Porcine Reproductive And Respiratory Syndrome Vaccine Research Articles

Gambaran Hematologi Darah Pasca Vaksinasi Porcine Reproductive and Respiratory Syndrome (PRRS) pada Ternak Babi di Kabupaten Kupang

The potential for expanding pig farming, particularly with native pigs, in East Nusa Tenggara (NTT) Province is significant due to the predominant non-Muslim population in NTT who utilise pigs in traditional and religious ceremonies. However, the high number of pigs in Kupang Regency and conventional farming practices can elevate the likelihood of infections like Porcine Reproductive and Respiratory Syndrome, known as PRRS. Porcine reproductive and respiratory syndrome (PRRS), caused by the PRRS virus (PRRSV), is a significant disease in the pig farming sector. The porcine reproductive and respiratory syndrome virus is highly contagious within pig herds. It can spread through direct contact or contaminated aerosols. Vaccines have been used to limit the disease’s transmission, despite often being considered ineffective. This study analyses the variations in blood haematological parameters before and after PRRS immunisation, including RBC, HGB, PCV, MCV, MCH, MCHC, and WBC. Fifteen pigs were included in the sample. Sampling was conducted two times from the same pigs: before PRRS vaccination and one month post-immunization. SPSS was used for the data analysis. A statistical study using SPSS showed no significant difference in blood hematology following the PRRS vaccination.

Current Status of Vaccines for Porcine Reproductive and Respiratory Syndrome: Interferon Response, Immunological Overview, and Future Prospects.

Porcine reproductive and respiratory syndrome (PRRS) remains a formidable challenge for the global pig industry. Caused by PRRS virus (PRRSV), this disease primarily affects porcine reproductive and respiratory systems, undermining effective host interferon and other immune responses, resulting in vaccine ineffectiveness. In the absence of specific antiviral treatments for PRRSV, vaccines play a crucial role in managing the disease. The current market features a range of vaccine technologies, including live, inactivated, subunit, DNA, and vector vaccines, but only modified live virus (MLV) and killed virus (KV) vaccines are commercially available for PRRS control. Live vaccines are promoted for their enhanced protective effectiveness, although their ability to provide cross-protection is modest. On the other hand, inactivated vaccines are emphasized for their safety profile but are limited in their protective efficacy. This review updates the current knowledge on PRRS vaccines' interactions with the host interferon system, and other immunological aspects, to assess their current status and evaluate advents in PRRSV vaccine development. It presents the strengths and weaknesses of both live attenuated and inactivated vaccines in the prevention and management of PRRS, aiming to inspire the development of innovative strategies and technologies for the next generation of PRRS vaccines.

Mass Spectrometry-Based Proteomic Analysis of Potential Host Proteins Interacting with GP5 in PRRSV-Infected PAMs.

Porcine reproductive and respiratory syndrome virus (PRRSV) is a typical immunosuppressive virus causing a large economic impact on the swine industry. The structural protein GP5 of PRRSV plays a pivotal role in its pathogenicity and immune evasion. Virus-host interactions play a crucial part in viral replication and immune escape. Therefore, understanding the interactions between GP5 and host proteins are significant for porcine reproductive and respiratory syndrome (PRRS) control. However, the interaction network between GP5 and host proteins in primary porcine alveolar macrophages (PAMs) has not been reported. In this study, 709 GP5-interacting host proteins were identified in primary PAMs by immunoprecipitation coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Bioinformatics analysis revealed that these proteins were involved in multiple cellular processes, such as translation, protein transport, and protein stabilization. Subsequently, immunoprecipitation and immunofluorescence assay confirmed that GP5 could interact with antigen processing and presentation pathways related proteins. Finally, we found that GP5 may be a key protein that inhibits the antigen processing and presentation pathway during PRRSV infection. The novel host proteins identified in this study will be the candidates for studying the biological functions of GP5, which will provide new insights into PRRS prevention and vaccine development.

