Presence of Mycoplasma bovis in Bulk Tank Milk and Associated Risk Factor Analysis in Serbian Dairy Farms

Mycoplasma bovis (M. bovis) is a significant pathogen responsible for highly transmissible mastitis in cattle globally. It primarily spreads through colostrum, milk, and semen. Cows with persistent infections act as carriers, intermittently releasing the pathogen, making their milk a pivotal factor in infection transmission. Given the limited seroprevalence surveys in Serbia, this study aimed to detect M. bovis presence in bulk tank milk (BTM), determine route shedding, and evaluate infection risks. BTM samples were collected from 115 dairy farms across Serbia, with M. bovis DNA detected in 11 out of the 115 samples by real-time PCR. Additionally, M. bovis was detected in 1.30% of nasal swabs sampled from apparently healthy animals. A univariate analysis of the risk factors associated with M. bovis presence in the BTM samples revealed correlations with factors such as the breed, farm seropositivity, pre-milking and post-milking disinfection practices, farm type, cow population, milk yield, number of cows in the BTM samples, and parity. Seropositive farms exhibited the highest likelihood of M. bovis presence in milk. Moreover, pre- and post-milking disinfection practices and highly productive cows yielding over 8000 L of milk were identified as risk factors for PCR-positive BTM. In a multivariable mixed regression analysis, a risk factor for the presence of M. bovis infection in the BTM sample was the Holstein breed. These findings underscore a relatively high prevalence of M. bovis in BTM within Serbian dairy farms, suggesting a potential risk for M. bovis spreading through milk and oral route of calves' infection.

Cross-sectional serosurvey of selected infectious diseases in wild ruminants in Serbia

The role of wildlife in maintaining infectious diseases in veterinary medicine is often neglected, although the disease eradication process in domestic animals is continuously affected by the risk of pathogens transmission from wildlife as a primary source. The main aim of this paper was to estimate the prevalence and distribution of selected infectious diseases in wild ruminants in Serbia. In total, 259 sera from wild ruminants were tested for specific antibodies to bluetongue virus, Schmallenberg virus, Bovine viral diarrhea/border disease virus, Capripox virus, West Nile fever virus, Bovine herpes virus-1, Coxiella burnetii, Brucella spp., and Leptospira spp. Specific Capripox virus and Leptospira spp. antibodies were not detected in any of the 259 wild ruminant samples. Although one animal was detected positive for BVDV/BDV specific antibodies, with 99.8% confidence, the prevalence of BVD within this population could be very low i.e. essentially free from BVD infection. One and three positive animals were detected for Brucella spp. and Coxiella burnetii antibodies, respectively. Bovine herpes virus-1 specific antibodies were detected in 20.85% of the samples. The estimated seroprevalence of vector-borne diseases was 20.5% for Schmallenberg disease, 34.3% for West Nile fever, and 38.6% for Bluetongue. Considering the reported results, wildlife health status is a result of different factors in complex relation, such as the presence of disease in domestic animals, disease nature, pathogen characteristics, environmental factors, presence, and vector competence. Wildlife should be considered not only as a risk but as a source of important information on disease distribution and its indicators.

Protoparvovirus carnivoran 1 infection of golden jackals Canis aureus in Serbia

Parvoviruses are among the major animal pathogens that can cause considerable health disorders ranging from subclinical to lethal in domestic and wild animals. Golden jackal (Canis aureus), an expanding European species, is a reservoir of many pathogens, including vector-borne diseases and zoonoses. Given the importance of parvovirus infections in dogs and cats, this study aimed to unfold the virus prevalence and molecular characterisation in the golden jackal population in Serbia. The spleen samples from 68 hunted jackals during 2022/2023 were tested for the VP2-specific genome region of Protoparvovirus carnivoran 1 by PCR. BLAST analysis of partial VP2 sequences obtained from three animals (4.4%) revealed the highest similarity to Protoparvovirus carnivoran 1, genogroup Feline panleukopenia virus, which is the second report on FPV infection in jackals. Based on specific amino acid residues within partial VP2, the jackals' Protoparvovirus carnivoran 1 was also classified as FPV. One jackal's strain showed two synonymous mutations at positions 699 and 1167. Although species cross-transmission could not be established, jackals' health should be maintained by preventing the transmission of viruses to native species and vice versa. Although jackals are considered pests, their role as natural cleaners is of greater importance. Therefore, further monitoring of their health is needed to understand the influence of infectious diseases on population dynamics and to determine the relationship between domestic predators and jackals and the direction of cross-species transmission.

