Serological and molecular investigation of the prevalence of Aujeszky's disease in feral swine (Sus scrofa) in the subregions of the Pantanal wetland, Brazil

Suid alphaherpesvirus 1 of wild boar origin as a recent source of Aujeszky's disease in carnivores in Germany

BACKGROUND

The high susceptibility of carnivores to Suid Alphaherpesvirus 1 [SuAHV1, synonymous pseudorabies virus (PrV)], renders them inadvertent sentinels for the possible occurrence of Aujeszky's disease (AD) in domestic and wild swine populations. The aim of this study was to epidemiologically analyse the occurrence of PrV infections in domestic and wild animals in Germany during the last three decades and to genetically characterise the causative PrV isolates.

METHODS

PrV in dogs was detected using standard virological techniques including conventional and real time PCR, virus isolation or by immunohistochemistry. Available PrV isolates were characterized by partial sequencing of the open gC reading frame and the genetic traits were compared with those of archived PrV isolates from carnivores and domestic pigs from Germany before the elimination of AD in the domestic pig population.

RESULTS

During 1995 and 2022, a total of 38 cases of AD in carnivores, e.g. dogs and red foxes, were laboratory confirmed. Sequencing and subsequent phylogenetic analysis of PrV isolates established a strong connection between AD cases in carnivores and the occurrence of PrV infections in European wild boars in the end phase of and after elimination of AD from the domestic pig population. While PrV infections occur at low numbers but regularly in hunting dogs, interestingly, PrV was not observed in grey wolves in Germany. In none of 682 dead-found grey wolves and wolf-dog hybrids tested from Germany during 2006-2022 could PrV infection be detected by molecular means.

CONCLUSIONS

Although PrV has been eliminated from domestic pigs, spillover infections in domestic and wild carnivores should always be expected given the endemic presence of PrV in wild pig populations. Since detection of PrV DNA and virus in carnivores is sporadic even in areas with high seroprevalence of PrV in wild pigs, it may not reflect the full diversity of PrV.

Detection of pseudorabies virus antibody in swine serum and oral fluid specimens using a recombinant gE glycoprotein dual-matrix indirect ELISA

Pseudorabies (Aujeszky disease) virus (PRV) was eliminated from domestic swine in many countries using glycoprotein E (gE)-deleted vaccines and serum antibody gE ELISAs, but PRV continues to circulate in some regions and in most feral swine populations in the world. We created a dual-matrix (serum and oral fluid) indirect IgG gE ELISA (iELISA) and evaluated its performance using samples from 4 groups of 10 pigs each: negative control (NC), vaccination (MLV), PRV inoculation (PRV), and vaccination followed by challenge (MLV-PRV). All serum and oral fluid samples collected before PRV challenge and all NC samples throughout the study were negative for gE antibodies by commercial blocking ELISA (bELISA) and our iELISA. Nasal swab samples from 9 of 10 animals in the PRV group were gB quantitative PRC (qPCR) positive at 2 days post-inoculation (dpi). The oral fluid iELISA detected a significant S/P response in the PRV (p = 0.03) and MLV-PRV (p = 0.01) groups by 6 dpi. ROC analyses of serum bELISA (n = 428), serum iELISA (n = 426), and oral fluid iELISA (n = 247) showed no significant differences in performance (p > 0.05). Our data support the concept of PRV surveillance based on oral fluid samples tested by an indirect gE ELISA.

Serosurvey for Pseudorabies (Aujeszky's Disease) in Free-Range Wild Boars (Sus scrofa) of Brazil

Free-ranging wild boars (Sus scrofa) from two different Brazilian biomes were sampled. Only one of 36 (2.8%) animals tested from central-western Brazil were positive for antibodies against pseudorabies virus (PRV) by enzyme-linked immunosorbent assay. Peccaries and other wildlife species can be exposed to PRV in these areas. In addition, wild boars could have impact on livestock and PRV eradication.

Epizootic situation of Aujeszky's disease within the territory of the Republic of Kazakhstan

Background

The relevance of the study is determined by the danger that this disease poses to all types of domestic animals in the Republic of Kazakhstan, as well as the significant damage caused by this situation to the entire agriculture of the Republic of Kazakhstan. Timely and competent analysis of the epizootic situation for this disease in the country will reliably determine the development tendencies of this condition and predetermine a set of measures that should be taken to combat this animal disease in agricultural regions of the Republic of Kazakhstan.

Aim

This study examines the development of the epizootic situation of Aujeszky's disease within the territory of the Republic of Kazakhstan.

Methods

To achieve the set research goal, a combination of quantitative and qualitative research methods are used.

Results

The results of this research article can be of significant importance for livestock breeders in the Republic of Kazakhstan, who are working on raising the number of pigs and other types of domestic animals and are interested in a further increase in the number.

Conclusion

From a practical standpoint, the significance of this study is conditioned by the possibility of searching and determining the main directions of the spread of the disease under consideration in agricultural lands and regions of the Republic of Kazakhstan, as well as taking a set of measures to eradicate such a disease and prevent its future occurrence in the country.

Detection of pseudorabies virus antibody in swine oral fluid using a serum whole-virus indirect ELISA

We evaluated the detection of pseudorabies virus (PRV) antibodies in swine oral fluid. Oral fluid and serum samples were obtained from 40 pigs allocated to 4 treatment groups (10 pigs/group): negative control (NC); wild-type PRV inoculation (PRV 3CR Ossabaw; hereafter PRV); PRV vaccination (Ingelvac Aujeszky MLV; Boehringer Ingelheim; hereafter MLV); and PRV vaccination followed by PRV inoculation at 21 d post-vaccination (MLV-PRV). Using a serum PRV whole-virus indirect IgG ELISA (Idexx Laboratories) adapted to the oral fluid matrix, PRV antibody was detected in oral fluid samples from treatment groups PRV, MLV, and MLV-PRV in a pattern similar to serum. Vaccination alone produced a low oral fluid antibody response (groups MLV and MLV-PRV), but a strong anamnestic response was observed following challenge with wild-type virus (group PRV). Analyses of the oral fluid PRV indirect IgG ELISA results showed good binary diagnostic performance (area under ROC curve = 93%) and excellent assay repeatability (intra-class correlation coefficient = 99.3%). The demonstrable presence of PRV antibodies in swine oral fluids suggests the possible use of oral fluids in pseudorabies surveillance.

Evolutionary Diversity of Suid Herpesvirus 1 Based on Ul44 Partial Sequences

OBJECTIVE

The aim of this study was to use partial Ul44 sequences (glycoprotein C) of Suid herpesvirus 1 to examine the evolution and dynamics of the virus in different periods and hosts.

METHODS

Phylogenetic trees were constructed using the software MrBayes after analysis in the software jModelTest to evaluate the best phylogenetic models. The software SplitsTree 4.0 was used to create phylogenetic networks, and the BEAST program was used to generate data on phylogeography. Replication kinetics and serum neutralization tests were applied to tree strains from different phylogenetic groups.

RESULTS

Ul44 sequences derived from domestic swine and wild swine clustered in different clades and had different selective pressures depending on the host. We found no differences in replication kinetics and serum neutralization tests in the strains tested. Data show that the evolution of herpesviruses is complex, and different genetic groups may be evolving at different rates. Ul44 is an important marker for molecular evolution and epidemiology studies, but it is not useful for biological information.