Production of a chimeric porcine reproductive and respiratory syndrome virus (PRRSV)-2 vaccine using a lab-scale packed-bed bioreactor CelCradle

BackgroundWe developed a MARC-145 cell culture and porcine reproductive and respiratory syndrome (PRRS) vaccine production using a novel CelCradle bioreactor. CelCradle is a packed-bed bioreactor capable of both batch and perfusion culture, and the operating parameters are easy to optimize.ResultsIn this study, CelCradle reached a maximum cell density of 8.94 × 105 cells/mL at 5 days post-seeding when seeded at 8.60 × 104 cells/mL (doubling time = 35.52 h). Inoculation of PRRS vaccine candidate, K418DM1.1, was performed at a multiplicity of infection (MOI) of 0.01 at 5 days post-seeding, which resulted in a high viral titer of 2.04 × 108 TCID50/mL and total viral load of 1.02 × 1011 TCID50/500 mL at 2 days post-infection (dpi). The multilayer cultivation system, BioFactory culture, yielded a higher doubling time (37.14 h) and lower viral titer (i.e., 8.15 × 107 TCID50/mL) compared to the CelCradle culture. Thus, the culture medium productivity of the CelCradle culture was 2-fold higher than that of the BioFactory culture. In the animal experiment, the CelCradle-produced vaccine induced high levels of neutralizing antibodies and effectively protected pigs against homologous challenge, as shown by the significantly lower levels of viremia at 1- and 7-days post-challenge (dpc) compared to the non-vaccinated pigs.ConclusionsOverall, this study demonstrates that the CelCradle system is an economical platform for PRRS vaccine production.

Research Progress on the Development of Porcine Reproductive and Respiratory Syndrome Vaccines.

Porcine reproductive and respiratory syndrome (PRRS) is a highly contagious disease in the pig industry, but its pathogenesis is not yet fully understood. The disease is caused by the PRRS virus (PRRSV), which primarily infects porcine alveolar macrophages and disrupts the immune system. Unfortunately, there is no specific drug to cure PRRS, so vaccination is crucial for controlling the disease. There are various types of single and combined vaccines available, including live, inactivated, subunit, DNA, and vector vaccines. Among them, live vaccines provide better protection, but cross-protection is weak. Inactivated vaccines are safe but have poor immune efficacy. Subunit vaccines can be used in the third trimester of pregnancy, and DNA vaccines can enhance the protective effect of live vaccines. However, vector vaccines only confer partial protection and have not been widely used in practice. A PRRS vaccine that meets new-generation international standards is still needed. This manuscript provides a comprehensive review of the advantages, disadvantages, and applicability of live-attenuated, inactivated, subunit, live vector, DNA, gene-deletion, synthetic peptide, virus-like particle, and other types of vaccines for the prevention and control of PRRS. The aim is to provide a theoretical basis for vaccine research and development.

Effect of the host genotype at a Porcine Reproductive and Respiratory Syndrome (PRRS) resistance marker on evolution of the modified-live PRRS vaccine virus in pigs

Porcine reproductive and respiratory syndrome; Porcine reproductive and respiratory syndrome virus; PRRS; Whole genome sequencing; Quasispecies; WUR allele.

Associations of natural variation in the CD163 and other candidate genes on host response of nursery pigs to porcine reproductive and respiratory syndrome virus infection