Genetic analysis reveals multiple intergenic region and central variable region in the African swine fever virus variants circulating in Serbia

This study provides the first comprehensive report on the molecular characteristics of African swine fever virus (ASFV) variants in Serbia between 2019 and 2022. Since its first observation in July 2019, the disease has been found in wild boar and domestic swine. The study involved the analysis of 95 ASFV-positive samples collected from 12 infected administrative districts in Serbia. Partial four genomic regions were genetically characterized, including B646L, E183L, B602L, and the intergenic region (IGR) between the I73R-I329L genes. The results of the study suggest that multiple ASFV strains belonging to genotype II are circulating in Serbia, as evidenced by the analysis of the IGR between I73R-I329L genes that showed the most differences. Furthermore, the phylogenetic analysis of the B602L gene showed three different clades within the CVR I group of ASFV strains. Regarding the IGR, 98.4% were grouped into IGR II, with only one positive sample grouped into the IGR III group. These findings provide essential insights into the molecular characteristics of ASFV variants in Serbia and contribute to the knowledge of circulating strains of ASFV in Europe. However, further research is necessary to gain a better understanding of ASFV spread and evolution.

Retrospective phylogenetic analysis of rabies virus G and N genes from Serbia

Rabies is a viral disease of the central nervous system of all warm-blooded animals and one of the oldest and most important zoonoses. In the Republic of Serbia, rabies is controlled by compulsory vaccination of dogs and cats and oral vaccination of wild carnivores, which has been implemented since 2010. In the period 2009-2018, 367 rabies cases were recorded. The last rabies case in Serbia was recorded in 2018 in a red fox (Vulpes vulpes), while the last case in dogs was diagnosed in 2011. This study aimed to perform a retrospective phylogenetic analysis of G and N genes of the rabies virus from Serbia from 2009 to 2018 to understand sources and pathways of infection better and to enable molecular virus tracing in the future based on the association of rabies virus genetic lineages with the geographic distribution. For the phylogenetic analysis of the rabies virus, 14 historically positive brain samples of red foxes from 2009 to 2018, collected in central Serbia, were used. All field strains from Serbia were identified as classic rabies virus and grouped within the Cosmopolitan lineage. Phylogenetic analysis of N gene sequences revealed that 13 rabies virus strains (92.9%) from Serbia belonged to the EE sub-lineage of isolates, while one virus (7.1%) ON988027 from 2011 clustered together with isolates from the WE sub-lineage.

Seroprevalence of Viral Enzootic Diseases in Swine Backyard Farms in Serbia

Contrary to pig farming in developed Western countries, in a large part of the world, pigs are still traditionally kept in small backyard farms, usually for family needs. Their main characteristics are low biosecurity, swill feeding, natural breeding and uncontrolled trade. Given the high number of backyard farms in Serbia and the risk they are thought to pose to intensive pig farming, the main aim of this study was to evaluate the prevalence of major viral diseases of swine among traditionally kept pigs in small holdings with low biosecurity. For this investigation, 222 serum samples from 69 backyard holdings were randomly selected and tested for antibodies to Porcine Reproductive and Respiratory Syndrome virus (PRRSV), Aujeszky's disease virus (ADV), Porcine Parvovirus (PPV) and Swine influenza Virus (SIV) by enzyme-linked immunosorbent assay (ELISA). The herd-level seroprevalence of PRRS, Aujeszky's disease and PPV was 2.9%, 27.5% and 37.7%, respectively. Swine influenza seroconversion was not confirmed in any of the tested holdings. Despite widely distributed PPV and AD in backyard farms in Serbia, almost 50% of them are still negative for all the tested diseases. The backyard farms must be monitored, and owners must be educated as their role in eradication programs and obtaining country-free status may be crucial.

Genetic analysis of influenza A viruses of swine from commercial farms in Serbia

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.

Prevalence and genotype distribution of caprine papillomavirus in peripheral blood of healthy goats in farms from three European countries

Caprine papillomaviruses (ChPVs, Capra hircus papillomaviruses) were detected and quantified for the first time using droplet digital polymerase chain reaction (ddPCR) in blood samples of 374 clinically healthy goats from farms located in Italy, Romania, and Serbia. Overall, ddPCR revealed ChPV DNA in 78 of the 374 examined samples, indicating that ~21% of the goats harbored circulating papillomavirus DNA. In particular, in Italian goat farms, ChPV genotypes were detected and quantified in 58 of 157 blood samples (~37%), 11 of 117 samples from Serbian farms (~9.4%), and 9 of 100 from Romanian blood samples (9%). Blood samples from Italian goat farms showed a high prevalence of ChPV1, which was detected in 45 samples (28.6%). The ChPV2 genotype was detected in 13 samples (~8.3%). Therefore, significant differences in prevalence and genotype distributions were observed. On Serbian and Romanian farms, no significant differences were observed in the genotype prevalence of ChPVs. Molecular findings are consistent with ChPV prevalence, characterized by a territorial distribution similar to that of papillomaviruses in other mammalian species. Furthermore, this study showed that ddPCR is a very sensitive and accurate assay for ChPV detection and quantification. The ddPCR may be the molecular diagnostic tool of choice, ultimately providing useful insights into the molecular epidemiology and field surveillance of ChPV.

