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West Nile virus (WNV) is a zoonotic mosquito-borne virus classified as family Flaviviridae and genus Flavivirus. The first WNV outbreak in humans in the Republic of Serbia was recorded in 2012. Equids and dogs can show clinical symptoms after WNV infection and are often used as sentinels. This study aimed to (i) give insight into seropositivity for WNV in clinically healthy dog and horse sera in different regions of Serbia and (ii) compare diagnostic value of ‘in-house’ and commercially available indirect immunofluorescence (IFA) and enzyme-linked immunoassay (ELISA) tests to ‘gold standard’ virus neutralization test (VNT). Due to cross-reactivity, sera were tested for Usutu virus and tick-borne encephalitis virus in VNT based on the epidemiological data of field presence. Blood sera of dogs (n = 184) and horses (n = 232) were collected from 2011 to 2013. The seropositivity was confirmed by VNT in 36.9 % tested dog sera and 34.9% tested horse sera with highest positivity in regions near two big rivers, while in four dog and seven horse sera, positivity resulted from Usutu virus infection. Comparative results of diagnostic tests in dogs ranged from 18.7 % seropositivity by ‘in-house’ ELISA to 31.9% by commercially available ELISA. In horses, seropositivity ranged from 36.2% by ‘in-house’ IFA to 32.5% by commercially available IFA and from 26.3% by ‘in-house’ IgG ELISA to 20.9% by commercially available ELISA. There were no statistically significant differences according to the McNemar test between ‘in-house’ and commercially available IFA and ELISA test in horse sera, while the same was not true for two ELISAs used in dog sera (χ2 = 8.647, p = .003). Established seropositivity in dogs and horses was in accordance with the epidemiological situation and WNV spread in the Republic of Serbia and proven Usutu virus co-circulation. ‘In-house’ tests remain a valuable tool in early diagnostics of WNV.

Porcine Reproductive and Respiratory Syndrome is a viral disease of swine characterized by reproductive failure of breeding animals and respiratory disorders in all categories. The first PRRS case in Serbia was recorded in 2001 after illegal import of boar semen. PRRS is economically the most important disease due to significant direct and indirect losses. Today, for routine diagnosis of PRRS in infected herds serological methods (ELISA) and molecular methods are used. Although modern diagnostic techniques are very robust, exceptional diversity of the viral strains is often the obstacle for an accurate diagnosis. To estimate the performance of seven different methods for PRRSV genome detection, twenty samples were used. However, none of the methods was able to detect all PRRSV strains. The best sensitivity was obtained by combining two methods. Until today, there is no absolutely accurate test which enables the detection of all circulating strains.

Due to the modern way of life, the global exchange of goods, more frequent contacts, and the closer life with pets, domestic and exotic animal species, different species are also more often exposed to various coronaviruses (CoVs). Most CoVs are species-specific and are not transmitted between different species. Many CoVs have been found to spread very rapidly after introduction into the susceptible population and have remained endemic despite vaccination attempts and other measures to prevent their spread. The majority of animal CoV are present in susceptible population and can cause from mild to a severe clinical picture of the disease, including high mortality. Very rarely strains of animal CoVs are transmitted to humans and then spread rapidly among humans like severe acute respiratory syndrome CoV-2 (SARS CoV-2). The epizootiological characteristics of coronavirus infections are a consequence of their unique characteristics that can be classified into three basic epizootiological determinants. First of all, the virus itself has its own characteristics in terms of genetic characteristics and sustainability in the environment. In relation to the second epizootiological determinant, the macro-organism, it is necessary to emphasize that coronaviruses, more often than other families of viruses, adapt to primary species o even to a new species of animal in nature. This, so-called "jumping" the species barriers, is primarily conditioned by the biology of the virus, which often changes the antigenic composition and thus not only avoids the host's immune response but also finds new species in nature for its maintenance. For thousands of years, the environment greatly contributes to the fact that coronaviruses are a companion of populations of many animal species since there are certain characteristics of the environment (third epizootiological determinant) as sharing the same ecological niche by different species of animals (and humans).