Pigs with complete resistance to porcine reproductive and respiratory syndrome (PRRS) virus (PRRSV) have been produced by genetically knocking out the CD163 gene that encodes a receptor of the PRRSV for entry into macrophages. The objectives of this study were to evaluate associations of naturally occurring single nucleotide polymorphisms (SNPs) in the CD163 gene and in three other candidate genes (CD169, RGS16, and TRAF1) with host response to PRRSV-only infection and to PRRS vaccination and PRRSV/porcine circovirus 2b (PCV2b) coinfection. SNPs in the CD163 gene were not included on SNP genotyping panels that were used for previous genome-wide association analyses of these data. An additional objective was to identify the potential genetic interaction of variants at these four candidate genes with a mutation in the GBP5 gene that was previously identified to be associated with host response to PRRSV infection. Finally, the association of SNPs with expression level of the nearby gene was tested. Several SNPs in the CD163, CD169, and RGS16 genes were significantly associated with host response under PRRSV-only and/or PRRSV/PCV2b coinfection. The effects of all SNPs that were significant in the PRRSV-only infection trials depend on genetic background. The effects of some SNPs in the CD163, CD169, and RGS16 genes depend on genotype at the putative causative mutation in the GBP5 gene, which indicates a potential biological interaction of these genes with GBP5. In addition, genome-wide association results for the PRRSV-only infection trials revealed that SNPs located in the CDK5RAP2 or MEGF9 genes, near the TRAF1 gene, had suggestive effects on PRRS viral load, which indicates that these SNPs might contribute to PRRSV neuropathogenesis. In conclusion, natural genetic variants in the CD163, CD169, and RGS16 genes are associated with resistance to PRRSV and/or PCV2b infection and appear to interact with the resistance quantitative trait locus in the GBP5 gene. The identified SNPs can be used to select for increased natural resistance to PRRSV and/or PRRSV-PCV2b coinfection.

Immune efficacy of a candidate porcine reproductive and respiratory syndrome vaccine rHN-NP49 administered by a Needle-free intradermal delivery system in comparison with intramuscular injection

Porcine reproductive and respiratory syndrome (PRRS) is one of the major drivers of economic loss in the swine industry worldwide. In commercial pig production, vaccination is the first option in an attempt to control infectious diseases. Pigs are therefore often immunized with different vaccines, and almost all of them are delivered via the intramuscular (IM) route. However, the IM injection may result in physical damage, stress reactions, and is labor demanding. An alternative route is urgently needed to reduce the disadvantages of conventional vaccination. In this study, a needle-free intradermal (ID) delivery system was evaluated for delivering a live PRRS vaccine as compared with the traditional needle-syringe method. Fifty-two 4-week-old piglets were divided into six groups: piglets in groups A-C were immunized using ID delivery system with 104, 105 and 106 TCID50 of PRRS candidate vaccine strain rHN-NP49, respectively; piglets in group D were immunized IM with 105 TCID50 of rHN-NP49; and group E and F were used as challenge and control groups, respectively. At 28 days post vaccination, piglets in group A to E were challenged with a lethal dose of highly-pathogenic PRRSV. Similar results were found in viremia and antibody response among the ID and IM groups during the immunization stage. After challenge, similar results were found in average body weight gain, viral shedding, serum viral load, and clinical score among the immunization groups, with a higher protection ratio in the ID group compared with IM group with the same immunization dose. These results demonstrated that the ID delivery system could provide similar or even better protection compared with IM route, and could be an effective route for PRRS vaccination.

Intramuscular vs. Intradermic Needle-Free Vaccination in Piglets: Relevance for Animal Welfare Based on an Aversion Learning Test and Vocalizations.

The aim of the present study was to compare intramuscular injection with a needle and intradermic needle-free vaccinations against porcine reproductive and respiratory syndrome (PRRS) in piglets at 28 days old by studying behavioral and physiological reactions. A total of 72 piglets divided into 2 sex-balanced batches were assessed. Within each batch, the piglets were divided into three treatments, which were Hipradermic (0.2 ml of UNISTRAIN® PRRS vaccine administered with an intradermic needle-free device), Intramuscular (IM, 2.0 ml of vaccine), and Control (not vaccinated). Before the vaccination, the piglets were trained to cross a 4-m-long raceway to perform an aversion learning test. The day of vaccination, the time taken to cross the raceway was registered for each piglet at different times: prior to the vaccination and 10 min, 2, 24, 48, and 72 h after the vaccination, to measure variations in these times as signs of aversion to the vaccination process. Vocalizations, as potential signs of pain, were recorded as well at the end of this raceway to analyze their frequency (Hz), duration, and level of pressure (dB) at the moment of vaccination. Salivary cortisol, as a sign of the HPA-axis activity, was assessed 10 min after the vaccination. In addition, activity budgets, local reaction to the vaccine, and serological titer were also considered in the study. Ten minutes after the vaccination, the IM piglets took longer (p < 0.001) to cross the raceway than did the Hipradermic and Control piglets. Vocalizations were significantly different between the three treatments: the Control piglets produced vocalizations with the lowest frequency (p < 0.001) and level of pressure (p < 0.001), and IM with the highest, with Hipradermic in a significant intermediate position (p < 0.001). Accordingly, the day of the vaccination, IM and Hipradermic animals were lying on the side of the vaccine administration a greater proportion of time than were the Control piglets (10, 11, and 6%, respectively; p = 0.027). Salivary cortisol was not significantly different between treatments. The serum titer of antibodies against the PRRS was higher (p < 0.001) in both vaccinated treatments in comparison to the Control piglets. It is concluded that the Hipradermic needle-free vaccination may result in a less aversive experience in piglets than did intramuscular vaccination.

