Harnessing Attenuation-Related Mutations of Viral Genomes: Development of a Serological Assay to Differentiate between Capripoxvirus-Infected and -Vaccinated Animals

Sheeppox, goatpox, and lumpy skin disease caused by the sheeppox virus (SPPV), goatpox virus (GTPV), and lumpy skin disease virus (LSDV), respectively, are diseases that affect millions of ruminants and many low-income households in endemic countries, leading to great economic losses for the ruminant industry. The three viruses are members of the Capripoxvirus genus of the Poxviridae family. Live attenuated vaccines remain the only efficient means for controlling capripox diseases. However, serological tools have not been available to differentiate infected from vaccinated animals (DIVA), though crucial for proper disease surveillance, control, and eradication efforts. We analysed the sequences of variola virus B22R homologue gene for SPPV, GTPV, and LSDV and observed significant differences between field and vaccine strains in all three capripoxvirus species, resulting in the truncation and absence of the B22R protein in major vaccines within each of the viral species. We selected and expressed a protein fragment present in wildtype viruses but absent in selected vaccine strains of all three species, taking advantage of these alterations in the B22R gene. An indirect ELISA (iELISA) developed using this protein fragment was evaluated on well-characterized sera from vaccinated, naturally and experimentally infected, and negative cattle and sheep. The developed wildtype-specific capripox DIVA iELISA showed >99% sensitivity and specificity for serum collected from animals infected with the wildtype virus. To the best of our knowledge, this is the first wildtype-specific, DIVA-capable iELISA for poxvirus diseases exploiting changes in nucleotide sequence alterations in vaccine strains.

American Foulbrood—Old and Always New Challenge

American foulbrood (AFB) is exclusively an infectious disease of honey bee larvae (Apis mellifera) and their subspecies that is spread easily and rapidly and is often present in apiaries. Due to the resistance and pathogenicity of the bacterial causative agent of the disease, which has considerable epizootiological and economic significance for beekeeping, AFB was classified as a highly dangerous, infectious animal disease by the World Organization for Animal Health (WOAH). Considering the severity of the infection, a frequent occurrence, rapid and easy spread, epizooty and enzooty are common. We tried to present an overview of the latest information related to AFB through several chapters. In addition to the latest data on the etiology of the causative agent, the most important elements of the clinical signs of the disease are also listed. Along with an overview of classic microbiological and the latest molecular methods of diagnosis, we also discuss AFB treatment from its differential diagnostic aspect. We hope that through demonstrating the mentioned preventive measures and measures of good beekeeping practice, the review will contribute to the preservation of the health of bees and therefore the overall biodiversity of the planet.

Highly Pathogenic Avian Influenza H5N8 Outbreak in Backyard Chickens in Serbia

In winter 2016/2017, the highly pathogenic avian influenza virus H5N8 was detected in backyard poultry in Serbia for the first time. The second HPAI outbreak case in backyard poultry was reported in 2022, caused by subtype H5N1. This is the first study that documents the laboratory identification and pathology associated with highly pathogenic avian influenza in poultry in Serbia during the first and second introduction waves. In both cases, the diagnosis was based on real-time reverse transcriptase PCR. The most common observed lesions included subepicardial hemorrhages, congestion and hemorrhages in the lungs, and petechial hemorrhages in coelomic and epicardial adipose tissue. Histologically, the observed lesions were mostly nonpurulent encephalitis accompanied by encephalomalacia, multifocal necrosis in the spleen, pancreas, and kidneys, pulmonary congestion, and myocardial and pulmonary hemorrhages. In H5N8-infected chickens, immunohistochemical examination revealed strong positive IHC staining in the brain and lungs. Following these outbreaks, strict control measures were implemented on farms and backyard holdings to prevent the occurrence and spread of the disease. Extensive surveillance of birds for avian influenza virus did not detect any additional cases in poultry. These outbreaks highlight the importance of a rapid detection and response system in order to quickly suppress outbreaks.

Development of multiplex PCR based NGS protocol for whole genome sequencing of West Nile virus lineage 2 directly from biological samples using Oxford Nanopore platform

West Nile virus (WNV) can affect humans, birds, horses and another mammals, causing asymptomatic infection, mild febrile disease, neurological and systematic disease and death. In order to gain insight into the prevalence of WNV, a monitoring program has been established in the Republic of Serbia. Whole genome sequencing is essential for the molecular epizootiological analysis of virus entry and transmission routes, especially in high-risk regions. This paper describes the development of a multiplex PCR based NGS protocol for whole genome sequencing of WNV lineage 2 directly from biological samples using Oxford Nanopore (ONT) platform. The results obtained using this platform, confirmed by Sanger sequencing, indicate that this protocol can be applied to obtain whole sequences of the WNV genome, even when the virus concentration in the sample is medium, Ct value is approximately 30. The use of this protocol does not require prior virus isolation on cell culture nor the depletion of host nucleic acids.

