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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.

Canine leptospirosis is a zoonosis caused by bacteria belonging to the genus Leptospira. Dogs are one of the animal species involved in the cycle of preservation and transmission of leptospirosis in urban areas. Serological testing for the presence of specific antibodies against Leptospira spp. in dogs was continuously performed between 2010 and 2020 in the city of Belgrade. At the request of the owners themselves, other veterinary laboratories or laboratory clinics, 179 blood sera from 179 dogs were examined in the Laboratory for Immunology, Scientific Institute of Veterinary Medicine of Serbia. Blood sera samples from dogs were examined using the standard microscopic agglutination test (MAT) for the presence of specific antibodies against seven different serovars of Leptospira: Pomona, Icterohaemorrhagiae, Grippotyphosa, Sejroe, Canicola, Bataviae, and Australis. The number of seropositive dogs was 17/179 (9.5%). Among all examined sera, the highest titre of seropositive samples was to serovar Icterohaemorrhagiae (10/17, 58.8%), followed by Pomona (4/17, 23.5%), and serovar Canicola (3/17, 17.6%). Specific antibodies for serovars Grippotyphosa, Sejroe, Bataviae and Australis were not detected in any of the dog sera. Cross-reaction (the presence of two or three titres with different values where one of them was higher than others) between different serovars was diagnosed in a low number of sera (n=4), with the following serovars: Icterohaemorrhagiae and Pomona (n=3) and Pomona and Canicola (n=1). The confirmed specific antibody titres for Leptospira spp. were between 1:100 to 1:3000 (5 sera had titres of 1:100, 7 had titres of 1:300, 4 had titres of 1:1000, and 1 serum had a titre 1:3000). Monitoring canine leptospirosis is a useful tool in preventing leptospirosis in Belgrade.

Mycoplasma bovis infection in grazing dairy cows has not been reported in the Republic of Serbia to date. It is important to monitor its seroprevalence on the field. The presence of specific antibodies against M. bovis in the blood serum of grazing dairy cows is investigated in the present study. A total of 131 blood serum samples of clinically healthy dairy cows were examined. Sampling was performed during 2013 from five different areas in Serbia: Zasavica, Pozarevac, Gruza, Novi Sad and Banatski Karlovac. A commercial ELISA kit for diagnosis of M. bovis antibodies in blood serum samples, manufactured by Bio-X Diagnostics, Belgium, was used. Specific antibodies against M. bovis were identified in 13 out of 131 samples (9.92%) from 4 locations; the only negative location was the most southern Gruza. The revealed seroprevalence is evidence for the presence of M. bovis in grazing dairy cows in different locations of Serbia. Figure 1: Location of the 5 different areas of Serbia where grazing cows were sampled for Mycoplasma bovis serology: 1 -Zasavica, 2 -Pozarevac, 3 -Gruza, 4 -Novi Sad and 5 -Banatski Karlovac (MapCustomizer, https://www.mapcustomizer.com/). CONCLUSIONSSpecific antibodies against M. bovis were identified in 9.92% of the grazing cows from 4 areas; the only negative was the most southern region, Gruza. The revealed seroprevalence is the first evidence for the presence of M. bovis in grazing dairy cows in different locations of Serbia.

In this study we investigated the role of the Harderian gland in the immune response following vaccination against infectious bronchitis (IB). The experiment was carried out on 100 broiler chicks which were divided into two experimental groups. Experimental group O was vaccinated on the first day of age against infectious bronchitis with vaccine Bronhivet I batches that contain a live attenuated strain H120 and the control group did not get immunized. The experiment lasted 21 days. Blood sera were examined on days 1, 7, 14 and 21 for the presence of specific antibodies against infectious bronchitis (ELISA test). Histological changes were observed in the structure of the Harderian gland in relation to the applied vaccine. This research demonstrated the role of the Harderian gland as a secondary lymphoid organ in broiler vaccination against infectious bronchitis. Maternal antibodies present in the IB had no negative impact on the vaccination of chickens on the first day of age. The vaccine virus partially damaged the Harderian gland