Molecular characterization of Canine parvovirus type 2 from diarrheic dogs in Serbia from 2008 to 2020

Canine parvovirus 2 (CPV-2) is the causal agent of canine parvovirosis an infectious disease with the high fatality rate among dogs. However, in Serbia, it has never been investigated thoroughly. This study was conducted on samples collected from dogs with diarrhea in anamnesis, submitted for various reasons to the Institute of Veterinary Medicine of Serbia, and stored in the sample bank. In total, 50 rectal swab samples were collected from the period 2008 to 2020, and consequently tested. Out of 50 rectal swab samples, the CPV-2 genome was detected in 14 (28%). This retrospective study showed the presence of three different subtypes of CPV-2 in diarrheic dogs during the last 12 years in Serbia. CPV-2a was the most prevalent subtype (60%) followed by CPV-2b (30%), and CPV-2c (10%). Interestingly, CPV-2a had been the predominantly detected subtype up until 2018. Nevertheless in 2019, there was the first detected occurrence of the CPV-2b, followed by the first detection of the CPV-2c in 2020. This study reports the evidence and distribution of CPV-2 from 2008 to 2020, providing new information about the presence of virus strains in Serbia.

SEROPREVALENCE OF PORCINE RESPIRATORY CORONAVIRUS AND TRANSMISSIBLE GASTROENTERITIS VIRUS INFECTIONS ON COMMERCIAL PIG FARMS IN SERBIA

Porcine respiratory coronavirus is an enzootic, viral, respiratory disease of pigs, which manifests with mild clinical signs, but it takes part in the etiopathogenesis of the porcine respiratory disease complex. The virus was first discovered in Belgium in 1984 as a deletion mutant of the transmissible gastroenteritis virus. The two viruses are strongly antigenically related which is why they cross-react in serological tests. In this study, we tested 276 serum samples from different categories of pigs using ELISA test, which allows differentiation between the porcine respiratory coronavirus infection and transmissible gastroenteritis. The seroconversion for coronavirus infection was determined in 80.4% of tested samples. Out of 222 positive samples, 219 samples (98.6%) were positive for porcine respiratory coronavirus antibodies, while 3 (1.01%) samples were positive for transmissible gastroenteritis virus antibodies. Depending on the production category, 97.7% of piglets, 83% of sows, and 35% of gilts tested positive for porcine respiratory coronavirus antibodies. In total, 2.3% of piglets tested positive for transmissible gastroenteritis virus antibodies. Taking into account the characteristics of the ELISA test, its sensitivity and specificity, this result can be considered a false positive, because of a cross-reaction between the porcine respiratory coronavirus antibodies and the transmissible gastroenteritis virus. Specific antibodies in other swine production categories against the transmissible gastroenteritis virus were not determined.

Morphological and immunophenotypic characteristics of the liver of swine naturally infected with hepatitis E virus

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.

CARP EDEMA VIRUS DISEASE IN SERBIA - DISEASE OUT OF CONTROL

A poxvirus named carp edema virus (CEV), is the causative agent of carp edema virus disease (CEVD), which is an emerging disease of global concern that may cause high rates of morbidity and mortality in ornamental koi and common carp and. Common carp (Cyprinus carpio) is the most important fish species for warm‐water aquaculture in Serbia. CEVD was first time detected in Serbia in 2017. During 2017-2020 period, increasing number of CEVD outbreaks in carp farms is reported.  Carp were collected from farms in different regions of Serbia from 2017 to 2020. The fish were sampled for disease diagnosis because they exhibited lethargy and anorexia, which eventually led to mortality. Mortality started with clinical signs of hypoxia while fish swam slowly without escaping reactions. The gills were pale and covered with a thick mucus layer. In advanced cases, the lesions in the gills turned into a necrotizing form. A moderate to high amount of opportunistic freshwater bacteria were isolated from gills of diseased fish. By performing real-time PCR, CEV was detected in 38 samples of diseased carps from 21 carp farms. These outbreaks further confirm the spread of CEVD and the need for practitioners to be vigilant for outbreaks of this disease. To prevent further spreading of the disease, it is very important to introduce CEV testing before fish movement. To avoid further transmission of the virus to common carp populations in Serbia, testing of CEV should become part of fish disease surveillance programs. Fish health service should be aware of the presence of CEV in Serbia which may result in high losses in carp aquaculture. Action should be taken also to prevent transmission of CEV to carp populations in open waters.