The golden jackal (Canis aureus) is a medium-sized canid species native to Europe. This species is characterized by rapid large-scale expansion. A similar trend is also observed in Serbia, where the species is now distributed in more than a half of the territory. Although jackals prefer habitats in human-dominated landscapes, these animals have not been studied well enough from an eco-epidemiological point of view, and little is known about their potential for carrying zoonotic pathogens. In a study conducted during a three-year period (01/2010-02/2013), a total of 216 hunted or road-killed golden jackals were collected from 10 localities in Serbia. Ticks, when present, were removed, and after necropsy, spleen samples were collected from each animal. All tick and spleen samples were tested for the DNA of bacterial and protozoan tick-borne pathogens (Borrelia species, Bartonella species, Rickettsia species, Anaplasma species, Coxiella burnetii, Francisella species and Babesia species) by multiplex real-time PCR, conventional PCR and sequencing analyses. The DNA of Babesia canis was detected in nine out of 216 (4.2%) spleen samples, and two samples (0.9%) tested positive for Anaplasma phagocytophilum. In 118 ticks collected from jackals, the DNA of two Babesia species (Ba. canis and Ba. microti), three Borrelia species (Bo. garinii, Bo. valaisiana, and Bo. lusitaniae) and A. marginale was detected. From the aspect of public health surveillance, the potential role of the golden jackal in the maintenance of vector-borne zoonotic pathogens in Serbia must be considered, and further eco-epidemiological studies should be performed to determine the precise role of this animal species in zoonotic disease transmission cycles.

The presence of equine herpesviruses 1, 2 and 5 (EHV-1, EHV-2 and EHV-5) was examined in 66 samples of spinal cord, submandibular lymph nodes and spleen of healthy, non-vaccinated abattoir horses from different locations in the Republic of Serbia. Virus isolation was conducted on RK-13 cell line with the confirmation of isolated viral strains by multiplex nested polymerase chain reaction. The cytopathic effect was observed 48–72 h after the first inoculation in 28 (42.4%) organ samples, and after 5 days in 11 other samples (16.7%) that were all confirmed as EHV-1. Four other samples (6.1%) that showed cytopathic effects on day 5 of the third passage were all positive for EHV-5. Additionally, EHV-1, EHV-2, and EHV-5 were directly detected in all organs by multiplex nested PCR in 46 (69.7%), 3 (4.5%), and 7 (10.6%) samples, respectively. The molecular characterization based on nucleotide sequencing of the part of the gB gene showed that Serbian EHV-1 isolates were 100% homogenous and clustered with EHV-1 strains from Turkey, the United Kingdom, the United States, and Japan. The EHV-2 strain from Serbia branched together with Turkish EHV-2 isolates with homogeneity from 96% to 98%. Serbian EHV-5 strains can be separated in one distinct cluster with isolates from Turkey and the United States with homogeneity from 98 to 99%. These data represent the first report of the molecular characterization of EHV-1, EHV-2, and EHV-5 in the horse population of the Republic of Serbia and document the first successful isolation of Serbian EHV-5 strains.

The goal of this study was to compare the results of serological and conventional bacteriological methods with the results obtained using multiplex PCR Bruce-ladder assay. Based on the obtained results, the usability of the assay was assessed in regard to rapid diagnosis of canine brucellosis directly from the samples of reproductive organs of infected dogs. Out of 225 blood samples, 33 (14.67%) had a positive agglutination reaction. In this study, out of the 225 assayed reproductive organs of dogs, B. canis was isolated from 3 samples (1.33%), while the PCR Bruce-ladder assay detected two positive samples (0.88%). Two dogs from which B. canis was isolated, an antibody titer of 1/200 was established in blood serums, and third dog from which B. canis was isolated was negative using the tube agglutination test. From a total of 225 assayed organ samples, a positive PCR reaction was obtained from two samples. The obtained results show that the tube agglutination method remains the first choice for the detection of dogs infected with B. canis. In addition, whenever possible, it is necessary to try isolation. It is desirable to attempt the detection of B. canis in tissues using PCR, but the results may not be treated as definitive and reliable.