Genomic Analysis of Multidrug-Resistant Salmonella enterica Serovar Kentucky Isolates from Humans, Turkey, and Food in the Republic of Serbia

Owing to the emerging resistance to antimicrobials in Salmonella Kentucky isolates around the globe, the genomic comparison of all the registered multidrug-resistant Salmonella Kentucky isolates in Serbia (five from humans, one from turkey flock, and one from meat) was done. Most of the isolates were isolated from patients returning from Egypt or Tunisia or originated from imported turkey flock and turkey meat. The comparative analysis of resistance and virulence genes was done. All isolates belonged to sequence type-ST198 and were resistant to ciprofloxacin (Cip). The resistance to Cip was mediated by target mutations of the gyrA and parC genes, which encode topoisomerase I and II, respectively. Multidrug-resistant phenotype to aminoglycosides, β-lactam antibiotics, sulfonamides, and tetracyclines was detected in five isolates. However, none of the isolates was pan-resistant to antimicrobials. The number of single nucleotide polymorphisms between isolates varied from 8 to 43 and phylogenomics revealed the genetic proximity of the human isolate 10475/11 and the turkey meat isolate 5264/14, indicating a possible meat-to-human transfer. All isolates belonged to the main Salmonella Kentucky MDR lineage, carrying the Salmonella genomic island 1 (SGI1-K) subtype. The SGI1-K of Serbian isolates showed mosaicism attributed to rapid intraclonal evolution. Many virulence factors were detected in all the isolates, including SPI-1, SPI-2, SPI-3, SPI-4, SPI-5, SPI-9, and C63PI. Although Salmonella Kentucky has rarely been isolated from humans, food, and animals in Serbia, further surveillance is needed to diminish the risk of the spreading of resistant clones and their meat-to-human transmission.

First Report of Alveolar Hydatid Disease (Echinococcus multilocularis) in a Golden Jackal (Canis aureus)

BACKGROUND

Alveolar hydatid disease caused by the tapeworm Echinococcus multilocularis is a parasitic disease present in the northern hemisphere. Echinococcus multilocularis is a parasite of canid and felid carnivores as definitive hosts, and small mammals, particularly rodents as intermediate hosts. Other animal species and humans can be aberrant intermediate hosts for this parasite. It is known that besides acting as definitive hosts, domestic dogs can rarely become infected with the larval form of E. multilocularis and develop alveolar echinococcosis; however, a role of wild canids as aberrant intermediate hosts has not been documented until now. To the best of our knowledge the present paper provides the first description of alveolar hydatid disease in a golden jackal (Canis aureus).

CASE PRESENTATION

Necropsy of the yearling female animal found a large, round, tumor-like mass, 20 cm in diameter, with a rough, multilobulated surface in the abdominal cavity, connected to the liver and omentum. On the cut surface this tumor-like lesion was multicystic, with a number of locular cavities filled with a clear yellowish to orange watery fluid and a large area of necrosis in the central part of the mass. Histopathology revealed multiple cystic spaces separated by fibrous sheaths and inflammatory cells-lymphocytes, plasma cells, neutrophil and eosinophil granulocytes. The cysts contained either pale, hyaline, eosinophilic laminar and occasionally amorphous, acellular, PAS-positive structures, or metacestodes with invaginated protoscolices. In several cysts round calcified bodies (calcareous corpuscles) were noted. Microscopic examination showed everted and inverted protoscolices which were attached to fragments of the brood capsule or free in hydatid fluid. By comparing consensus nucleotide sequence of 457 bp obtained by PCR reaction with sequences deposited in NCBI GenBank it is determined that it was 100% identical with E. multilocularis sequences under accession numbers MH259778.1, MH259776.1, AB668376.1, EU704124.1 and AB018440.2.

CONCLUSIONS

The present paper provides a proof that the golden jackal, besides being a definitive host, can also serve as the aberrant intermediate host for E. multilocularis.

HONEYBEE VIRUSES PRESENCE IN SERBIAN APIARIES: A REVIEW

The honey bee Apis mellifera is an important beneficial insect recognized by production of honeybee products, having an important role in agricultural production through pollination, and play an equally crucial role in conserving the biodiversity in many natural ecosystems. According to available literature data, in the last more than 20 years, dramatic honey bee winter colony losses have been reported frequently all over the world that could have a direct influence on human food resources and can affect not only apiculture or agriculture, but also has an anthropological threats. One among many reasons for global bees-decline phenomenon is the influence of many viruses on honeybees’ health. Until today, in total, 36 viruses is detected in honey bees, and for many of them still without known pathogenicity on honeybees’ health. However, it is well known that some of these viruses like Acute Bee Paralysis Virus (ABPV), Chronic Bee Paralysis Virus (CBPV), Deformed Wing Virus (DWV), Black Queen Cell Virus (BQCV), Sacbrood Virus (SBV), Kashmir Bee Virus (KBV), Israeli Acute Paralysis Virus (IAPV), Slow bee paralysis virus (SBPV), Varroa destructor virus (VDV1) and some others has direct or indirect influence on individual honeybee or on whole honeybees colony health. In this paper the review of existing literature data on the presence, prevalence and characterization of honeybee viruses detected in honeybee colonies and apiaries from different regions in Serbia from first detection of their presence in 1986 till nowadays is presented and discussed.