Investigation of possible aetiological/triggering factors in porcine ear necrosis syndrome at a farrow-to-feeder pig system

At a commercial farrow-to-feeder pig system with 2,100 sows in Serbia, lesions resembling porcine ear necrosis syndrome were observed in 80% of the weaned pigs at 45-50 days of age. Pathomorphological examinations were carried out on 10 pigs that had been found dead. The gross lesions ranged from mild, superficial dermatitis to severe, deep inflammation with exudation, ulceration and necrosis. Histopathological examination revealed erosive and ulcerative dermatitis of the pinna with neutrophilic and lymphocytic infiltration and bacterial colonies in the crusts. Staphylococcus aureus (MRSA strain), Staphylococcus hyicus and Streptococcus group C were cultivated from eight, S. hyicus from two ear tissue scraping samples. All 10 samples were positive for treponemes and phylogenetic analysis of two polymerase chain reaction products confirmed the relationship to Treponema (T.) medium/vincentii and Treponema pedis. Treponemes were also detected in seven oral swabs that were analysed to obtain evidence of the transmission of this bacterium by ear biting. The contribution of non-infectious factors to this misbehaviour could not be ruled out as the crude protein concentration of the feed was inappropriate and the climate of the pig house was suboptimal. The concentrations of selected mycotoxins in the feed were not elevated. However, the contribution of both infectious and non-infectious factors to the onset of disease was most probable.

Comparison of performances between three commercial ELISA kits for detection of antibodies against Porcine Reproductive and Respiratory Syndrome Virus (PPRSV) in swine sera samples

Porcine Reproductive and Respiratory Syndrome (PRRS) is one of the most economically important diseases in pigs, worldwide. Just in the US, the total costs to the swine industry have been estimated at $664 million per year. Therefore, the continuous and reliable monitoring of the PRRS status of a pig herd is required in order to prevent and reduce costs due to this infection. Mostly used methods for diagnosis of PRRS infection nowadays are serological (ELISA) and molecular (PCR) ones. This study aimed to assess the sensitivity and specificity of three different commercially available ELISA kits for detection of antibodies against PRRSV (IDEXX PRRS X3 Ab Test (IDEXX, USA), INgezim PRRS Universal (Ingenasa, Spain), Pigtype PRRSV Ab (Qiagen, Germany)) using 91 blood serum samples collected from pigs in Serbia. Our study showed no significant differences in specificity and sensitivity between three commercially available ELISA kits. However, IDEXX ELISA proved to be more reliable kit for detecting antibodies against PRRSV with sensitivity of 97,4% and specificity of 98,1%, considering INgezim and Qiagen kits specificity of 92,5% and 83%, respectively, and sensitivity of 94,7 % for both kits. In order to achieve maximal reliability of obtained results, ELISA diagnostic protocol for diagnosis of PRRS infection should be complemented with additional tests such as PCR and virus neutralization test.

Molecular detection and characterization of Porcine Kobuvirus in domestic pigs and wild boars in Serbia

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.

Seroprevalence of hepatitis E in pigs and wild boars in the region of the city Belgrade

INTRODUCTION

Hepatitis E is considered an emerging human viral disease with many evidences of zoonotic nature of disease, and swine are the main reservoir of HEV. The aim of this study was to determine HEV seroprevalence in commercial pig farms, backyard pigs, slaughtered pigs and wild boars in the region of the city Belgrade.

METHODOLOGY

A total of 405 sera samples: 150 samples from 3 commercial pig farms, 70 samples from backyard pigs, 119 samples from slaughtered pigs and 66 samples from wild boars of the region of the city Belgrade, Serbia were analysed by commercial ELISA test.

RESULTS

The overall HEV seroprevalence in 3 commercial pig farms was 55.33% (83/150). All tested farms (farm A, B and C) were positive on the presence of anti-HEV antibodies, respectively 58% (29/50), 54% (27/50) and 54% (27/50). From 70 tested backyard pigs, 75.71% (53/70) were tested seropositive. In total, 26 backyard pig holidngs were confirmed as positive to anti-HEV antibodies (81.25%). At slaughterhouse, 25% (8/32) weaned piglets and 20.69% (18/87) fattening pigs were tested positive on anti-HEV antibodies. Overall HEV seroprevalence in tested wild boar population was 52.25% (36/66).

