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Fowl adenovirus infections have a significant economic impact, especially in the production of broilers. It is considered the leading cause of three syndromes: adenoviral gizzard erosions and ulcerations, inclusion body hepatitis, and hepatitis-hydropericardium syndrome. A critical feature of this virus is its immunosuppressive effect, via suppressing humoral and cellular immunity.

West Nile fever is a vector borne viral disease that can affect humans, horses, birds and sometimes other species of animals. Every year West Nile fever is detected in the human population in Serbia. The disease often occurs in a subclinical form, but most clinically evident cases occur in horses. Therefore, horses are recommended as a sentinel species for monitoring the general incidence of West Nile fever in a specific territory. Our goal was to determine the prevalence of antibodies against West Nile fever virus in horses in the Belgrade epizootiological area. We examined serum samples from 77 horses to determine the seroprevalence of West Nile fever virus in horses throughout the city of Belgrade. Sera were tested by commercial ELISA tests for detection of specific IgG-class antibodies to West Nile fever virus and for the detection of specific IgM-class antibodies to confirm the presence of old and acute (recent) infections in horses. The results confirmed that West Nile fever virus is widespread, detected in 70.1% of the surveyed horse population in Belgrade, and we also detected 5.1% of acute cases had occurred due to horses being infected in 2019. The seroprevalence of West Nile virus in the horse population in the municipality of Belgrade is increasing.

The presence of bovine parainfluenza virus type 3 (BPIV3) was examined in 119 nasal swabs collected from cattle with severe respiratory infection. All samples were conducted for virus isolation on the MDBK cell line. The cytopathic effect was observed after 48h to 72h in cells inoculated with eight samples (8/119; 6.7%). The confirmation of isolated strains of BPIV3 was done by the virus-neutralization test. In addition, all samples of bovine nasal swabs were also examined for the presence of BPIV3 virus using RT-PCR with primers specific for the part of HN gene. The presence of BPIV3 was detected in eight samples (8/119; 6.7%) that were also positive upon virus isolation. The molecular characterization based on nucleotide sequencing of the part of the HN gene showed that all BPIV3 isolates belonged to genotype C of BPIV3. They branched in one distinct cluster with three different branches, but these branches were very similar to each other (98.1% to 99.8%). Serbian BPIV3c isolates were most similar to the Chinese BPIV3c isolates SD0805, SD0809 and SD0835 (from 97.92% to 99.7%), and to South Korean (12Q061), Japanese (HS9) and American (TVMDL16 and TVMDL20) BPIV3c strains (from 97.1% to 98.8%), and distinct from American (TVMDL15and TVMDL17) and Australian (Q5592) BPI3V genotype B strains (only 79.9% to 82.3% similarity), as well as from the genotype A BPIV3 strains from different countries published in GenBank.

Rabies is a disease that occurs both in animals and people, with relatively long period of incubation, intense clinical course and fatal ending. Majority of cases of illnes and death in people are caused by the standard rabies virus. According to books of regulations on suppression and eradiction of rabies from 1988. and 2009., each suspected rabies has to be laboratory confirmed. From 2006. to 2012. within the passive surveilance, 3549 samples of brain tissue were examined for the presence of rabies virus. The virus was confirmed in 923 samples by using the method of direct imunofluorescence. From 2006. to 2012. there were diagnosed 192, 160, 233, 181, 104, 43 and 10 positive cases, respectively. For the purpose of rabies eradiction at the territory of the Republic of Serbia, a regional project of oral vaccination of foxes against rabies has been implemented since 2010.Within monitoring of the effectiveness of oral vaccination against rabies which was carried out at the end of 2011. and at the beginning of 2012., there were examined 1385 samples, out of which 11 reacted positively. The virus was dominantly present in the fox population. During 2008. and 2009., a relatively large number of rabid cats was registered, what indicates a transmission of rabies from the fox to the cat population. The incidence of rabies at the territory of Serbia significantly differs from one epizootic area to another. Northern parts of the country (Sombor and Subotica epizootic regions) have more favorable situation with only two cases of rabies for the last 7 years. In the period until 2010., in Pozarevac, Novi Sad, Jagodina, Pancevo, Belgrade and Nis epizootic region, a gradual decline in number of positive cases was noticed. International project for oral vaccination of foxes against rabies which has been implemented at the territory of the Republic of Serbia and neighboring countries, influenced a significant reduction of registered rabies cases. [Projekat Ministarstva nauke Republike Srbije, br. TR31084 i TR31088]

Classical swine fever (CSF) is a highly contagious disease of pigs leading to significant economic losses worldwide. Classical swine fever virus can be classified into three genogroups, each consisting of three or four subgroups. However, there is a lack of knowledge on the genotypes of CSFV isolates in Republic of Serbia. This study, based on the sequences analysis of partial E2 gene and 5' non coding region (NCR) of 15 CSFV isolated during 2006-2008 from domestic pigs, revealed that all were clustered into genetic group 2.3. Additionally, we showed that the two most often used real time RT-PCR assays were able to detect all local CSF viruses circulated in Serbia in the last years during intensive vaccination campaign against CSF. [Projekat Ministarstva nauke Republike Srbije, br. TR 31075 and TR 31088]

Swine influenza presents a very important health and economic issue in pig productions worldwide. Viruses that cause the disease are genetically very diverse but usually belong to the H1N1, H1N2 and H3N2 subtype of influenza A viruses. In this study, we sequenced and analyzed the full genome of viruses detected in swine from seven commercial farms. Through the analysis of the complete sequences of internal gene cassette together with previously characterized HA and NA genes we found three different genotypes amongst five completely sequenced viruses. Two viruses possessed a completely H1avN1 genotype (40%) and belonged to the H1avN1 lineage, which is prevalent in European swine populations. The other three viruses have arisen through the reassortment of the genes of H1avN1 and H1N1pdm09 lineages. In one sample we detected coinfection with viruses of H3N2 subtype with genes of H1avN1, H1N1pdm09 and A/swine/Gent/1/1984-like H3N2 lineages that presents a potential environment for the generation of a triple reassortant virus. The presence of the H1N1pdm09 origin M gene in this sample implies the potential risk of the introduction of these viruses into the human population. Phylogenetic analysis of internal gene cassette revealed slower evolution within genes of H1N1pdm09 lineage than those of H1avN1 lineage.

