ, Opriessnig T. Comparison of commercial real-time RT-PCR assays for reliable, early and rapid detection of heterologous strains of porcine reproductive and respiratory syndrome virus (PRRSV) in experimentally infected or negative boars using different sample types (semen, oral fluids, serum, blood swabs). 2012. Journal of clinical microbiology [accepted].

Reproductive parameters following a PRRS outbreak where a whole-herd PRRS MLV vaccination strategy was instituted post-outbreak

Abstract

This study assessed the effect of whole-herd porcine reproductive and respiratory syndrome (PRRS) modified-live virus (MLV) vaccination on herd-level reproductive performance, PRRS virus (PRRSV) viremia, and antibody in a subset of females in a 1,200-sow commercial herd in Thailand. Following a PRRSV outbreak, the entire herd was vaccinated with PRRS MLV twice at 3-week intervals and at 3-month intervals, thereafter. Reproductive performance data over a 3-year period were available for analysis. Serum samples were collected before and after vaccination and tested by PRRSV ELISA and reverse transcription-polymerase chain reaction. Vaccination was statistically associated with a lower abortion rate (1.4 vs. 1.6 %), farrowing rate (83.8 vs. 90.0 %), total born (10.6 vs. 11.4 piglets/litter), liveborn (10.0 vs. 10.3 piglets/litter), stillbirths (4.6 vs. 7.0 %), mummies (0.7 vs. 1.6 %), and a higher return rate (11.3 vs. 5.9 %) when compared with the period before the PRRSV outbreak. Pregnant females vaccinated during early gestation farrowed fewer liveborn and more mummies than the comparison group, whereas females vaccinated during late gestation had a lower farrowing rate. In this herd, PRRS whole-herd vaccination had neutral, positive, and negative effects on reproductive performance. Thus, the decision to implement whole-herd vaccination should be balanced between the benefits derived from reproductive performance improvements, e.g., fewer abortions, stillborn piglets, and mummified fetuses, and the effect of vaccination on pregnant females.

Olanratmanee E, Nuntawan Na Ayudhya S, Thanawongnuwech R, Kunavongkrit A, Tummaruk P. Reproductive parameters following a PRRS outbreak where a whole-herd PRRS MLV vaccination strategy was instituted post-outbreak. Tropical animal health and production 2012 [in press].

ORF 5 vs whole genome sequencing for PRRSv

For epidemiological investigations, ORF-5 sequence has been the standard to differentiate PRRSv isolates. In the field people have used different cut offs to differentiate viruses (related vs non-related), the most common being to consider that isolates with 97 to 99% ORF 5 nucleotide similarity (within a year) to be related (Christopher-Hennings et al., JSHAP 2002; Murtaugh, Leman 2012).

However, studies comparing ORF5 sequences have failed to identify RNA segments correlated with virulence. Therefore, some PRRSv-researchers are now studying the whole genome (ORFs 1 to 7) to try to find "the million dollar answer", that is, what makes one isolate relatively avirulent and other isolates "highly pathogenic".

Some examples of PRRSv whole-genome studies that came out this week:

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J Virol. 2012 Dec;86(24):13883-4. doi: 10.1128/JVI.02731-12.

Complete genome sequence of a moderately pathogenic porcine reproductive and respiratory syndrome virus variant strain.

Du Y, Lu Y, Qi J, Wu J, Wang G, Wang J.

Source

Shandong Key Laboratory of Animal Disease Control and Breeding, Institute of Animal Science and Veterinary Medicine, Shandong Academy of Agricultural Sciences, Jinan, China.

Abstract

Porcine reproductive and respiratory syndrome (PRRS) has become one of the most economically important diseases to the global pork industry. The etiological agent is the PRRS virus (PRRSV). In the spring of 2006, a highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) appeared in China and caused heavy economic losses. Here we report the complete genomic sequence of a novel PRRSV variant with 174 amino acid deletions in the nonstructural protein 2 (nsp2) gene.

PMID:

 

23166276

 

[PubMed - in process]

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J Virol. 2012 Dec;86(24):13882. doi: 10.1128/JVI.02729-12.

Complete Genome Sequence of Porcine Reproductive and Respiratory Syndrome Virus Strain ZCYZ Isolated from Hybrid Wild Boars.

Wu J, Liu S, Du Y, Gao Y, Wang G, Wang J.

Source

Shandong Key Lab of Animal Disease Control and Breeding, Shandong Academy of Agricultural Sciences, Jinan, People's Republic of China.