CONCLUSIONS

Detected very high seroprevalence of anti-HEV antibodies indicated an active circulation of HEV, being enzootic in the swine population, and wild boars, as well, in the region of the city Belgrade.

SEASONAL DYNAMICS OF THE PRESENCE OF CULICOIDES SPP. IN SERBIA IN THE PERIOD 2015-2016

Genus Culicoides spp. includes small insects 0.5-2 mm in length, usually grey or black and at first glance very similar to mosquitoes. They are strictly hematophagous, feeding by attacking hosts outdoors and indoors (although they are less susceptible to the stationing like Aedes mosquitoesdo). The sting is very painful at the injection site and often followed by hypersensibilisation with the consequent formation of allergic dermatitis. Inaddition, the insects carry and transmit a multitude of diseases, often of a zoonotic character, and therefore are of great epidemiological importance. In our country, continuous monitoring of Culicolides spp. has been carried out and seasonal dynamics of their appearance in the period 2015-2016 is presented in this article. During October 2015, the presence of Culicolides spp. was confirmed in 10.00% of samples; in November, their presence was not established, whereas in December, 2.35% of samples proved positive for the presence of Culicolides spp. During 2016, from January to March, no Culicolides spp. were found in any of the examined samples. During April, their prevalence was 9.63%, in May - 6.74%, in June - 3.70%, in July - 15.78%, in August - 18.07%, in September - 27.27%, and in October - 45.65%. In Serbia, the dominant Culicoides spp. species are Obsoletus complex and Pulicaris complex established in 57.21% and 33.37% of samples, respectively. Other species are present in lesser extent. In Obsoletus complex, the dominant species was Culicoides obsoletus/scoticus. The percentage of Culicoides obsoletus /scoticus males in samples was 25.52%. Non-pigmented (young) females were present in 66.06% of samples; females who took blood in 7.55% and 0.87% were gravid females. In Pulicaris complex, the dominant species was Culicoides pulicaris. Males of Culicoides pulicaris were found in 19.23% of samples, non-pigmented (young) females in 70.96%, females who took blood in 9.08% while 0.73% were gravid females.

STURGEON DISEASES IN AQUACULTURE

Sturgeon aquaculture is economically important in many countries, for both meat and caviar production. Sturgeon is the common name for 27 species of fish belonging to the family Acipenseridae. Among them, only the sterlet (Acipenser ruthenus) and the Siberian sturgeon (Acipenser baerii) completes the lifecycle in fresh water. In Serbia, in the last few years, aquaculture enterprises have shown more interest in farming these fish species. Also, the importance of sturgeon aquaculture grows due to the rapid decrease of wild populations caused by overfishing, water pollution and destruction of habitat. The development of sturgeon aquaculture activities has been accompanied by the disease outbreaks, and possibility of the emergence and rapid dissemination of several infectious disease agents may represent serious problem in sturgeon aquaculture. Several viral, bacterial, fungal and parasitic diseases have been reported worldwide. Due to the limited knowledge about epizootiology and disease control methods, infectious diseases may represent a major challenge in sturgeon aquaculture. Moreover, none of the diseases reported in sturgeon are regulated in the World Organization for Animal Health (OIE) or European Union (EU) legislations. Due to the increasing interest in sturgeon aquaculture in Serbia present study is focused on the most important pathogens that may represent a threat to sturgeon aquaculture in Serbia.

CYPRINID HERPESVIRUS DISEASES

Cyprinidae, the largest known fish family including carp and minnows, has worldwide distribution with many species that are economically important in aquaculture. As would be expected, many viral pathogens can affect this group. The most pathogenic of these are the rhabdoviruses, a reovirus and three herpesviruses. Cyprinid herpesviruses can cause significant economic losses in aquaculture, and some of these viruses are oncogenic. The three herpesviruses are closely related but cause distinctly different diseases. Fish pox, caused by cyprinid herpesvirus 1 (CyHV-1), is one of the oldest known fish diseases, being recorded as early as 1563. It takes the form of a hyperplastic, epidermal papilloma on common carp. Cyprinid herpesvirus 2 (CyHV-2) is causative agent of herpesviral hematopoietic necrosis (HVHN). The herpesvirus was first isolated from cultured goldfish in Japan. It causes a severe epizootic but no external clinical signs were apparent on affected fish. One of the most economically important and researched viral diseases of carp is koi herpesviral disease caused by cyprinid herpesvirus 3 (CyHV-3). The aim of this paper is to present the current knowledge on herpesvirus diseases of the cyprinids.