Validation of TaqMan-Based Assays for Specific Detection and Differentiation of Wild-Type and Neethling Vaccine Strains of LSDV

Lumpy skin disease (LSD) is an important animal disease with significant health and economic impacts. It is considered a notifiable disease by the OIE. Attenuated strains of LSDV have been successfully used as vaccines (LAV) but can also produce mild or systemic reactions. Vaccination campaigns using LAVs are therefore only viable if accompanying DIVA assays are available. Two DIVA qPCR assays able to distinguish Neethling-based LAVs and wild-type LSDV were developed. Upon validation, both assays were shown to have high sensitivity and specificity with a diagnostic performance comparable to other published DIVA assays. This confirmed their potential as reliable tools to confirm infection in animals during vaccination campaigns based on Neethling vaccine strains.

Subtyping Blastocystis in pigs and humans revealed unusual avian-specific subtype ST6 in humans in Serbia

Blastocystis is a common protist colonizing the gastrointestinal tract of humans and various animals. The first subtyping of Blastocystis isolates in pigs and humans in Serbia revealed unusual avian-specific subtype ST6 in humans. In total, 48 pig faecal specimens collected on seven pig farms and 50 human faecal specimens positive to Blastocystis by microscopic examination were selected for the study. Eleven randomly selected PCR-positive pig samples and 10 samples from human patients (with gastrointestinal complaints) were subjected to SSU rDNA sequencing. Three subtypes were identified (ST3, ST5 and ST6) by phylogenetic analysis. ST5 was found in all pig samples; while in human samples, we detected ST3 and ST6. The latter subtype is relatively uncommon in Europe and highly adapted to avian hosts; therefore, the possibility of sporadic zoonotic transmission to human patients should not be ignored.

DNA-based molecular identification of Urnula mediterranea (Ascomycota, Pezizales) collected in Central Serbia

Molecular systematics is a branch of systematics that analyzes genetic markers for the classification of organisms. Genetic markers include target sequences of molecules DNA, RNA, and amino acids. The most often used genetic markers are DNA markers, localized on DNA molecules. The study aim was DNA-based molecular identification of species Urnula mediterranea (M. Carbone, Agnello & Baglivo) M. Carbone, Agnello & P. Alvarado (2013), by using molecular systematics methods. This species was recently discovered for the first time in Central Serbia and determined only based on morphological characteristics. For the first time, U. mediterranea sampled in Serbia, was identified with DNA molecular markers. Extraction of DNA molecules was performed from the fruiting body of U. mediterranea. ITS region and the part of the gene for 28S rRNA were amplified and sequenced by the Sanger method. Comparing the analyzed sequences with the sequences from the database, a match of 99.72% was found for the ITS region and 100% for the part of the gene for 28S rRNA. By molecular identification, it has been established that the sample belongs to the species U. mediterranea. Both analyzed DNA sequences of U. mediterranea were deposited into the NCBI database.

Twenty-five-year study of Nosema spp. in honey bees (Apis mellifera) in Serbia

A total of 7386 samples of adult honey bees from different areas of Serbia (fifteen regions and 79 municipalities) were selected for light microscopy analysis for Nosema species during 1992–2017. A selection of honey bee samples from colonies positive for microsporidian spores during 2009–2011, 2015 and 2017 were then subjected to molecular diagnosis by multiplex PCR using specific primers for a region of the 16S rRNA gene of Nosema species. The prevalence of microsporidian spore-positive bee colonies ranged between 14.4% in 2013 and 65.4% in 1992. PCR results show that Nosema ceranae is not the only Nosema species to infect honey bees in Serbia. Mixed N. apis/N. ceranae infections were detected in the two honey bee samples examined by mPCR during 2017. The beekeeping management of disease prevention, such as replacement of combs and queens and hygienic handling of colonies are useful in the prevention of Nosema infection.

The prevalence of pathogenic forms of Leptospira in natural populations of small wild mammals in Serbia

The greatest epidemiological significance of leptospirosis in Europe comes from the fact that it is the most widespread zoonosis in the world. However, epizootiological data, especially information on maintenance hosts such as small wild mammals, are largely missing. To fill this gap in data in Serbia, we used RT-PCR for the detection of pathogenic Leptospira species and analysed 107 animals belonging to six species of small wild mammals (Apodemus agrarius, Apodemus flavicollis, Microtus arvalis, Myodes glareolus, Microtus subterraneus and Sorex araneus) collected from two localities. The animals from the first locality that was situated in a tourist area, were collected for four consecutive years (2014-2017). We found persistent incidence of infection from year to year ranging from 6.67% to 78.57%. The average frequency of infected animals was 33.3% with the highest frequency in 2014, the year characterised by a very high number of flooding days. All animals proved to be infected with pathogenic Leptospira species that were collected from the second locality situated in an agricultural area in a single year, 2014. The findings show a variable but constant presence of pathogenic Leptospira species in populations of small wild mammals in the studied areas, which indicates the need for constant monitoring.