Genetic Variability of PRRSV Vaccine Strains Used in the National Eradication Programme, Hungary.

Porcine reproductive and respiratory syndrome (PRRS) is a globally spread, highly infectious viral disease. Live, attenuated vaccines against PRRS virus (PRRSV) decrease virus excretion and evoke protective immunity reducing the economic damage caused by the disease. In a longitudinal molecular epidemiological study accompanying ongoing national eradication programme we evaluated the suitability of PRRSV ORF5 and ORF7 sequences to identify possible field strains of vaccine-origin. In total, 2342 ORF5 sequences and 478 ORF7 sequences were analysed. Vaccine strains were identified by sequence identity values and phylogenetic network analysis. Strains that shared greater than 98% nucleotide identity within ORF5 and/or ORF7 were considered to have originated from vaccine. A total of 882 (37.6%) ORF5 and 88 (18.4%) ORF7 sequences met these criteria. In detail, 618, 179 and 35 ORF5 and 51, 29 and 8 ORF7 sequences were related to Porcilis PRRS vaccine, Unistrain PRRS vaccine, and ReproCyc PRRS EU vaccine, respectively. Data showed that the Porcilis vaccine was genetically more stable. Whereas, the variability of the Unistrain and the ReproCyc strains was significantly higher. Given that ORF7 shares, in some instances, complete identity between a particular vaccine strain and some historic variants of field PRRSV strains, care must be taken when evaluating vaccine relatedness of a field isolate based on the ORF7. On the contrary, ORF5 sequences were more suitable to predict the vaccine origin making a distinction more robustly between field and vaccine strains. We conclude that ORF5 based molecular epidemiological studies support more efficiently the ongoing PRRS eradication programmes. The conclusions presented in this large-scale PRRS molecular epidemiological study provides a framework for future eradication programmes planned in other countries.

Porcine Reproductive and Respiratory Syndrome Modified Live Virus Vaccine: A "Leaky" Vaccine with Debatable Efficacy and Safety.

Porcine reproductive and respiratory syndrome (PRRS) caused by the PRRS virus (PRRSV) is one of the most economically important diseases, that has significantly impacted the global pork industry for over three decades, since it was first recognized in the United States in the late 1980s. Attributed to the PRRSV extensive genetic and antigenic variation and rapid mutability and evolution, nearly worldwide epidemics have been sustained by a set of emerging and re-emerging virus strains. Since the first modified live virus (MLV) vaccine was commercially available, it has been widely used for more than 20 years, for preventing and controlling PRRS. On the one hand, MLV can induce a protective immune response against homologous viruses by lightening the clinical signs of pigs and reducing the virus transmission in the affected herd, as well as helping to cost-effectively increase the production performance on pig farms affected by heterologous viruses. On the other hand, MLV can still replicate in the host, inducing viremia and virus shedding, and it fails to confer sterilizing immunity against PRRSV infection, that may accelerate viral mutation or recombination to adapt the host and to escape from the immune response, raising the risk of reversion to virulence. The unsatisfied heterologous cross-protection and safety issue of MLV are two debatable characterizations, which raise the concerns that whether it is necessary or valuable to use this leaky vaccine to protect the field viruses with a high probability of being heterologous. To provide better insights into the immune protection and safety related to MLV, recent advances and opinions on PRRSV attenuation, protection efficacy, immunosuppression, recombination, and reversion to virulence are reviewed here, hoping to give a more comprehensive recognition on MLV and to motivate scientific inspiration on novel strategies and approaches of developing the next generation of PRRS vaccine.