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.

The results on serological testing of blood sera from stallions and mares used for breeding and the presence of the viral genome of Equine Arteritis Virus (EAV) in stallion semen are presented. The blood and semen samples were taken from a horse stable on the territory of the Republic of Serbia during 2012, 2013 and 2014. Detection of anti-EAV specific antibodies in blood sera was performed by the virus neutralization test (VNT), and identification of EAV genome RNA in stallion semen was done by reverse-transcriptase polymerase chain reaction (RT-PCR). In 2012, high seroprevalence of EAV was detected in the investigated stable. In total, 45% and 65 % of stallions and mares reacted positive, respectively, and the antibody titre values ranged between 2 and 10 log2. High seroprevalence was confirmed in the same animals again in 2013. Out of two stallions tested semen samples in 2013, the viral genome was detected by RT-PCR in 3 examined semen samples from a seropositive stallion, while EAV was not detected in 3 semen samples of a seronegative stallion. During 2014, 11 semen samples were collected from two seropositive stallions. Again, the presence of EAV was confirmed by RT-PCR in all 8 semen samples originating from the same stallion with the EAV genome positive semen result in 2013, whereas the virus was not detected in semen samples originating from the second anti-EAV antibody positive stallion. The presence of EAV-specific antibodies was confirmed in the blood sera of the mares inseminated with the semen of seropositive stallions in 2012 and 2013.

Leptospirosis is a bacterial zoonosis with worldwide distribution. This disease is facilitated among stray dogs due to their lifestyle and the absence of immunoprophylaxis. The aim of the present study was to provide serological data on the presence of certain serovars of Leptospira spp., which are assumed to circulate in the population of stray dogs in Serbia. During a period of 3 years (from April 2010 to June 2013), 1045 canine sera originating from 11 shelters were submitted to the laboratory of the Department of Infectious Animal Diseases and Diseases of Bees, Faculty of Veterinary Medicine, Belgrade. A microscopic agglutination test (MAT) was performed to detect antibodies to Leptospira (cutoff, 1: 100). The overall seroprevalence was 5.45% (57/1045) and the most prevalent Leptospira serovars were Icterohaemorrhagiae 33.3% (19/57), Pomona 29.8% (17/57), Canicola 14.0% (8/57), Grippotyphosa 3.5% (2/57), Bataviae 1.7 % (1/57), and Sejroe 1.7% (1/57). All dogs were seronegative for antibodies against serovars Australis and Bratislava. The results showed that stray dogs contribute to the spread and maintenance of Leptospira spp. in Serbia. Due to close contact with humans it is very important to improve the prevention of leptospirosis in dogs and support a One Health approach.

Kada se bruceloza ustanovi u jednoj zemlji, međunarodni veterinarski propisi nameću ograničenja kretanja životinja i trgovine, što dovodi do velikih ekonomskih gubitaka. Izolacija Brucella spp. konvencionalnim bakteriološkim tehnikama je dugotrajna, rizična za laboratorijske radnike i niske osetljivosti zbog česte kontaminacije materijala. Negativna izolacija ne isključuje postojanje bruceloze. Najbolji rezultati do sada su dobijeni kombinovanjem metoda izolacije i PCR metode na kliničkim uzorcima. Nedostatak PCR metoda baziranih na razlici među sojevima unutar vrste stimulisao je razvoj novih tehnika „otisaka prstiju”. Podaci o sekvenci celog genoma brucela omogućili su identifikaciju i razlikovanje brucela na nivou vrste, biovara i upoređivanje sojeva što je olakšalo pronalaženje izvora infekcije. Indirektni dijagnostički testovi su zasnovani na detekciji imunskog odgovora izazvanog infekcijom. Ovi testovi pokazuju različit stepen osetljivosti i specifičnosti zavisno od brojnih varijabli, poput stepena i načina inficiranja, prisustva takozvanih „unakrsno reaktivnih bakterija” antigenski sličnih Brucella spp, kinetike indukovanog imunskog odgovora i prethodne vakcinacije. Imajući u vidu kinetiku nastajanja imunskog odgovora indukovanog nakon infekcije, vreme kada će se različiti testovi izvoditi ima veliki uticaj na rezultate. When brucellosis is detected in a country, international veterinary regulations impose restrictions on animal movements and trade, which result in huge economic losses. The isolation of Brucella spp. through conventional bacteriological techniques takes a long time, it’s risky for the laboratory workers, and has low sensitivity due to the frequent contamination of materials. Negative cultures do not rule out the disease. The best results have so far been obtained by combining culture and PCR detection on clinical samples. The lack of PCR-based methods for differentiation among strains within a species stimulate the development of new techniques-”fingerprinting methods”. Data on the sequence of the genome of Brucella enabled the identification and differentiation of Brucella at the level of species and biovar and comparison strains which is easier to find the source of infection. Indirect diagnostic tests are based on the detection of immune responses induced by infection. These tests show different sensitivities and specificities depending on numerous variables, such as the infection dose and route, the presence of so-called “cross-reactive bacteria” antigenically similar to Brucella spp., the kinetics of the induced immune response, and previous vaccination. Bearing in mind kinetics of the immune response induced after infection, the time when the different tests carried out has a major impact on the results.