Hepatitis E virus (HEV), the zoonotic agent of infectious hepatitis, is present in swine farms in different geographical areas. Little is known about the mechanism of liver damage and type of local immune response by HEV in swine. Therefore, the aim of this study was to determine the morphological and immunophenotypic characteristics of hepatic lesions caused by hepatitis E virus in naturally infected swine. In this study, liver samples of 12 slaughtered 10 weeks old pigs which were RT-PCR positive for HEV RNA in rectal swab samples have been used. Livers were macroscopically examined and samples were taken for histopathological, immunohistochemical (CD3, CD79α and TGF-β1), semiquantitative, morphometric analysis, RT-nested-PCR, PCR and bacteriological analysis. Microscopically, mild and moderate multifocal lymphoplasmacytic hepatitis was observed. Apoptotic bodies were observed as areas of focal eosinophilic condensation in the cytoplasm of 33.33% liver samples, while in 16.67% liver samples portal fibrosis was detected. Immunohistochemically, portal and lobular lymphocytes in the mononuclear liver infiltrate were predominantly CD3+ T cells (234.80 ± 79.98). An intense TGF-β1 positive reaction was observed within the mononuclear cell infiltrate as well as polymorphonuclear cells in liver samples with apoptosis of hepatocytes. In all 12 tested liver samples HEV RNA was detected by RT-nested-PCR. HEV is noncytopathic, and this finding provides further evidence for an immune mediated pathogenesis in hepatitis E virus infection in swine. Also, the role of CD3+ cells in hepatocyte damage is clearly demonstrated.

Porcine Kobuvirus (PKV) infection is very common in pigs throughout the world. Since it has never been investigated in Serbia, to contribute to the knowledge of Porcine Kobuvirus, its role, and distribution, we tested 200 samples from domestic pigs and wild boars. From domestic pigs, 10 fecal, 22 spleen and 68 serum samples, and 100 spleen samples from wild boars were tested. The virus prevalence determined by real-time RT-PCR in domestic pigs was 22% and in wild boars 6%. The phylogenetic analysis of 3D region revealed that Serbian strains are closest related to the Hungarian strain from wild boar from 2011. This is the first report on PKV in Serbia in domestic pigs and wild boars, implying its wide circulation. Although the infection could not be directly related to any clinical manifestation, the frequency of virus found in feces suggests viral affinity to the gastrointestinal tract. However, due to the rather ubiquitous presence of PKV, the clinical and pathological assessment have to be considered when PKV infection is diagnosed., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Considering the intensive trading nowadays, the honey from the local market was tested for the presence of the six most common bee viruses. To prove the suitability of honey as a sample for the bee viruses detection, the set of different sample types taken directly from the hives we comparatively tested. The study included 30 samples of domestic and 5 samples of imported honey. Additionally, we tested 40 sets of samples including live bees, dead bees, and the honey taken from four apiaries for the evaluation of honey suitability for the virus detection, Two out of the six most common bee viruses were detected in the samples of honey from the market. Black queen cell virus (BQCV) genome was found in 24 domestic honey samples and Kashmir bee virus (KBV) genome was detected in one sample of imported honey. The nucleotide sequences of 24 BQCV isolates showed the highest identity (86.4%) with strains from Europe at the polyprotein gene, whilst the Serbian isolates between each other showed 98.5% similarity. By comparative testing of the different type of samples, in three out of four apiaries BQCV genome was detected in both bees and honey. Evaluating the suitability of honey for the detection of the viral disease by simultaneous testing of live, dead bees, and honey from the same hive, it was shown that the honey can be successfully used for the detection of BQCV. Since, as of yet, there has been no evidence of KBV circulation in Serbia, after its detection in imported honey, there is a substantial risk of its introduction and consequently the need for its surveillance. Therefore, the programs of bee diseases screening should be included in the regular control procedures for the international trade. In addition to this benefit, honey gives an opportunity to beekeepers for continuous monitoring of bees' health status.

Bovine viral diarrhea (BVD) is one of the most economically important diseases of cattle. With its very high prevalence, cattle kept on pastures become a source of the virus for the wildlife which, due to their susceptibility, then easily can serve as a source for re-infections of cattle. Therefore, we investigated the BVDV infection in Serbian wild boar and assessed the role of wild boar in BVDV epidemiology including possible spreading to domestic species. This study was based on examination of 50 spleen samples which were collected from wild boars located in Eastern Serbia during the hunting season 2016/2017. BVDV genome was detected in 4 of 50 samples (8%). Phylogenetic analysis based on 5'UTR revealed that BVDV strains from wild boars shared 100% identity. Belonging to the BVDV 1f subgenotype, the most common in cattle, we showed that BVDV infections of wild boar occurred as a result of either direct or indirect contact with domestic animals. Therefore, the occurrence of infectious disease in wildlife emphasizes the need to study the pathogens shared by wildlife and domestic animals by investigating the incidence of pathogens and disease patterns of those populations., (Copyright © 2018 Elsevier Ltd. All rights reserved.)