A chimeric porcine reproductive and respiratory syndrome virus (PRRSV)-2 vaccine is safe under international guidelines and effective both in experimental and field conditions

Vaccination is currently the most effective strategy to control porcine reproductive and respiratory syndrome (PRRS). New-generation PRRS vaccines are required to be safe and broadly cross-protective. We have recently created the chimeric PRRS virus K418DM which proved to be a good vaccine candidate under field conditions. In the present study, we designed safety and efficacy tests under experimental and field conditions for further evaluation of K418DM1.1, a plaque-purified K418DM. In the homologous challenge study, K418DM1.1 induced high serum virus neutralization (SVN) antibody titers (i.e., 4.2 log2 ± 1.7) at 21 days post-challenge (dpc) and provided protection as demonstrated by the significantly lower levels of viremia at 3 and 7 dpc and significantly lower microscopic lung lesion scores compared to the unvaccinated group. K418DM1.1 was also protective in the heterologous challenge study, with vaccinated pigs showing significantly lower levels of viremia at 14 dpc compared to the unvaccinated pigs. A field study was performed to evaluate the efficacy of K418DM1.1 against heterologous exposure and vaccinated pigs presented significantly lower viremia than unvaccinated pigs. According to the safety test for the examination of virulence reversion, no infectivity was observed in tissue homogenate filtrate both in the vaccinated and comingled groups. Thus, the risk of virulence, as well as transmission, appeared negligible. These overall results indicate that K418DM1.1 is a good vaccine candidate based on its safety and protective efficacy.

20 Vaginal microbiome composition is associated with sow longevity

Abstract The vaginal microbiome of gilts vaccinated for porcine reproductive and respiratory syndrome (PRRS) has been previously associated with first-parity reproductive performance in absence of PRRS outbreak. However, associations using multiparous sows have not been investigated. The objective of this study was to associate the vaginal microbiota of PRRS-vaccinated gilts with longevity. Vaginal swabs from 251 commercial F1 gilts (Landrace/Large-White) were collected on days 4 and 52 after PRRS vaccination (dpv) for 16S rRNA sequencing. Sequences were clustered into operational taxonomic unit (OTU). Sows were assigned to one of four groups according to the maximum parity reached (number of animals): without parity (13), first-parity (45), second-parity (47), and 3 or more parities (146). A negative binomial mixed model including fixed effects of group, dpv, group*dpv, and collection age (covariate), and random effect of animal, was used to identify OTUs with differential abundance. The false discovery rate method was used for multiple test correction. Canonical discriminant analysis (CDA) was performed to classify animals into the four parity groups by including significant OTUs in stepwise selection (P &amp;lt; 0.05) using the whole data. A leave-one-out-cross-validation was used to assess the predictive ability of OTUs to correctly classify animals into the parity groups. Abundance of five and four OTUs was associated (q &amp;lt; 0.05) with group and with group*dpv (q &amp;lt; 0.05), respectively. In the CDA analysis, 220 OTUs identified in the vaginal microbiome were included (P &amp;lt; 0.05). The first and second canonical variables explained 96.6 and 3.4% of the variation, respectively. All animals were correctly classified into their respective parity groups. This study indicates that the vaginal microbiome composition of gilts collected after PRRS-vaccination may be used to predict longevity in commercial sow herds. This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brazil (Capes) – Finance Code 001.