Abstract

A serologic investigation of porcine reproductive and respiratory syndrome virus (PRRSV) in hybrid wild boar herds was conducted during 2008-2009. PRRSV isolates with novel genetic markers were recovered. Experimental infection of pigs indicated that hybrid wild boars are involved in the epidemiology of PRRSV.

PMID:

 

23166275

 

[PubMed - in process]

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J Virol. 2012 Dec;86(24):13863-4. doi: 10.1128/JVI.02642-12.

Complete Genome Sequence of a Highly Pathogenic Porcine Reproductive and Respiratory Syndrome Virus NM1 Strain from Northern China.

Li Z, Leng X, Qi Q, Wang F, Wen Y, Tan B, He Y, Xia M, Lu W, Chen L, Cheng S, Wu H.

Source

Division of Zoonoses, Institute of Special Economic Animal and Plant Sciences, Chinese Academy of Agricultural Sciences, Jilin, China.

Abstract

NM1 is a highly pathogenic North American-type porcine reproductive and respiratory syndrome virus (PRRSV). The complete genome sequence shows that NM1 shares high sequence identity (99.2 to 99.4%) to other HP-PRRSV isolates, containing two discontinuous deletions, a 1-amino-acid deletion at position 481 and a 29-amino-acid deletion at positions 533 to 651, in nonstructural protein 2.

PMID:

 

23166263

 

[PubMed - in process]

Investigation of strategies for the introduction and transportation of replacement gilts

ABSTRACT:

BACKGROUND: Porcine reproductive and respiratory syndrome (PRRS) is of major concern to the swine industry; infection with the virus can lead to production losses, morbidity, and mortality within swine operations. Biosecurity practices related to the management of replacement animals are important for the prevention and control of the PRRS virus, as well as other diseases. The objectives of this study were: (i) to describe individual biosecurity practices related to the introduction and transportation of replacement gilts on southern Ontario sow farms, and (ii) to understand patterns in the implementation of these practices. The second objective was accomplished using multiple correspondence analysis (MCA), which allows visualization of the relationships between individual practices and provides information about which practices frequently occur together, and which practices rarely occur together. These patterns constitute strategies for the implementation of biosecurity practices related to the introduction and transportation of replacement gilts. Data were collected using version 2 of the Production Animal Disease Risk Assessment Program's survey for the breeding herd. Two subsets of variables were retained for analysis; one subset pertained to how replacements were managed upon arrival to the farm, and the other pertained to the transportation of genetic animals.

RESULTS:

For both subsets of variables, the results of the MCA procedure were similar; in both solutions the 1st dimension separated herds that were closed with respect to replacement animals from herds that were open, and the 2nd dimension described how open herds managed replacements. The most interesting finding of this study was that, in some cases where a risky practice was being implemented, it was closely associated with other biosecurity practices that may mitigate that risk.

CONCLUSIONS:

The findings from this approach suggest that one cannot always examine biosecurity on a variable-by-variable basis. Even if a practice that is generally considered high-risk is being implemented, it may be balanced by other practices that mitigate that risk. Thus, the overall biosecurity strategy on a farm must be considered instead of only examining the implementation of individual practices.

PMID:

 

23140357

 

[PubMed - as supplied by publisher]

Bottoms K, Poljak Z, Dewey C, Deardon R, Holtkamp D, Friendship R. Investigation of strategies for the introduction and transportation of replacement gilts on southern Ontario sow farms. BMC veterinary research 2012;8(1):217-217.

PRRSv diversity in Romania

Abstract

Porcine reproductive and respiratory syndrome (PRRS) is a disease produced by the (PRRS) virus, characterized by endemic evolution in the majority of countries, which remains in actuality being a permanent threat to health and economic free farms, as well as for those infected. The aim of this study was to evaluate the genetic diversity of Romanian PRRSV isolates from the four most important pig farms in Romania by comparing the nucleotide sequences obtained for ORF5 and ORF7 with a wide range of sequences from GenBank belonging to the main types of PRRSV; the type 1. Eighteen different sequences were obtained for ORF5 gene and 10 for ORF7 gene. One Romanian isolate (Rom3) was found in three of the four different investigated farms. The phylogenetic analysis revealed that the Romanian PRRSV nucleotide sequences clustered in three groups within the subtype 1 of the virus. The analysis of amino acid sequences evidenced for GP5 and N-nucleocapsid proteins confirmed that the Romanian virus belonged to type 1.

PMID:

 

23109899

 

[PubMed - in process]

Zaulet M, Gurau M R, Petrovan V, Buburuzan L. Genetic diversity characterization of porcine reproductive and respiratory syndrome virus isolates in Romania, based on phylogenetic analysis. International journal of molecular sciences 2012;13(9):12046-12061.