Canine Monocytic Ehrlichiosis is a zoonotic bacterial disease with worldwide distribution. With regards to the population of stray dogs, the disease is facilitated due to their lifestyle and the lack of anti-parasitic protection. The aim of this study was to provide serological data on the presence of a specific Ehrlichia canis IgG antibodies in stray dogs, originating from 7 municipalities in Serbia. During the period from April 2013 to June 2014, 217 canine sera were submitted to the laboratory of the Department of Infectious Diseases of Animals and Bees, Faculty of Veterinary Medicine in Belgrade. An immunofluorescent antibody test (IFAT) was performed to detect antibodies to Ehrlichia canis (cut off, 1:50). Seropositive dogs were found in 5 out of 7 counties with a seroprevalence varying from 3.57% to 20% and an overall seroprevalence of 11.06% (24/217). There was no statistically significant difference between the prevalence of infection and the host age or gender. Results showed that stray dogs contribute to maintaining and spreading of Ehrlichia canis in Serbia. Due to the close relationship between people and dogs, it is of great importance to constantly monitor and improve prevention of this disease.

This study includes examination of dogs from the territory of Serbia during the period from 2004. To 2011. Most of the dogs were from the territory of Belgrade. The total of 193 blood serum samples of proprietary dogs and 120 blood serum samples of stray dogs were tested for the presence of antibodies against Brucella canis. For diagnostics there was used the method of slow serum agglutination in test tubes with 2- mercaptoethanol. During eight years' period of investigation, out of 193 tested serums taken from proprietary dogs, 29 serum samples, or 15.03%, had undoubtedly positive titre of 1/200. During 2011. Out of 120 tested blood samples taken from stray dogs from Belgrade territory, positive titre of 1/200 had 8 samples, or 6.67%. The results of this investigation point out to a very high seroprevalence of antibodies against B.canis in dogs population from the teritiry of the Republic of Serbia. Ovim radom obuhvaćeno je ispitivanje pasa sa teritorije Republike Srbije, u periodu od 2004. do 2011. godine. Većina testiranih pasa poticala je sa teritorije grada Beograda. Na prisustvo antitela protiv Brucella canis, ukupno su ispitana 193 uzorka krvnih seruma pasa poznatih vlasnika i 120 uzoraka krvnih seruma pasa lutalica. Za dijagnostiku je korišćena metoda spore serumske aglutinacije u epruveti, sa 2-merkaptoetanolom. U toku osmogodišnjeg ispitivanja pasa poznatih vlasnika, od 193 ispitana seruma, sigurno pozitivan titar 1/200 imalo je 29 uzoraka seruma ili 15,03%. U toku 2011. godine ispitano je 120 uzoraka krvnih seruma pasa lutalica sa teritorije Beograda, od kojih je sigurno pozitivan titar 1/200 imalo 8 uzoraka ili 6,67%. Rezultati ispitivanja ukazuju na vrlo visoku seroprevalenciju antitela protiv B. canis u populaciji pasa sa teritorije Republike Srbije.

