Ability of ELISAs to detect antibodies against porcine respiratory and reproductive syndrome virus in serum of pigs after inactivated vaccination and subsequent challenge: Ability of ELISAs to detect antibodies against porcine respiratory andreproductive syndrome virus in serum of pigs after inactivated vaccination and subsequent challenge

Background: In this study, six enzyme-linked immunosorbent assays (ELISA), intended for routine porcine reproductive and respiratory syndrome virus (PRRSV) herd monitoring, are tested for their ability to detect PRRSV specific antibodies in the serum of pigs after vaccination with an inactivated PRRSV type 1 vaccine and subsequent infection with a highly pathogenic (HP) PRRSV field strain. For this reason, ten piglets (group V) from a PRRSV negative herd were vaccinated twice at the age of 2 and 4 weeks with an inactivated PRRSV vaccine. Ten additional piglets (group N) from the sameherd remained unvaccinated. Three weeks after second vaccination, each of the piglets received an intradermal application of an HP PRRSV field strain. Serum samples were taken before first vaccination as well as before and 3, 7, 10 and 14 days after HP PRRSV application. All serum samples were tested for PRRSV RNA by reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) as well as for PRRSV antibodies with all six study ELISAs. Results: At the beginning of the study (before vaccination), all of the piglets were PRRSV antibody negative with all study ELISAs. They also tested negative for PRRSV RNA measured by RT-qPCR. From day 3 after HP PRRSV application until the end of the study, a viremia was detected by RT-qPCR in all of the piglets. On day 0 (day of HP PRRSV application), nine out of ten piglets of the pre-vaccinated group tested PRRSV antibody positive with one of the tested ELISAs, although with lower S/P values than after infection. On day 10 after HP PRRSV application, all study ELISAs except one had significantly higher S/P or OD values, respectively more positive samples, in group V than in group N. Conclusions: Only one of the tested ELISAs was able to detect reliably PRRSV antibodies in pigs vaccinated with an inactivated PRRSV vaccine. With most of the tested ELISAs, higher S/P values respectively more positive samples after PRRSV infection were seen in the pre-vaccinated group than in the non-vaccinated

Comparison of different commercial ELISAs for detection of antibodies against porcine respiratory and reproductive syndrome virus in serum

Background: In recent years, several new ELISAs for the detection of antibodies against the porcine reproductive and respiratory disease virus (PRRSV) in pig serum have been developed. To interpret the results, specificity and sensitivity data as well as agreement to a reference ELISA must be available. In this study, three commercial ELISAs (INgezim PRRS 2.0 - ELISA II, Priocheck® PRRSV Ab porcine – ELISA III and CIVTEST suis PRRS E/S PLUS - ELISA IV, detecting PRRSV type 1 antibodies) were compared to a standard ELISA (IDEXX PRRS X3 Ab Test - ELISA I). The serum of three pigs vaccinated with an attenuated PRRSV live vaccine (genotype 2) was tested prior to and several times after the vaccination. Furthermore, serum samples of 245 pigs of PRRSV positive herds, 309 pigs of monitored PRRSV negative herds, 256 fatteners of assumed PRRSV negative herds with unknown herd history and 92 wild boars were tested with all four ELISAs. Results: ELISAs II and III were able to detect seroconversion of vaccinated pigs with a similar reliability. According to kappa coefficient, the results showed an almost perfect agreement between ELISA I as reference and ELISA II and III (kappa > 0.8), and substantial agreement between ELISA I and ELISA IV (kappa = 0.71). Sensitivity of ELISA II, III and IV was 96.0%, 100% and 91.5%, respectively. The specificity of the ELISAs determined in samples of monitored PRRSV negative herds was 99.0%, 95.1% and 96.4%, respectively. In assumed negative farms that were not continually monitored, more positive samples were found with ELISA II to IV. The reference ELISA I had a specificity of 100% in this study. Conclusions: All tested ELISAs were able to detect a PRRSV positive herd. The specificity and sensitivity of the tested commercial ELISAs, however, differed. ELISA II had the highest specificity an ELISA III had the highest sensitivity in comparison to the reference ELISA. ELISA IV had a lower sensitivity and specificity than the other ELISAs