15 Host genetics of antibody response to PRRS vaccination and infection in growing pigs

Abstract Antibody response to Porcine Reproductive and Respiratory Syndrome (PRRS) vaccination and infection has been shown to be highly heritable in gilts and sows. This trait, measured as sample-to-positive (S/P) ratio, has been proposed as a selection tool for improved reproductive performance in sows. However, this novel trait has not yet been explored in growing pigs. Therefore, the objective of this study was to estimate genetic parameters for S/P in PRRS-challenged nursery pigs. A total of 854 PRRS-naïve crossbred barrows and gilts (51.9±4.8 d and 17.8±4.6 kg) were randomly allocated to 54 pens in two rooms and vaccinated with a modified live virus PRRS vaccine. Twenty-eight days later (d0), all animals were experimentally inoculated with a highly virulent strain of PRRS virus. Body weight (BW), S/P, and clinical signs of disease were recorded at this time and again at d13. Average daily gain (ADG) was calculated and used in combination with clinical signs to create two distinct groups, robust (R) and susceptible (S), with ~230 animals each. At d42, S/P was measured only in these classified animals. Genetic parameters and effect of classification were estimated for S/P for each collection day. Heritability estimates for S/P were 0.07±0.06, 0.52±0.09, and 0.43±0.28, for d0, d13, and d42, respectively. Genetic correlation estimates were high between collection days, ranging from 0.91±0.31 (d0 and d42) to 0.98±0.03 (d13 and d42). There was an effect of classification for S/P only at d13 (P=0.024), with R showing greater S/P (1.7±0.03) than S (1.64±0.03). These results indicate that, in PRRS-challenged growing pigs, S/P is highly heritable at later collection days, and differences in S/P exist between robust and susceptible animals.

93 Genomic basis of antibody response to porcine reproductive and respiratory syndrome virus vaccination

Abstract Antibody (Ab) response to natural infection with porcine reproductive and respiratory syndrome (PRRS) virus has been shown to be highly heritable (~0.40), to be genetically correlated with farrowing performance in PRRSV-infected sows, be controlled by two major QTL on chromosome 7, among others, and have moderate genomic prediction accuracy. However, waiting for PRRS outbreaks to occur to collect data limits the use of Ab response to select for increased PRRS resilience. Thus, we investigated the genomic basis of Ab response to PRRS vaccination with a modified live PRRSV vaccine as a strategy to generate data for this purpose. Nine hundred and six commercial F1 replacement gilts (189±16 days old) were vaccinated with a commercial PRRS modified live virus vaccine. Blood samples were collected 52 days after vaccination to measure Ab response, as sample-to-positive (S/P) ratio using a commercial ELISA, and for SNP genotyping (~50K). BayesC0 was used to estimate heritability for S/P ratio using in a model with contemporary group (CG) as fixed effect and SNP effects as random. Genome-wide association study and genomic prediction for S/P ratio were performed with BayesB (Pi=0.99). For genomic prediction, a three-fold cross-validation was used, in which each CG (n=3) was used as validation dataset. Accuracy of genomic prediction was defined as the correlation between genomic estimated breeding values and phenotypes adjusted for estimates of fixed effects, weighed by the number of individuals in the validation dataset. Heritability of S/P was moderate (0.35±0.04). A QTL was identified on chromosome 7 (25 Mb) explaining ~28% of the genetic variance. Accuracy of genomic prediction was fairly high (0.60±0.15). This is the first study describing the genomic basis of Ab response to PRRS vaccination with modified-live virus vaccine. Additional work is needed to evaluate the genetic correlation of Ab response to vaccination with resilience traits in pigs.

27 Genomic relationship between antibody response to porcine reproductive and respiratory syndrome virus vaccination and reproductive performance in commercial sows