Rabies is a disease that occurs both in animals and people, with relatively long period of incubation, intense clinical course and fatal ending. Majority of cases of illnes and death in people are caused by the standard rabies virus. According to books of regulations on suppression and eradiction of rabies from 1988. and 2009., each suspected rabies has to be laboratory confirmed. From 2006. to 2012. within the passive surveilance, 3549 samples of brain tissue were examined for the presence of rabies virus. The virus was confirmed in 923 samples by using the method of direct imunofluorescence. From 2006. to 2012. there were diagnosed 192, 160, 233, 181, 104, 43 and 10 positive cases, respectively. For the purpose of rabies eradiction at the territory of the Republic of Serbia, a regional project of oral vaccination of foxes against rabies has been implemented since 2010.Within monitoring of the effectiveness of oral vaccination against rabies which was carried out at the end of 2011. and at the beginning of 2012., there were examined 1385 samples, out of which 11 reacted positively. The virus was dominantly present in the fox population. During 2008. and 2009., a relatively large number of rabid cats was registered, what indicates a transmission of rabies from the fox to the cat population. The incidence of rabies at the territory of Serbia significantly differs from one epizootic area to another. Northern parts of the country (Sombor and Subotica epizootic regions) have more favorable situation with only two cases of rabies for the last 7 years. In the period until 2010., in Pozarevac, Novi Sad, Jagodina, Pancevo, Belgrade and Nis epizootic region, a gradual decline in number of positive cases was noticed. International project for oral vaccination of foxes against rabies which has been implemented at the territory of the Republic of Serbia and neighboring countries, influenced a significant reduction of registered rabies cases. Besnilo je bolest životinja i ljudi koja se odlikuje relativno dugim inkubacionim periodom i dramatičnim kliničkim tokom, koji se uvek završava smrtnim ishodom. Najveći broj slučajeva oboljenja i smrti ljudi potiče od infekcije klasičnim virusom besnila. Prema pravilnicima koji se bave suzbijanjem i iskorenjivanjem besnila iz 1988. i 2009. godine obavezna je laboratorijska potvrda svake klinički opravdane sumnje na besnilo. Od 2006. do 2012. godine u okviru pasivnog nadzora pregledano je 3549 uzoraka moždanog tkiva na prisustvo virusa besnila. Metodom direktne imunofluorescencije virus je dokazan u 923 uzoraka. Po godinama, od 2006. do 2012. godine dijagnostikovano je 192, 160, 233, 181, 104, 43 i 10 pozitivnih slučajeva. U cilju iskorenjivanja besnila na teritoriji Republike Srbije od 2010. godine se sprovodi regionalni projekat oralne vakcinacije lisica protiv besnila. U okviru monitoringa efikasnosti oralne vakcinacije lisica protiv besnila koji je sprovođen krajem 2011. i početkom 2012. godine ispitano je 1385 uzoraka od čega je 11 reagovalo pozitivno. Virus je dominantno prisutan u populaciji lisica. Tokom 2008. i 2009. godine dijagnostikavan je relativno veliki broj besnih mačaka, što ukazuje na prenos virusa iz populacije lisica u populaciju mačaka. Incidencija besnila na teritoriji Srbije se značajno razlikuje od jednog do drugog epizootiološkog područja. Severni delovi zemlje (somborsko i subotičko epizotiološko područje) imaju povoljniju epizootiološku situaciju (samo dva slučaja besnila u proteklih 7 godina). U periodu do 2010. godine na požarevačkom, novosadskom, jagodinskom, pančevačkom, beogradskom i niškom epizootiološkom području se uočava postepeni pad broja pozitivnih slučajeva. Međunarodni projekat oralne vakcinacije lisica protiv besnila koji se sprovodi na teritoriji Republike Srbije i okolnih zemalja uticao je na to da se broj prijavljenih slučajeva besnila u Srbiji drastično smanji.