Are golden jackals (Canis aureus) definitive hosts for Angiostrongylus vasorum?

Angiostrongylosis caused by Angiostrongylus vasorum is an emerging disease in Europe. Recent reports have shown that, besides the red fox (Vulpes vulpes) recognized as the main definitive host and reservoir for the parasite, the role of the definitive host can be taken by a range of mammals. We considered that, due to the rapid large-scale expansion of its populations in Europe, the golden jackal (Canis aureus) could assume an important role in the epidemiology of the disease. The aim of the investigations was to explore the role of the golden jackal as the definitive host for A. vasorum. Sixty-three golden jackals, legally hunted in lowlands around the Danube River in Serbia recognized as the core area of the species' distribution in Europe, were subjected to patho-morphological and parasitological examination. The adult forms of A. vasorum were detected in the pulmonary arteries in six golden jackals with gross lesions manifested in the lungs. The finding of first stage larvae (L1) of A. vasorum in microscopic smears of the lung tissue altered by infection, which was consistent with the presence of adult parasites and manifestation of gross lesions in the lungs, confirms the successful reproduction of the parasite in the golden jackal. Migration of L1 from the blood vessels to the airways was confirmed by histopathology and, subsequently, their shedding was demonstrated by the Baermann method. The results support the hypothesis that the golden jackal acts as a suitable definitive host for A. vasorum. As a definitive host with a large-scale expansion of its populations in Europe, the golden jackal may be an important part of the parasite's host repertoire by spreading the parasite into previously non-endemic areas and by being an additional definitive host in endemic areas of vulpine angiostrongylosis.

Epizootic features and control measures for lumpy skin disease in south-east Serbia in 2016

Lumpy skin disease (LSD) is an infectious disease of cattle caused by virus of the Capripoxvirus genus (LSDV), family Poxviridae. Until 2015, it had not appeared in the Balkans. In June 2016, LSD spread throughout Serbia. This study analyses the first LSD occurrence, epizootic features, applied diagnostic procedures and control measures in five districts in south-east Serbia (Pcinja, Jablanica, Pirot, Toplica and Nisava). In total, there were 225 LSD outbreaks reported in Serbia, out of which 189 (84%) were located in the study area. The highest number of outbreaks was registered in Pcinja district (169), where LSD was first registered. The median distance and time between the nearest previous outbreak sites were calculated (4.32 km and 9 days). The median altitude of outbreak locations was 992 m with more than 90% above 500 m (p ≤ 0.001). The average herd morbidity rate in the study area was 13.6% and the herd mortality rate was recorded only in Pcinja (0.5%) and Jablanica (1.6%) districts. Samples taken from the cattle suspected to LSD were subjected to real time PCR analysis. Out of 233 samples tested for LSDV 132 (56.7%) were positive. The LSDV genome was identified in skin nodules (85.4%), blood (72.7%) and nasal swabs (62.5%). Phylogenetic analysis indicated that the LSDV strain circulating in Serbia fell within the cluster of field LSDV found worldwide. In response to the LSD epizootic, animal trade and movement were prohibited, complete stamping out, disinfection, disinsection and an entire bovine population vaccination using the homologous Neethling live attenuated vaccine (OBP, South Africa) were conducted. A month and a half after the completion of the vaccination campaign, the LSD epizootic was stopped, and no new cases have been reported since.

Overview of diagnostic tools for Capripox virus infections

Capripox viruses are the causative agents of important animal diseases in cattle (Lumpy Skin Disease), sheep (Sheeppox) and goats (Goatpox) with severe socio-economic impact in case of wide scale outbreaks. Therefore there is a constant need for adequate diagnostic tools. The assays must be fit-for-purpose to identify the virus quickly and correctly and to be useful for surveillance and monitoring at different stages of an epidemic. Different diagnostic performance characteristics are required depending on the situation and the test purpose. The need for high throughput, high specificity/sensitivity and the capability for differentiating field virus strains from vaccine strains drives the development of new and better assays preferably with an advantageous cost-benefit balance. This review aims to look at existing and new virological and serological diagnostic tools used in the control against diseases caused by Capripox viruses.