Abstract Antibody response, measured as sample-to-positive ratio (S/P), to porcine reproductive and respiratory syndrome (PRRS) after PRRS outbreaks has been proposed as an indicator trait to improve reproductive performance in PRRS-infected sows. However, waiting for a PRRS outbreak to occur and having different relationships in healthy pigs may limit the use of this trait. Thus, we proposed to investigate if this relationship also occurs between S/P to PRRS vaccination and reproductive performance in sows without exposure to PRRS. Nine hundred six F1 replacement gilts (139□17 days old) from two commercial farms were vaccinated with a commercial modified live PRRS virus vaccine. Blood samples were collected at 52 days after vaccination to measure S/P to PRRS and SNP genotyping. Reproductive performance included: number born alive (NBA), number of piglets weaned, number born mummified (MUM), number stillborn (NSB), and pre-weaning mortality (PWM) at parities (P) 1 to 3. Average performance was calculated for each trait per sow per year (PSY). Farrowing rate and age at first service were also analyzed. BayesC0 was used to estimate genetic correlations between S/P and reproductive performance. Bivariate genome-wide association studies of antibody response and reproductive traits were performed using BayesB. High genetic correlations between S/P and farrowing performance were identified for NBA_P1 (0.61±0.16), PWM_P2 (-0.64±0.15), PWM_P2 (-0.63±0.20), NSB_P3 (-0.84±0.05), MUM_P3 (-0.83±0.11), and NSB_PSY (-0.90±0.05). A QTL was identified on chromosome 7 (MHC region) for these reproductive traits and for S/P, explaining from 1.2% (PWM_P2) to 22.4% (S/P) of the genetic variance. SNP H3GA0020505 explained most of the variance in this region for these traits. Heterozygote animals for this SNP had overall better performance: greater S/P (P = 0.001), greater (P = 0.06) NBA_P1, and lesser (P = 0.06) MUM_P3 than other genotypes. These results suggest that antibody response to PRRS vaccination may be used as a genetic indicator to improve reproductive performance in commercial pigs.

Modeling Economic Effects of Vaccination Against Porcine Reproductive and Respiratory Syndrome: Impact of Vaccination Effectiveness, Vaccine Price, and Vaccination Coverage.

Porcine reproductive and respiratory syndrome (PRRS) causes substantial financial losses in pig farms and economic losses to societies worldwide. Vaccination against PRRS virus (PRRSV) is a common intervention in affected farms. The aim of this study was to assess the economic impact and profitability of potential new PRRS vaccines with improved efficacy at animal, herd, and national level. Two vaccination strategies were modeled; (i) mass vaccination of sows only (MS) and (ii) mass vaccination of sows and vaccination of piglets (MSP), comprising different scenarios of vaccine effectiveness, vaccine price, and vaccination coverage. A farrow-to-finish farm with 1,000 working sows from a pig-dense region in Germany served as an example farm. Financial benefits were obtained from gross margin analyses and were defined as difference in gross margin between a PRRSV-infected farm without vaccination (baseline) and with vaccination (intervention). Financial benefits were highest if both sows and piglets (MSP) were vaccinated. In these scenarios, median annual net benefits per working sow ranged from €170 to 340. If sows only were vaccinated (MS), estimated benefits attributable to vaccination were between €148 and 270. Decisive variables for the estimation of national level benefits were the number of farmers switching from existing to a better protecting vaccine, the number of previously non-vaccinating herds adopting the new vaccine, and the effectiveness of the new vaccine relative to those already available. Benefits were greatest when the new vaccine was adopted by previously non-vaccinating herds. The analyses showed that vaccination against PRRS was beneficial for all modeled scenarios. The magnitude of benefits derived from vaccination was more susceptible to changes in vaccination effectiveness than to vaccine price changes. This study provides evidence to support future vaccine development. The estimates indicate that the introduction of more efficient vaccines might lead to substantial financial benefits, is of socio-economic importance and that new vaccines might significantly contribute to the reduction of disease burden.

The infectious cDNA clone of commercial HP-PRRS JXA1-R-attenuated vaccine can be a potential effective live vaccine vector.

Multiple commercial porcine reproductive and respiratory syndrome (PRRS) modified live vaccines are currently utilized in Chinese swine herds due to the limited cross-protection of vaccines and coexistence of different PRRS viruses. In this study, an infectious cDNA clone of the highly pathogenic PRRS (HP-PRRS) vaccine JXA1-R strain was generated. We successfully rescued the virus from direct in vitro DNA transfection of rJXA1-R clone, which has similar growth kinetics to the parental JXA1-R virus in Marc-145 cells. To further evaluate the potential use of the cloned rJXA1-R virus as a live vector for foreign gene expression, the enhanced green fluorescent protein (EGFP) was inserted between non-structural and structural genes. Our results showed that the dynamic expression of EGFP can be visualized by live cell imaging system during the infection in Marc-145 cells. The availability of our cloned JXA1-R viruses provides a crucial platform to study the fundamental biology of HP-PRRS virus vaccine and also serves as a potential effective vector for developing live vector vaccines against swine pathogens.