Intrauterine infection of the fetus occurs if a pregnant non-vaccinated sow is infected with the virus of classical swine plague (CSF). The infection of the fetus results in the occurrence of viremia and the distribution of the virus in fetal tissue is similar to the distribution which is established in post-natal infected swine. The objective of these investigations was to determine intrauterine (transplacental) infection in the event of the appearance of CSF in different periods of pregnancy in non-vaccinated and vaccinated sows. The examined material were organs and tissue of fetuses within two examined cases of CSF in non-immune pregnant sows. In the third examined case of CSF, the material comprised the blood of piglets before suckling the colostrum, animals originating from vaccinated sows, at a farm in which CSF had been diagnosed. Samples of tissue and blood of the piglets were examined for the presence of antigens and specific antibodies against the CSF virus using the immunoenzyme technique (ELISA). Even though the investigations were performed on a small number of samples, the obtained results raise the question of the possibility of the occurrence of intrauterine infection with a CSF field virus in sows vaccinated with the C-strain of CSF. The syndrome of a carrier sow and persistent infections are the chief problem factors that need to be considered within the programme of curbing and eradicating classical swine plague. Ukoliko se suprasna nevakcinisana krmača inficira virusom klasične kuge svinja (KKS) dolazi do nastanka intrauterine infekcije fetusa. Posledica infekcije fetusa je pojava viremije. Distribucija virusa u njihovim tkivima je slična onoj koja se ustanovljava kod postnatalno inficiranih svinja. Cilj ispitivanja je bio ustanovljavanje intrauterine (transplacentarne) infekcije u slučaju pojave KKS u različitim periodima suprasnosti kod nevakcinisanih i vakcinisanih krmača. U okviru dva slučaja KKS kod neimunih suprasnih krmača materijal za ispitivanja je obuhvatao organe i tkiva fetusa. U trećem ispitivanom slučaju KKS, materijal je obuhvatao krv prasadi pre sisanja kolostruma, koja su bila poreklom od vakcinisanih krmača, na farmi gde je dijagnostikovana KKS. Uzorci tkiva i krvi prasadi su ispitivani na prisustvo antigena i specifičnih antitela protiv virusa KKS imunoenzimskom (ELISA) tehnikom. Iako su ispitivanja obavljena na malom broju uzoraka, dobijeni rezultati nameću pitanje mogućnosti nastanka intrauterine infekcije terenskim virusom KKS kod krmača vakcinisanih K-sojem virusa KKS. Sindrom krmače kliconoše i perzistentne infekcije su glavni otežavajući faktori koje je potrebno dodatno sagledavati u okviru programa suzbijanja i eradikacije KKS.