Flaviviruses at the territory of Serbia – present situation and challenges

The aim of this study is to summarize the data on the occurrence, presence and prevalence of some zoonotic flaviviruses, which have been actively circulating in the territory of the Republic of Serbia during past decade. The genus Flavivirus, family Flaviviridae,encompasses vector-transmitted viruses with zoonotic potential. The genus is comprised of more than 70 viruses transmitted to humans by mosquitoes and ticks. Some of those are associated only with human diseases (such as yellow fever and dengue fever), whereas others can cause diseases in both humans and animals. Animals are major reservoirs and primary hosts for the latter group. The virus transmission to other animal species or humans occurs via diverse vectors – mostly mosquitoes and ticks. A range of these virus species is widely distributed worldwide, especially in tropical and sub-tropical climatic zones. Some representatives of these species have only recently been identified at the territory of Republic of Serbia. This paper gives an evidence on the presence and distribution of West-Nile virus, tick-borne encephalitis (TBE) virus and Usutu virus that were conducted within the study in Serbia. The research pointed out the presence of recently detected West-Nile virus and Usutu virus as well as the current circulation of tick-borne encephalitis virus, for which only limited serological evidence on the presence of virus-specific antibodies in humans was available so far. In the aspect of public health, the full understanding of the importance of identification and prevalence of different flaviviruses still require further comprehensive entomologicalacarological, seroepidemiological, clinical and virological research. 

Clinical, epidemiological and epizootic features of a Q fever outbreak in the border region between Serbia and Montenegro

Introduction: Q fever is a zoonosis which commonly manifests as an acute febrile disease accompanied by pneumonia or hepatitis. The aim of this study was to reveal the reservoirs, sources and routes of infection relevant for the Q fever outbreak that occurred in the border region between Serbia and Montenegro. Methodology: A prospective study was conducted from 3rd to 23rd March, 2016 in Brodarevo, village near the Serbian-Montenegro border. The EU case definition for Q fever was applied and serological evidence of IgM and/or IgG antibody for phase II antigen Coxiella burnetii used for laboratory confirmation. Animal infection was proven by detection of specific biomarkers for Q fever by ELISA and Real-Time PCR. Results: In total, ten patients were registered with Q fever, giving an attack rate of 0.5% in the village. A severe form of disease with atypical pneumonia ended up with hospitalization of eight patients. Serological surveillance was conducted in 30 herds of the receptive animals in the outbreak area. Overall the anti-Coxiella antibody seroprevalence was 20.6%. Positive molecular findings (68.4%) accompanied with high seroprevalence (63.2%) were identified in a mini-farm of sheep and cattle in the nearby Orasac, these were considered to be active sources of infection. The most probable route of C. burnetii transmission was the inhalation of contaminated aerosols originating from infected animals. Conclusion: The main reservoirs for human Q fever at the border region between Serbia and Montenegro are infected cattle and ruminants. Adoption of a comprehensive strategy for disease prevention and control at the intergovernmental level is urgent.

Methodology and results of integrated WNV surveillance programmes in Serbia

Studies conducted during the past few years have confirmed active West Nile virus (WNV) circulation in Serbia. Based on these studies and the epidemiological situation, the Veterinary Directorate of the Ministry of Agriculture and Environmental Protection launched national WNV surveillance programmes in 2014 and 2015. The programmes encompassed the territory of Serbia and were conducted by the veterinary service in collaboration with entomologists and ornithologists. The objective of the programmes was early detection of WNV and timely reporting to the public health service and local authorities to increase both clinical and mosquito control preparedness. The WNV surveillance programmes were based on direct and indirect surveillance of the presence of WNV by the serological testing of initially seronegative sentinel horses and chickens as well as through viral detection in pooled mosquito and wild bird samples. The most intense WNV circulation was observed in all seven districts of Vojvodina Province (northern Serbia) and Belgrade City, where most of the positive samples were detected among sentinel animals, mosquitoes and wild birds. The West Nile virus surveillance programmes in 2014 and 2015 showed satisfactory results in their capacity to indicate the spatial distribution of the risk for humans and their sensitivity to early detect viral circulation at the enzootic level. Most of the human cases were preceded by the detection of WNV circulation as part of the surveillance programmes. According to the existing data, it can be reasonably assumed that WNV infection, now an endemic infection in Serbia, will continue to present a significant problem for the veterinary service and public health.

The Role of Myofibroblasts in Granulomatous Lymphadenitis in Pigs Naturally Infected with M. Avium Subsp. Hominissuis

The most important morphological characteristic of infections caused by M. avium subsp. hominissuis (MAH) is granuloma formation. The growth of mycobacteria is in accordance with anti-bacterial effector mechanisms of the host within granuloma. The most important cytokines for „orchestrating“the host defense are interferon γ (INF-γ), tumor necrosis factor α (TNF-α) and transforming growth factor β1 (TGF-β1). Myofibroblasts that make up a peripheral layer of granuloma largely express receptors for TGF-β1. This cytokine is believed to affect the induction of myofibroblast proliferation. The aim of this paper is to point out the importance of myofibroblasts in the formation and sustainability of granuloma during natural infection of pigs with M. avium subsp. hominissuis. Examinations have been performed on the samples of Lnn. jejunales, Lnn. ileocolici and Lnn. colici of 100 pigs with a positive tuberculin skin test. The molecular method confirmed the presence of a genome M. avium subsp. hominissuis. The microscopic examination of lymph node samples stained by the routine hematoxyilin-eosin (HE) method, showed the presence of granulomatous lymphadenitis. The method of double immunohistochemical staining revealed that myofibroblasts which express TGF-β1 receptor type I (TGF-β1RI) and α smooth muscle actin (α SMA) have an important role in the morphogenesis of granulomatous lymphadenitis in pigs infected with MAH.