Porcine reproductive and respiratory syndrome control in Saxony and Thuringia - Results of 2 voluntary regional programmes in the years 2011-2018

The present study is intended to show the progress of voluntary porcine reproductive and respiratory syndrome (PRRS) control programmes in Thuringia and Saxony as well as to emphasize the importance of confirmation testing in the case of positive findings in unsuspicious herds. In order to present the progress of porcine reproductive and respiratory syndrome virus (PRRSV) elimination, the findings for the years 2011-2018 as well as data on the elimination programme, type and size of the farms, and use of PRRS vaccination were compiled. Each herd was assigned an antibody and PCR status for each year in order to analyze the relationship between status and year. Furthermore, the association between status and herd size as well as the use of PRRS vaccination were investigated. The relevance of confirmation testing is shown by the findings of the herds in the years following PRRSV elimination. In the majority of affected farms in Saxony, depopulation/repopulation was performed in order to eliminate PRRSV. In Thuringia, PRRSV elimination was frequently accomplished during ongoing production. A significant reduction of positive antibody and PCR findings was observed in both federal states during the investigation period. Higher antibody and PCR levels were evident in farms using PRRS vaccination. In the years following PRRSV elimination, positive PRRSV antibody findings occurred in individual PRRSV-unsuspicious farms. These were shown to be false-positive by use of confirmation tests. The proportion of PRRSV-positive herds in a region with low pig density can be reduced by voluntary control programmes with the eradication method playing a subordinate role. The use of vaccination against PRRSV or alternative control measures is to be considered carefully. In the case of positive findings in unsuspicious farms, confirmation testing is warranted in order to rule out any ongoing PRRS outbreak as well as to clarify the farm's status. Voluntary PRRS elimination and maintenance of the status of "PRRSV unsuspicious" is possible even when individual herds in the region do not participate in the control programme.

Evaluation of a type 2 modified live porcine reproductive and respiratory syndrome vaccine against heterologous challenge of a lineage 3 highly virulent isolate in pigs.

Porcine reproductive and respiratory syndrome (PRRS) is one of the most common diseases in the global swine industry. PRRSV is characterized by rapid mutation rates and extensive genetic divergences. It is divided into two genotypes, which are composed of several distinct sub-lineages. The purpose of the present study was to evaluate the cross-protective efficacy of Fostera PRRS MLV, an attenuated lineage 8 strain, against the heterologous challenge of a lineage 3 isolate. Eighteen pigs were randomly divided into mock, MLV and unvaccinated (UnV) groups. The pigs in the MLV group were administered Fostera PRRS vaccine at 3 weeks of age and both the MLV and UnV groups were inoculated with a virulent PRRSV isolate at 7 weeks. Clinically, the MLV group showed a shorter duration and a lower magnitude of respiratory distress than the UnV group. The average days of fever in the MLV group was 3.0 ± 0.5, which was significantly lower than the 6.2 ± 0.5 days of the UnV group (P < 0.001). The average daily weight gains of the mock, MLV and UnV groups were 781 ± 31, 550 ± 44 and 405 ± 26 g/day, respectively, during the post-challenge phase. The pathological examinations revealed that the severity of interstitial pneumonia in the MLV group was milder compared to the UnV group. Furthermore, PRRSV viremia titers in the MLV pigs were consistently lower (101−101.5 genomic copies) than those of the UnV pigs from 4 to 14 DPC. In conclusion, vaccination with Fostera PRRS MLV confers partial cross-protection against heterologous challenge of a virulent lineage 3 PRRSV isolate.