The pathomorphological changes established following infection with the virus of classical swine plague in non-immune individuals are well known. However, piglets present a problem from the clinical-pathological aspect, in which this virus can be multiplied in spite of established colostral antibodies, but without the exhibiting of the clinical symptoms characteristic for the disease. The question of the characteristics of the pathomorphological finding is raised in the event of the breakdown of the colostral immunity of the piglets. With the objective of determining the influence of colostral antibodies on the development of pathomorphological changes in classical swine plague, piglets aged 28, 35, 44, and 54 days, originating from sows that had received a vaccine of the K-strain of the classical swine plague virus, were experimentally infected with a virulent variety of this virus (Becker strain). The control group comprised non-vaccinated animals originating from non-vaccinated sows. Following the death and/or sacrificing of the piglets in the experiment, a pathomorphological examination was performed of all organic systems and the presence of classical swine plague virus antigens was established in organs and tissues of piglets using the immunoenzyme (ELISA) test. Even though clinical signs characteristic for this disease were not found in all animals following artificial infection, the pathomorphological findings following death and/or sacrificing indicated a successful experimental infection and was typical for the acute course of classical swine plague. Bleeding was established in most organs and serous membranes (haemorrhagic diathesis). However, certain variations were also established regarding the expression and distribution of the pathomorphological changes in certain animals. Patomorfološke promene koje se ustanovljavaju posle infekcije izazvane virusom klasične kuge svinja (KKS) kod neimunih jedinki su dobro poznate. Međutim, sa kliničko-patološkog aspekta problem predstavljaju prasad, kod kojih se i pored ustanovljenih kolostralnih antitela virus klasične kuge svinja može da umnožava, ali bez ispoljavanja kliničkih simptoma karakterističnih za KKS. Postavlja se pitanje karakteristika patomorfološkog nalaza u slučaju probijanja kolostralnog imuniteta prasadi. Radi ustanovljavanja uticaja kolostralnih antitela na razvoj patomorfoloških promena kod KKS, izvedena je eksperimentalna infekcija virulentnim virusom KKS (soj Beker) prasadi u uzrastu 28, 35, 44. i 54. dana koja potiču od krmača vakcinisanih K-sojem virusa KKS. Kontrolna grupa je obuhvatala nevakcinisane jedinke, koje potiču od nevakcinisanih krmača. Posle uginuća i/ili žrtvovanja prasadi u ogledu, obavljen je patomorfološki pregled svih organskih sistema i prisustvo antigena virusa KKS je utvrđivano u organima i tkivima prasadi imunoenzimskim (ELISA) testom. Iako nakon veštačke infekcije kod svih jedinki nisu ustanovljeni klinički znaci karakteristični za klasičnu kugu svinja, patomorfološki nalaz posle uginuća i/ili žrtvovanja je ukazao na uspešnu eksperimentalnu infekciju i bio je tipičan za akutni tok KKS. Ustanovljena su krvarenja u većini organa i seroznih membrana (he- moragična dijateza). Međutim, utvrđene su i izvesne varijacije u pogledu izraženosti i distribucije patomorfoloških promena kod pojednih jedinki.

The objective of these investigations was to check on laboratory white mice the protective effect of an inactivated bivalent vaccine prepared from serotypes 1/2a and 4b L. monocytogenes. Following verification of the sterility and toxicity of the prepared vaccine, the mice were divided into 6 groups with 10 animals in each group. The first and second group of mice were administered the vaccine without saponin (vaccine A) and the third and fourth group the vaccine with saponin (vaccine B). Mice of the fifth and the sixth group were not vaccinated and served as a negative control. Two weeks following vaccination, the experimental groups were revaccinated, with the exception of the two control groups. Two weeks following revaccination, all groups were artificially infected with serotypes 1/2a and 4b L. monocytogenes. During the course of the investigations (60 days) a total of 4 mice died in the vaccinated groups. Mice of the control groups started dying after day 7, and the last mouse in these groups died 14 days after the infection. Examinations of preparations of parenchymatous organs of the dead mice stained according to Gram proved the presence of L. monocytogenes. Homogenates of parenchymatous organs were sown on tryptose agar for reisolation and a pure culture of L. monocytogenes was obtained. Through the use of specific antiserums, serotypes 1/2a and 4b were confirmed. Considering the total number of vaccinated mice in the experiment and the percent deaths (10%), it can be said that the investigated vaccine with saponin had a satisfactory protective effect. [Projekat Ministarstva nauke Republike Srbije, br. TR-20142 i TR-31088]