Comparative pathomorphological, bacteriological and serological examination of broiler breeders and pheasants experimentally infected with Ornithobacterium rhinotracheale

The aim of the investigations was to determine the influence of Ornithobacterium rhinotracheale (ORT) on the development of pathomorphological lesions in the respiratory organs and on the health status of experimentally infected broiler breeders and pheasants from the rearing stage. There was no evidence of clinical signs in infected broiler breeder hens nor in the group of infected pheasants except for one bird in the latter group which exhibited slower movement and gasping. The frequency and intensity of pathomorphological lesions were higher in pheasants. The gross pathology findings were characterized mainly by redness of the mucosa of the upper respiratory tract and accumulation of mucous content in the nasal cavities, infraorbital sinuses, larynx and trachea. Histopathology confirmed the presence of inflammation of the upper respiratory tract. Lesions in the lungs included hyperaemia, granulomatous and fibrinous pneumonia. ORT was reisolated only from the group of infected pheasants. Reisolation was successful from the respiratory organs (trachea, larynx, infraorbital sinuses, and lungs) of eight out of 10 infected birds. The serological response in both species was characterized by rapid production of specific antibodies that reached a maximum level in the blood in the first week after experimental infection. The antibody titres decreased gradually and were maintained at a stable level until the 12th week after inoculation. Fourteen weeks post-inoculation specific antibodies could not be detected by enzyme-linked immunosorbent assay.

Prevalence of Genotypes That Determine Resistance of Staphylococci to Macrolides and Lincosamides in Serbia

Macrolides, lincosamides, and streptogramins (MLS) resistance genes are responsible for resistance to these antibiotics in Staphylococcus infections. The purpose of the study was to analyze the distribution of the MLS resistance genes in community- and hospital-acquired Staphylococcus isolates. The MLS resistance phenotypes [constitutive resistance to macrolide–lincosamide–streptogramin B (cMLSb), inducible resistance to macrolide–lincosamide–streptogramin B (iMLSb), resistance to macrolide/macrolide–streptogramin B (M/MSb), and resistance to lincosamide–streptogramin A/streptogramin B (LSa/b)] were determined by double-disc diffusion method. The presence of the MLS resistance genes (ermA, ermB, ermC, msrA/B, lnuA, lnuB, and lsaA) were determined by end-point polymerase chain reaction in 179 isolates of staphylococci collected during 1-year period at the Center for Microbiology of Public Health Institute in Vranje. The most frequent MLS phenotype among staphylococcal isolates, both community-acquired and hospital-acquired, was iMLSb (33.4%). The second most frequent was M/MSb (17.6%) with statistically significantly higher number of hospital-acquired staphylococcal isolates (p < 0.05). MLS resistance was mostly determined by the presence of msrA/B (35.0%) and ermC (20.8%) genes. Examined phenotypes were mostly determined by the presence of one gene, especially by msrA/B (26.3%) and ermC (14.5%), but 15.6% was determined by a combination of two or more genes. M/MSb phenotype was the most frequently encoded by msrA/B (95.6%) gene, LSa/b phenotype by lnuA (56.3%) gene, and iMLSb phenotype by ermC (29.4%) and ermA (25.5%) genes. Although cMLSb phenotype was mostly determined by the presence of ermC (28.9%), combinations of two or more genes have been present too. This pattern was particularly recorded in methicillin-resistant Staphylococcus aureus (MRSA) (58.3%) and methicillin-resistant coagulase-negative staphylococci (MRCNS) (90.9%) isolates with cMLSB phenotype. The msrA/B gene and M/MSb phenotype were statistically significantly higher in hospital-acquired than community-acquired staphylococci strains (p < 0.05). There are no statistically significant differences between staphylococci harboring the rest of MLS resistance genes acquired in community and hospital settings (p > 0.05). The prevalence of iMLSb phenotypes may change over time, so it is necessary to perform periodic survey of MLS resistance phenotypes, particularly where the D-test is not performed routinely.