Humoral immune response to repeated lumpy skin disease virus vaccination and performance of serological tests

BACKGROUND

In the presented study we investigated the development of the humoral immune response against LSDV during the process of re-vaccination of cattle over a time span of 5 months. In addition, the performance of different serological techniques for antibody detection against LSDV was compared. For sample collection, an area without previous LSD outbreak reports in Serbia was selected. Seventy-nine cattle from twenty farms vaccinated in 2016 and re-vaccinated in 2017 were included in the study. Two farms from the same area with good calving management were selected for investigation of passive LSDV antibody transfer from vaccinated mothers to new-borne calves.

RESULTS

All investigated cattle were healthy on the day of vaccination and during the whole study. Swelling at the injection site or other side effects of vaccination did not occur after re-vaccination in the study. Detection of LSD-specific antibodies was performed with the standard serological methods VNT and IFAT as well as a commercially available Capripox double antigen multi-species-ELISA. Capripoxvirus-specific antibodies were detected 46 to 47 weeks after vaccination in 2016, with VNT in 35.06% and with IFAT and ELISA in 33.77%. A secondary response was observed in all three tests 1 month after re-vaccination with a significant increase in seropositive animals compared to the results before re-vaccination. With all applied serological methods, the number of animals testing positive was significantly higher at 1 and 5 months post re-vaccination than before re-vaccination. No significant statistical difference (p > 0.05) was observed between the results of all three tests used. The sensitivity and specificity of ELISA was estimated to be SeELISA 91% and SpELISA 87% calculated by the results of VNT and SeELISA 88% and SpELISA 76% calculated by the results of IFAT. Passive antibody transfer from vaccinated mothers to new-born calves was investigated at 14 days after birth. Discrepancies for the detection of LSDV specific antibodies between cows and newborn calves at the age of 14 days were observed in VNT and IFAT, but not in ELISA.

CONCLUSION

Of all tests used the commercially available ELISA shows to be the most useful for high throughput analysis compared to VNT or IFAT.

Emerging viral diseases of cyprinids

The intensive aquaculture remains the world’s fastest growing sector producing food of animal origin. In fact, it is the only animal food-producing sector growing faster than the human population, and provides an acceptable supplement to and substitute for wild fish. A number of cyprinid diseases have emerged globally and their study has become increasingly important. The expansion of aquaculture, which has relied heavily on the movement of animals and farming species new to aquaculture, has been paralleled with disease emergence. In the last few years several emerging or re-emerging fish diseases have been detected in cyprinid fish populations in Serbia. In this paper, the authors overview the major viral threats for cyprinid fishes in Serbia

Some adverse events following immunization in veterinary medicine

Vaccines are a very effective tool for the prevention and eradication of infective diseases in both veterinary and human medicine. Although for safety reasons, vaccines undergo very strict controls before being placed on the market, the risk of adverse reactions is not eliminated. According to the World Health Organization (WHO), adverse event following immunization (AEFI) is any untoward medical occurrence that follows immunization and which does not necessarily have a causal relationship with the usage of the vaccine. Adverse reactions may arise as a direct consequence of immunization due to the specificity of the vaccine itself, the quality of the vaccine or the immunization errors. In addition, adverse reactions may also be the result of a coincidental relationship between the effect and immunization. However, biological mechanisms of AEFI are very complex. During the mass vaccination campaigns, when a large number of animals are vaccinated in a short period of time, adverse reactions are expected to be the most frequently reported. In Serbia, livestock is currently being vaccinated against Lumpy Skin Disease, Bluetongue, and Classical swine fever.

Molecular detection of black queen cell virus and Kashmir bee virus in honey

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.

High Abundance and Genetic Variability of Atypical Porcine Pestivirus in Pigs from Europe and Asia

Atypical porcine pestivirus (APPV) was recently reported to be associated with neurologic disorders in newborn piglets. Investigations of 1,460 serum samples of apparently healthy pigs from different parts of Europe and Asia demonstrate a geographically wide distribution of genetically highly variable APPV and high APPV genome and antibody detection rates.

Bovine viral diarrhea virus infection in wild boar

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.