An experimental study was conducted to investigate the course of classical swine fever (CSF) infection in piglets originating from sows vaccinated with China strain vaccine. The experiment was carried out on 24 piglets (age 28, 35, 44 and 54 days) from vaccinated sows and on 11 non vaccinated piglets, originated from non CSF vaccinated sows. Two piglets from the each age group originating from vaccinated sows were challenged by intramuscular injection with CSF virus. Four piglets of the same age from vaccinated sows, and two piglets derived from unvaccinated sows were added to the challenged group to determine contact (horizontal) infection. After challenge, clinical examination and blood sampling from every animal was carried out on day 0, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27 and 29. Blood samples were examined for CSF virus specific antibodies by ELISA test, and for viral antigen i. e. viral RNA by RT-PCR technique. After death or sacrifice pathomorphological changes, presence and distribution of CSF virus antigen were detected in piglet tissue samples by ELISA test. On the basis of the obtained results it can be concluded that not all piglets born to vaccinated sows have maternal antibodies at a detectable level, and the issue of the efficiency of passive immunization needs to be evaluated in the future. Ova istraživanja su izvršena u cilju praćenja toka oboljenja nakon infekcije prasadi virusom klasične kuge svinja (KKS) poreklom od krmača vakcinisanih Kina sojem virusa KKS. Ogled je obavljen na 24 praseta (uzrasta 28, 35, 44 i 54 dana) poreklom od vakcinisanih krmača i na 11 nevakcinisane prasadi poreklom od nevakcinisanih krmača. Po dva praseta iz svake starosne grupe, poreklom od vakcinisanih krmača, su veštački inficirana intramuskularnom aplikacijom virusa KKS. U cilju ustanovljavanja kontaktne (horizontalne) infekcije, direktno inficiranim jedinkama su dodata po četiri praseta istog uzrasta poreklom od vakcinisanih krmača i dva praseta poreklom od nevakcinisanih krmača. Nakon veštačke infekcije, vršen je klinički pregled i uzorkovanje krvi od svake životinje 0, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27 i 29 dana ogleda. Uzorci krvi su ispitivani ELISA testom na prisustvo specifičnih antitela protiv virusa KKS, na prisutvo antigena virusa KKS odnosno virusne RNA metodom RT-PCR. Nakon uginuća ili žrtvovanja, vršen je patomorfološki pregled i utvrđivanje prisustva i distribucije antigena virusa u uzorcima tkiva ELISA testom. Na osnovu postignutih rezultata istraživanja može se zaključiti da pojedina prasad, poreklom od vakcinisanih krmača, nemaju detektabilna specifična antitela što nameće razmatranje pitanja efikasnosti pasivne imunizacije.

Summary Foot-and-mouth disease virus (FMDV) was analysed using 30 monoclonal antibodies (MAbs) obtained from Balb/c mice immunized with FMDV C3 Resende (C3R) subtype 7 and 14 days before fusion No. 15 and 16 respectively. Fourteen MAbs were neutralizing and by means of competition radioimmuno assay it was possible to classify them into four groups. The first group consisted of MAbs specific for three sequentional and three conformational epitopes. The second group consisted of MAbs specific for two conformational and for one sequentional epitope. The third and the fourth groups consisted only of one MAb each, being specific for conformationally and one sequentionally dependent epitope, respectively.

Background Aujeszky’s disease is a viral disease of suids caused by Suid Herpesvirus 1. The disease has worldwide distribution with significant economic impact. In Serbia, there is neither an Aujeszky’s disease eradication nor national vaccination programme of domestic pigs. Since clinical symptoms of Aujeszky’s disease are not specific, it is important to establish a link between clinical signs and presence of ADV active infection in wild boars. The aim of this study was to investigate the possibility of active infection within wild boar showing signs of ADV and also to examine relationship between isolates from domestic pigs and wild boar. Having in mind that virus has not been previously isolated from wild boars in Serbia, we report the first isolation of Suid Herpesvirus 1 from this species in Serbia. Results Tissue and serum samples from 40 wild boars from eastern Serbia were examined for evidence of Aujeszky’s disease (AD). Suid Herpesvirus 1 (SHV1), the cause of AD was isolated on PK15 cell line from three tissue samples, inducing cytopathic effect (CPE) with syncytia forming, and viral genome was detected by polymerase chain reaction (PCR) in eight samples. Genetic analysis of us4, us9 and ul49.5 partial sequences showed high homology between ADV isolates from wild boars and between isolates from wild boars and domestic animals. Neutralizing antibodies were not detected by virus neutralisation test (VNT) in sera from four out of eight PCR positive wild boars suggesting recent infection in those animals. Conclusions This is the first demonstration of Aujeszky’s disease virus (ADV) in the wild boar population in Serbia although seroconversion has been detected previously.