Molecular Characterization of Multidrug-Resistant Escherichia coli Isolates from Bovine Clinical Mastitis and Pigs in the Vojvodina Province, Serbia

The aim of the study was to characterize multidrug-resistant (MDR) Escherichia coli isolates collected in Serbia from bovine clinical mastitis cases and diseased pigs, mainly with molecular methods. A total of 48 E. coli isolates was collected during the years 2013-2014, of which 22 were MDR and were included in further analysis. Phylogenetic typing showed that 17 isolates belonged to group A, while two isolates were classified in group B1 and a single one in group D. All isolates showed unique macrorestriction patterns. Phenotypic susceptibility testing revealed resistances of the isolates against up to 13 antimicrobial agents, including resistance to fluoroquinolones. A wide variety of resistance genes was detected by PCR amplification and sequencing of amplicons. Sequence analysis of the quinolone resistance determining regions of topoisomerase genes revealed mutations in gyrA, parC, and/or parE. Plasmid-mediated quinolone resistance genes were detected in two porcine (aac-6'-Ib-cr and qnrS, respectively) isolates and a single bovine (aac-6'-Ib-cr) isolate. Resistance genes were found to be located on conjugative plasmids in 16 cases, many of which conferred a multidrug resistance phenotype. In conclusion, the plentitude of resistance genes located on conjugative plasmids and integrons in E. coli from cows and pigs in Vojvodina, Serbia, pose a high risk for horizontal gene transfer in bacteria from livestock husbandry.

Real-Time PCR Assays for the Specific Detection of Field Balkan Strains of Lumpy Skin Disease Virus

Lumpy skin disease (LSD) is an important disease of cattle which is included in the OIE list of notifiable terrestrial animal diseases because of its great economic importance. The etiological agent is the Lumpy skin disease virus (LSDV).

In the control of LSD attenuated strains of LSDV and SPPV are successfully used as vaccine strains in infected areas. In the case of vaccination policy, due to the possibility of mild or systemic post-vaccination reactions in vaccinated animals, the application of diagnostic procedures that will rapidly and specifically differentiate LSDV field strains from LSD vaccine virus strains are extremely important. Rapidity in diagnostics and disposal of infected animals is one of the key factors in the prevention of spreading the disease.

In the presented study we have described the development and validation of two real-time TaqMan-PCR assays for a rapid, sensitive and specific detection of the virulent field LSDV strain currently circulating in the Balkan Peninsula. Specificity for the field strain and exclusivity for vaccine strains was tested on 171 samples from naturally infected and vaccinated animals.

The results of this study show that both developed real-time PCR assays are more sensitive than the conventional nested PCR in detecting field LSDV strains thus enabling rapid and high-throughput detection of animals infected with field strains of LSDV.

In conclusion, both KV-2 and FLI real-time PCR assays described in this study are simple, rapid, sensitive and suitable for routine use in a diagnostic laboratory and have the potential to replace conventional nested gel-based PCR assays as the standard procedure for the detection of field strains of LSDV in clinical samples.

PROPOSAL OF A PROGRAM FOR CONTROL, SUPPRESSION AND ERADICATION OF BOVINE VIRAL DIARRHEA VIRUS INFECTION IN CATTLE HERDS IN THE REPUBLIC OF SERBIA

Bovine Viral Diarrhoea (BVD) is a viral infection of cattle caused by Bovine Viral Diarrhoea Virus (BVDV). Th e most important source of infectionis persistently infected and sick cattle, but also other susceptible species. BVDV infection, except for cattle, occurs in sheep, pigs, goats and wild ruminants. Th ese animals can be reservoirs of the virus, and thus the source of infection. Th e greatest economic losses caused by BVDV infectionin cattle farming are the direct consequences of transplacental infection, as a result of foetal deaths, congenital malformations, neonatal and postnatal mortality, including mucosal diseases and slow growth and poor performance results of the surviving animals, as well as acute infections of respiratory and alimentary infections. Economic losses due to BVDV infection can be seen in a cattle herd even several years aft er the infection. Moreover, BVDV infection is considered as the third most important disease to cattle farming industry, immediately aft er rinderpest and the foot-and-mouth disease. Th e primary task of BVDV infection control is to prevent prenatal infection. This procedure includes the determination and elimination of persistently infected (PI) animals from the herd. Aft er the removal of these animals, great attention must be paid to introducing new animals into the herd and preventing the occurrence of transplacental infection. On the basis of existing data and real suppositions about the distribution of BVDV infection in the territory of Serbia, the great economic damages it causes, as well as the general tendency to resolve problems in European states, and for the competitiveness of our farmers and food industries in the production of milk, meat or breeding material after joining the EU market, it is necessary to draft legal regulations in the control of this bovine viral disease in Serbia. The mentioned control could be based on the voluntary BVDV eradication program on herd’s level in the beginning and on establishing herds with BVDV free status. Certifi cation of BVDV free status of herd will be done by Veterinary Directorate, and the register of herds with BVDV free status could be “on line” available and maintained by the Veterinary Directorate. The essence of this proposal, a volunteer program of establishing herds with BVDV free status, is based on several steps or phases, which includes frequent diagnostic testing, removal of PI animals from the herd and the introduction of strict biosecurity measures.