Evaluation of the specificity of a commercial ELISA for detection of antibodies against porcine respiratory and reproductive syndrome virus in individual oral fluid of pigs collected in two different ways

Background: The monitoring of infectious diseases like the porcine reproductive and respiratory syndrome (PRRS) using pen-wise oral fluid samples becomes more and more established. The collection of individual oral fluid, which would be useful in the monitoring of PRRSV negative boar studs, is rather difficult. The aim of the study was to test two methods for individual oral fluid collection from pigs and to evaluate the specificity of a commercial ELISA for detection of PRRSV antibodies in these sample matrices. For this reason, 334 serum samples from PRRSV negative pigs (group 1) and 71 serum samples from PRRSV positive pigs (group 2) were tested for PRRSV antibodies with a commercial ELISA. Individual oral fluid was collected with a cotton gauze swab from 311 pigs from group 1 and 39 pigs from group 2. Furthermore, 312 oral fluid samples from group 1 and 67 oral fluid samples from group 2 were taken with a self-drying foam swab (GenoTube). The recollected oral fluid was then analysed twice with a commercial ELISA for detection of PRRSV antibodies in oral fluid

Ability of ELISAs to detect antibodies against porcine respiratory and reproductive syndrome virus in serum of pigs after inactivated vaccination and subsequent challenge: Ability of ELISAs to detect antibodies against porcine respiratory andreproductive syndrome virus in serum of pigs after inactivated vaccination and subsequent challenge

Background: In this study, six enzyme-linked immunosorbent assays (ELISA), intended for routine porcine reproductive and respiratory syndrome virus (PRRSV) herd monitoring, are tested for their ability to detect PRRSV specific antibodies in the serum of pigs after vaccination with an inactivated PRRSV type 1 vaccine and subsequent infection with a highly pathogenic (HP) PRRSV field strain. For this reason, ten piglets (group V) from a PRRSV negative herd were vaccinated twice at the age of 2 and 4 weeks with an inactivated PRRSV vaccine. Ten additional piglets (group N) from the sameherd remained unvaccinated. Three weeks after second vaccination, each of the piglets received an intradermal application of an HP PRRSV field strain. Serum samples were taken before first vaccination as well as before and 3, 7, 10 and 14 days after HP PRRSV application. All serum samples were tested for PRRSV RNA by reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) as well as for PRRSV antibodies with all six study ELISAs. Results: At the beginning of the study (before vaccination), all of the piglets were PRRSV antibody negative with all study ELISAs. They also tested negative for PRRSV RNA measured by RT-qPCR. From day 3 after HP PRRSV application until the end of the study, a viremia was detected by RT-qPCR in all of the piglets. On day 0 (day of HP PRRSV application), nine out of ten piglets of the pre-vaccinated group tested PRRSV antibody positive with one of the tested ELISAs, although with lower S/P values than after infection. On day 10 after HP PRRSV application, all study ELISAs except one had significantly higher S/P or OD values, respectively more positive samples, in group V than in group N. Conclusions: Only one of the tested ELISAs was able to detect reliably PRRSV antibodies in pigs vaccinated with an inactivated PRRSV vaccine. With most of the tested ELISAs, higher S/P values respectively more positive samples after PRRSV infection were seen in the pre-vaccinated group than in the non-vaccinated

Ability of ELISAs to detect antibodies against porcine respiratory and reproductive syndrome virus in serum of pigs after inactivated vaccination and subsequent challenge: Ability of ELISAs to detect antibodies against porcine respiratory andreproductive syndrome virus in serum of pigs after inactivated vaccination and subsequent challenge