EPIZOOTIOLOGICAL SITUATION OF АFRICAN SWINE FEVER IN EUROPE

African swine fever (ASF) is a viral disease of domestic pigs and wild boar. Due to the very serious socioeconomic consequences, the disease isone of the most important ones nowadays. African swine fever is an enzootic disease in many countries in Sub-Saharan Africa, in Sardinia, and TransCaucasus countries. Aft er its occurrence in Georgia in 2007, ASF spread to Armenia and Russian Federation, and in 2008. to Azerbaijan. Since then,its progressive moving toward the west has been recorded. Despite the number of undertaken preventive and control measures in the EuropeanUnion (EU), ASF has been still spreading. During 2017, the disease has been reported in domestic pigs in Estonia, Italy-Sardinia, Latvia, Lithuania,Poland, Romania, and Ukraine. ASF cases in domestic pigs have also been reported in Moldova in 2017. Th e number of diagnosed cases in wild boarin 2017 is much higher than in domestic pigs. ASF outbreak in wild boar in the Czech Republic well describes the possible viral „jump“ into a newregion. Th e source of infection hasn’t been confi rmed yet, but it is common that such leaps are due to either swill feeding or improperly disposal of food rather than to the animal movements. Since the lack of eff ective vaccine makes eradication even more diffi cult, the prevention of viral entry into the new areas is of the most importance. With the same aim, since 2011. the surveillance of ASF has been implemented in Serbia.

Polyarthritis in Goat-Kids Caused by Streptococcus Equi Subspecies Zooepidemicus

Infectious arthritides in goats is mainly caused by mycoplasmas and Caprine Arthritis- Encephalitis virus (CAEV). Streptococcus equi subspecies zooepidemicus (S. zooepidemicus) is a member of Lancefield group C beta-hemolytic streptococcus that commonly colonizes the mucous membranes of healthy equids which is also capable to induce different pathological conditions in many animal species. In this paper we described a case of polyarthritis in four Alpine goat-kids caused by S. zooepidemicus. Goat-kids originated from a farm where sheep, llamas, shepherd dogs, cows and horses were kept with goats. During the external examination of carcasses, crusts and discrete hyperemia were seen on the earlobes beneath the ear tag, as well as swollen joints. Necropsy findings included severe fibrinous polyarthritis in all four examined kids. Shoulder, knee and hip joints were affected. From all affected joints S. zooepidemicus was isolated. Neither Mycoplasma spp. nor CAEV genome were detected from the affected joints. Most likely the goatkids were infected with S. zooepidemicus through the lesions on earlobes which were made after the tagging. As a possible source of bacteria, we recognized the horses and dogs. Due to the lack of any signs of illness in other animal species on the farm, as well as negative pathomorphological findings in other organs, we assumed that the isolated strain is highly adapted to goat-kids. Our report is the first described case of polyarthritis in goat-kids caused by S. zooepidemicus.

Isolation and Molecular Detection of Bovine Parainfluenza Virus Type 3 in Cattle in Serbia

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.

Prevalence of Bovine herpesvirus type 4 in aborting dairy cows

Bovine herpesvirus type 4 (BHV-4) is related to many different conditions: infertility, postpartal metritis, vulvovaginitis, mastitis, encephalitis, calf pneumonia, keratoconjunctivitis, cutaneous lesions, digital dermatitis and abortion. In this study a retrospective PCR examination of 100 extracted DNA samples from aborting cows was performed in order to determine: prevalence of BHV-4 in abortive cattle, whether coinfections BHV-4 with other abortifacient pathogens are present in the same sample and to determine the month of gestation when BHV-4 associated abortions were detected. Out of 100 examined samples, the BHV-4 genome was detected in 21 samples (21%). In two samples we detected coinfection of BHV-4 with bovine viral diarrhea virus (BVDV) and in one withNeospora caninum. Most of the BHV-4-associated abortions were detected during the seventh month of gestation. It was concluded that an active BHV-4 infection was present among cows that aborted on the farms examined. The high prevalence of the BHV-4 genome in abortion material suggests that this virus may have cause the abortions. Further studies and examinations are needed to establish causative connection between presence of BHV-4 and abortion.

BLUETONGUE DISEASE - EPIZOOTIOLOGY SITUATION IN SERBIA IN 2015, DIAGNOSIS AND DIFFERENTIAL DIAGNOSIS

Bluetongue disease is non-contagious, vector borne, viral disease mainly of sheep but also of other domestic and wild ruminants. Bluetongue virus (BTV) belongs to the family Reoviridae, genus Orbivirus and is characterized by segmented double-stranded RNA. Virus is transmitted from one to another susceptible animal by hematophagous insects of the genus Culicoides. According to offi cial data, between 2002 and 2014, Serbia has belonged to BTV free countries. Aft er that, the fi rst outbreak occurred in August 2014. Th e last case was reported in December of the same year. During 2015, 74 samples were examined for exclusion of bluetongue disease: 8 in cattle, 65 in sheep and one in goat. In order to detect viral genome, 73 blood samples and one tissue sample were examined by reverse transcription - polymerase chain reaction (RT-PCR). None of tested samples was confi rmed to be BTV positive. Following the Instruction of the Ministry of Agriculture and Environmental Protection - Veterinary Directorate, monitoring program for Bluetongue disease in Serbia started from October 2015. The program consists of insect identifi cation and detection of viral genome in Culicoides spp. by RT-PCR assay. Of the 80 samples that were received during the program realization in 2015, only four, which were collected during late autumn, have contained insects of Culicoides spp. In none of them, BTV was detected. For diff erential diagnosis, 65 ovine blood samples were examined for the presence of viruses of contagious ecthyma, sheep and goat pox as well as eight bovine blood samples were tested for viruses of bovine viral diarrhea, infectious bovine rhinotracheitis / pustular vulvovaginitis and malignant catarrhal fever. Th e samples were analyzed using molecular methods (PCR and RT-PCR). Only two bovine blood samples gave positive reaction for the presence of bovine viral diarrhea virus.

