Porcine circovirus type 2 (PCV2) is the main causative agent of postweaning multisystemic wasting syndrome (PMWS). To characterize and determine the genetic diversity of PCV2 in the porcine population of Serbia, nucleotide and deduced amino acid sequences of the open reading frame 2 (ORF2) of PCV2 collected from the tissues of pigs that either had died as a result of PMWS or did not exhibit disease symptoms were analyzed. Sequencing and phylogenetic analysis showed considerable diversity among PCV2 ORF2 sequences and the existence of two main PCV2 genotypes, PCV2b and PCV2a, with at least three clusters, 1A/B, 1C and 2D. In order to provide further proof that the 1C strain is circulating in the porcine population, the whole viral genome of one PCV2 isolate was sequenced. Genotyping and phylogenetic analysis using the entire viral genome sequences confirmed that there was a PMWS-associated 1C strain emerging in Serbia. Our analysis also showed that PCV2b is dominant in the porcine population, and that it is exclusively associated with PMWS occurrences in the country. These data constitute a useful basis for further epidemiological studies regarding the heterogeneity of PCV2 strains on the European continent.

Mycoplasma hyopneumoniae is a primary agent associated with mycoplasma pneumonia and the porcine respiratory disease complex (PRDC). Various reports have indicated that different strains of M. hyopneumoniae are circulating in the swine population. Lysates from lung swabs from naturally infected pigs of different ages were tested according to a new variable number of tandem repeats (VNTR) genetic typing method based on the polyserine repeat motif of the P146 lipoproteoadhesin, which can be applied directly on clinical material without isolation of M. hyopneumoniae. The aim was to determine the diversity of M. hyopneumoniae isolates from conventional farrow-to-finish pig farms located in different geographical areas of Serbia. PCR amplification was carried out using M. hyopneumoniae -specific designed, conserved primers (p146MH-L and p146MH-R) flanking the region encoding the repeat motif, followed by sequencing and cluster analysis. Five groups of M. hyopneumoniae with thirteen to twenty-four serine repeats were observed. Analysis of three samples from each farm indicated that the specific isolate is ubiquitous in pigs of different ages. Furthermore, seven clusters were observed within 27 tested samples. The results indicated a considerable diversity among M. hyopneumoniae field isolates in the swine population from conventional farrow-to-finish farms in Serbia and suggest close genetic relatedness of the corresponding isolates.

Control of swine dysentery with antibiotics is often ineffective due to the resistance of Brachyspira hyodysenteriae. The potential of some herbal-based components against B. hyodysenteriae was previously studied in vitro. This study aims at the evaluation of in vivo effi cacy of phytogenic feed additives in the control of swine dysenteryThe study involved 64 seven-week old weaned pigs allotted to 4 groups: two were fed on feed supplemented with either Patente Herba® or Patente Herba® Plus, the third received tiamulin (positive control), while the negative control was not given antibiotics or additives. Fecal consistency was recorded daily. The presence of B. hyodysenteriae in the feces was investigated weekly using microbiological assays and the PCR test. Weight gain and feed conversion ratio were calculated for each week, and for the whole experiment.B. hyodysenteriae was detected in all samples by both methods. The additives showed effi cacy in the prevention and control of swine dysentery as only normal and soft stool was observed in the treated groups. By contrast, in the negative control all feces categories were detected. Frequencies of feces categories signifi cantly differed (p<0.001) between feed-supplemented groups and the negative control. Effi cacy of both additives in the prevention of SD is comparable to tiamulin, based on insignifi cant differences in the frequency of the various feces categories.Benefi cial effects of both additives resulted in signifi cantly (p≤0.05) higher weight gain and lower feed conversion ratio in comparison to the negative control. The average weight gains between additive-fed groups and tiamulin-treated group did not differ signifi cantly.

A retrospective study on 235 natural cases of Porcine Respiratory Disease Complex in order to determine the etiological agents, their prevalence and interrelationships was performed in Serbia. Lung tissue samples were analyzed by Polymerase Chain Reaction for the presence of Porcine circovirus type 2, Porcine reproductive and respiratory virus, Swine infl uenza virus, Mycoplasma hyopneumoniae, Pasteurella multocida, Actinobacillus pleuropneumoniae, Haemophilus parasuis, Streptococcus suis and Arcanobacterium pyogenes. A total of 49 different combinations of viral and bacterial pathogens were found. Five different viral and viral/Mhp co-infections were detected. Monobacterial infections were found in 150 cases and polybacterial infection was detected in 85 samples. PCV2 was the main virus detected, and Pm was the most aggressive secondary pathogen detected in PRDC. The reason for PRDC being so prevalent among Serbian pigs is most likely due to the large number of risk factors in the conventional farrow-to-fi nish system, compared to multisite production systems. Therefore, measures aimed at a better control of respiratory viruses, particularly Porcine circovirus type 2 and Porcine reproductive and respiratory virus, as well as Mycoplasma hyopneumoniae infections, and adoption of rational decisions on respiratory bacterial pathogens specifi c therapeutic and preventive strategies at herd level, simultaneously with signifi cant improvements on farm management should reduce the occurrence of PRDC.