Characterization Of Tetracycline Resistance Of Salmonella Enterica Subspecies Enterica Serovar Infantis Isolated From Poultry In The Northern Part Of Serbia

Resistance to tetracycline was studied in Salmonella Infantis isolated from 28 poultry farms in the Northern part of Serbia (The Autonomous Province of Vojvodina). A total of 18 isolates were resistant to nalidixic acid (NAL) and tetracycline (TET). The minimal inhibitory concentration (MIC) to TET, ranged from 1-256 mg/L. Namely, 13 isolates exhibited MIC to TET at 256 mg/L, in four of the isolates, the MIC was 128 mg/L and one isolate had MIC 64 mg/L. Ten isolates were exhibiting a MIC of 1mg/L. It was evident that Salmonella Infantis had also spread to breeders and layers. In this work, we detected the tetA gene and the corresponding tetR gene (encoding the repressor protein) as well as the truncated transposon Tn1721, which are responsible for the resistance to TET. The presence of the non conjugative transposons from the conjugative plasmid has facilitated the spread of resistance to TET in Salmonella. It was concluded that higher biosecurity practice in poultry farming presents the best option to eliminate infections caused by Salmonella spp. from poultry flocks in Serbia. A rational use of antimicrobials is necessary to prevent any further spread of Salmonella Infantis resistant clones.

Simultaneous detection of vaccinal and field infectious bursal disease viruses in layer chickens challenged with a very virulent strain after vaccination

Infectious bursal disease virus is an important poultry pathogen. It is distributed worldwide and causes significant economic losses. In this study, a system was adopted for the simultaneous monitoring of vaccine and virulent strains using reverse transcription polymerase chain reaction (RT-PCR). After the decay of maternal antibodies, chickens were vaccinated at the age of 37 days with a virus of intermediate virulence and challenged at 5, 10 and 14 days post vaccination (dpv). The challenge was done with IBDV strain CH/99. Sequencing of the hypervariable region of VP2 has shown that CH/99 belongs to the very virulent group of viruses. The vaccine virus could be found in the bursa of Fabricius, spleen, thymus and bone marrow until 24 dpv. The CH/99 challenge virus was found in the bursa and lymphoid organs when chickens were challenged at 5 and 10 dpv. When challenge was performed at 14 dpv, the pathogenic virus could not be found in the bursa and other lymphoid organs.

Q fever outbreak in the village of Noćaj, Srem county, Vojvodina province, Serbia, January to February 2012

From 27 January to 10 February 2012, a total of 43 cases of Q fever were notified in the village of No?aj, Srem county, Autonomous Province of Vojvodina, Republic of Serbia. Q fever was laboratory confirmed in 37 notified cases. Alhough, the outbreak is considered over, the outbreak investigation is still ongoing in order to identify aetiologic factors relevant for this outbreak.

Q fever outbreak in the village of Noćaj, Srem County, Vojvodina Province, Serbia, January to February 2012

From 27 January to 10 February 2012, a total of 43 cases of Q fever were notified in the village of Noćaj, Srem county, Autonomous Province of Vojvodina, Republic of Serbia. Q fever was laboratory confirmed in 37 notified cases. Alhough, the outbreak is considered over, the outbreak investigation is still ongoing in order to identify aetiologic factors relevant for this outbreak.

Investigation of an outbreak of mycobacteriosis in pigs

Background

A high proportion of pigs imported to Serbia from a Lithuanian breeding herd reacted positively against avian and/or bovine tuberculin. The pigs were euthanized and lesions characteristic for mycobacterial infection were detected. An investigation of potential mycobacteriosis in the pigs imported to Serbia and the possible source of infection in the Lithuanian herd were therefore initialised.

Results

Formalin fixed, paraffin embedded lymph nodes from tuberculin positive animals were examined by real-time PCR for IS1245 and IS6110. IS1245 was detected in 55% and IS6110 in 11% of the samples. Seven of the ten IS6110 positive samples were positive for IS1245. Eleven lymph nodes from 10 pigs and 15 environmental samples were collected from the Lithuanian breeding herd and cultured for mycobacteria. M. avium subsp. hominissuis was detected in all lymph nodes and from eight samples of peat and sawdust. Isolates with identical and related IS1245- and IS1311 RFLP profiles were detected from swine and peat.

Conclusions

This study demonstrated cross reactions between avian and bovine tuberculin in pigs. Real-time PCR indicated infection with M. avium in the Serbian pigs. However, as a small proportion of the lymph nodes were positive for IS6110, infection with bacteria in the M. tuberculosis complex could not be ruled out. Analyses confirmed the presence of M. avium subsp. hominissuis in porcine and environmental samples from the Lithuanian breeding herd. The results indicate peat as a source of M. avium subsp. hominissuis infection in these pigs, and that the pigs imported to Serbia were infected with M. avium subsp. hominissuis.