Molecular Detection of PCV2 And PPV in Pigs in Republic of Srpska, Bosnia and Herzegovina

The presence of porcine circovirus 2 and porcine parvovirus was examined in forty clinical samples of spleen, lymph nodes and lungs originating from non-vaccinated swine by polymerase chain reaction. All animals were reared in extensive livestock farming systems in different geographical districts of Republic of Srpska, Bosnia and Herzegovina. Porcine circovirus 2 DNA was detected in four lymph node and two spleen samples (15%), while porcine parvovirus DNA was identified in five lymph node samples (12.5%). The presence of both viruses was detected in three lymph node samples (7.5%). Partial nucleotide sequence of ORF1 gene of 2 porcine circovirus 2 and VP2 gene of 2 porcine parvovirus isolates was determined. The nucleotide sequences of two PCV2 isolates from RS-BIH included in phylogenetic typing are similar and cluster together with the strain Mantova isolated from domestic pigs in Italy, strains DE006-14 and DE222-13 isolated from pigs in Germany as well as with the strain Jvnan isolated from pigs in China. Also, analyzed PCV2 isolates were partially similar to the strain NIV-C SRB isolated from pigs in Serbia. The nucleotide sequences of two PPV isolates that were included in phylogenetic typing showed a high level of similarity with the strain Challenge isolated from pigs in UK, strain Kresse isolated from pigs in USA and strains 77 and LZ isolated from pigs in China.

SEARCHING FOR SOLUTIONS IN AQUACULTURE: AQUAPONICS

Aquaponic production combines intensive production with waste recycling and water conservation. Aquaponic join recirculating aquaculture with hydroponics to use nutrient waste from aquaculture as an input to plant growth. Traditional aquaculture systems treat or dispose nutrient-rich wastewater. In aquaponics, the waste products from the fish are converted by a bio-fi lter into soluble nutrients which are absorbed by the plants, and allow “clean” water to be returned back to the fish. Thus, it produces valuable fish protein with a minimal pollution of fresh water resources, while at the same time producing horticultural crops. Fish in aquaponic production systems can be raised in ponds, tanks, or other containers. Plants are grown separately in hydroponic tanks, submerged in water but suspended in gravel, sand, perlite, or porous plastic films, as well as on floating rafts. Systems vary greatly in design and construction, but most perform the following key functions: finfish and plant production, removal of suspended solids, and bacterial nitrification. This review discusses applications, effects and perspective of aquaponics.

DETECTION OF AEROLYSIN (aerA) GENE IN AEROMONAS HYDROPHILA STRAINS ISOLATED FROM DISEASED CARP

Bacterial septicemia caused by motile aeromonads is common infection in the intensive fish production. Aeromonas (A.) hydrophila is often present in fish populations. Ubiquitous distribution of these bacteria in the aquatic environment, and the stress caused by intensive breeding are predisposing factors for the occurence of the disease. A. hydrophila is considered a major cause of septicaemia caused by motile aeromonads. Several A. hydrophila extracellular products (ECP) are considered as important factors in pathogenesis, primarily aerolysin (aerA), the extracellular lipase, cytolytic enterotoxin, hemolytic toxin and extracellular proteases. PCR detection of aerolysin (aerA) is considered a reliable method of identifying potentially pathogenic Aeromonas strains. In spring 2012, after a sudden increase in water temperature, disease occured in common carp population in one fish farm in Serbia. Five specimens of the one-year-old carp with clinical symptoms of motile aeromonas septicaemia were used for isolation of the bacteria. Identification of A. hydrophila was done on the basis of morphological, physiological, cultural and biochemical characteristics. PCR amplification of DNA from A. hydrophila isolates revealed presence of aerolysin (aerA) gene in all examined A. hydrophila isolates from carp with motile aeromonas septicaemia.