Background: In this study, six enzyme-linked immunosorbent assays (ELISA), intended for routine porcine reproductive and respiratory syndrome virus (PRRSV) herd monitoring, are tested for their ability to detect PRRSV specific antibodies in the serum of pigs after vaccination with an inactivated PRRSV type 1 vaccine and subsequent infection with a highly pathogenic (HP) PRRSV field strain. For this reason, ten piglets (group V) from a PRRSV negative herd were vaccinated twice at the age of 2 and 4 weeks with an inactivated PRRSV vaccine. Ten additional piglets (group N) from the sameherd remained unvaccinated. Three weeks after second vaccination, each of the piglets received an intradermal application of an HP PRRSV field strain. Serum samples were taken before first vaccination as well as before and 3, 7, 10 and 14 days after HP PRRSV application. All serum samples were tested for PRRSV RNA by reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) as well as for PRRSV antibodies with all six study ELISAs. Results: At the beginning of the study (before vaccination), all of the piglets were PRRSV antibody negative with all study ELISAs. They also tested negative for PRRSV RNA measured by RT-qPCR. From day 3 after HP PRRSV application until the end of the study, a viremia was detected by RT-qPCR in all of the piglets. On day 0 (day of HP PRRSV application), nine out of ten piglets of the pre-vaccinated group tested PRRSV antibody positive with one of the tested ELISAs, although with lower S/P values than after infection. On day 10 after HP PRRSV application, all study ELISAs except one had significantly higher S/P or OD values, respectively more positive samples, in group V than in group N. Conclusions: Only one of the tested ELISAs was able to detect reliably PRRSV antibodies in pigs vaccinated with an inactivated PRRSV vaccine. With most of the tested ELISAs, higher S/P values respectively more positive samples after PRRSV infection were seen in the pre-vaccinated group than in the non-vaccinated

Subclinical Infection with Avian Influenza A H5N1 Virus in Cats

Avian influenza A virus subtype H5N1 was transmitted to domestic cats by close contact with infected birds. Virus-specific nucleic acids were detected in pharyngeal swabs from 3 of 40 randomly sampled cats from a group of 194 animals (day 8 after contact with an infected swan). All cats were transferred to a quarantine station and monitored for clinical signs, virus shedding, and antibody production until day 50. Despite unfamiliar handling, social distress and the presence of other viral and nonviral pathogens that caused illness and poor health and compromised the immune systems, none of the cats developed clinical signs of influenza. There was no evidence of horizontal transmission to other cats because only 2 cats developed antibodies against H5N1 virus

Efficacy of live attenuated porcine reproductive and respiratory syndrome virus 2 strains to protect pigs from challenge with a heterologous Vietnamese PRRSV 2 field strain

Abstract Background Effective vaccines against porcine reproductive and respiratory syndrome virus (PRRSV), especially against highly pathogenic (HP) PRRSV are still missing. The objective of this study was to evaluate the protective efficacy of an experimental live attenuated PRRSV 2 vaccine, composed of two strains, against heterologous challenge with a Vietnamese HP PRRSV 2 field strain. For this reason, 20 PRRSV negative piglets were divided into two groups. The pigs of group 1 were vaccinated with the experimental vaccine, group 2 remained unvaccinated. All study piglets received an intranasal challenge of the HP PRRSV 2 on day 0 of the study (42 days after vaccination). Blood samples were taken on days 7 and 21 after vaccination and on several days after challenge. On day 28 after challenge, all piglets were euthanized and pathologically examined. Results On days 7 and 21 after vaccination, a PRRSV 2 viraemia was seen in all piglets of group 1 which remained detectable in seven piglets up to 42 days after vaccination. On day 3 after challenge, all piglets from both groups were positive in PRRSV 2 RT-qPCR. From day 7 onwards, viral load and number of PRRSV 2 positive pigs were lower in group 1 than in group 2. All pigs of group 1 seroconverted after PRRSV 2 vaccination. PRRSV antibodies were detected in serum of all study pigs from both groups from day 14 after challenge onwards. In group 2, moderate respiratory symptoms with occasional coughing were seen following the challenge with HP PRRSV 2. Pigs of group 1 remained clinically unaffected. Interstitial pneumonia was found in four piglets of group 1 and in all ten piglets of group 2. Histopathological findings were more severe in group 2. Conclusions It was thus concluded that the used PRRSV 2 live experimental vaccine provided protection from clinical disease and marked reduction of histopathological findings and viral load in pigs challenged with a Vietnamese HP PRRSV 2 field strain