Acta Microbiologica Bulgarica

41-45

Authors: Masalski, N., Najdenski, H.

Pest des petits ruminants (PPR) is a disease first described in 1941 in West Africa. It is caused by a virus belonging to the family Paramyxoviridae. The virus is highly virulent for goats and sheep. There is no virus carriage. The incubation period is 5-6 days. Mortality is high. Transmission of infection is through close contact between sick and healthy animals – infection occurs mainly through the respiratory tract. In pathogenesis, the lymphatic system plays a major role. The infection predominantly affects small ruminant flocks. Clinical symptoms are mainly lesions on the muzzle, nose and urogenital tract. Diagnosis is based on characteristic clinical and pathological anatomical evidence. Stringent measures are necessary to isolate and quarantine risky flocks and farms. In connection with a PPR epizootic in Syria, the import of lambs from our country was terminated. The team of Bulgarian specialists sent to Syria proved that Bulgaria had nothing to do with the epizootic in that country. In 2018, the dangerous disease of sheep and goats was detected in Bulgaria. Data reported in the press and other media seriously differed from the well-known characteristics of the Pest des petits ruminants infection.

53-59

Authors: R. Peshev, I. Sirakov

Bovine herpesvirus 4 (BoHV 4) is a member of the Herpesviridae family in the Gammaherpesvirinae subfamily, Radinovirus genus. The purpose of this study was to isolate BoHV 4 from calves, heifers and cows presenting various clinical entities – respiratory, conjunctivitis, pneumonia, skin damage, genital lesions and abortion, and to characterize its molecular biological features. Primary and permanent bovine cell cultures were used for virus isolation and culturing. Polymerase chain reaction (PCR) was used to confirm the gB and TK genes and the PCR products were sequenced. After infecting the primary bovine and permanent cell lines, a cytopathic effect typical of BoHV 4 was observed and 10 cytopathic viral agents were isolated. Amplification products with molecular weights of 567 and 615 bp for the Tk and gB genes, respectively, were found after PCR. After the BoHV 4 isolates had been sequenced, 473 and 476 nucleotide sequences were analyzed for the Tk and gB genes, respectively. The phylogenetic trees constructed based on the Tk and gB genes of Bulgarian BoHV 4 strains fall within the same branch with the reference BoHV 4 European strains deposited in the genomic bank and their genomic features were similar to European sequenced genomes of other Radinoviruses.

66-70

Authors: Dikova, B., Djourmanski, A.

Symptoms of virus diseases on the leaves of the medicinal plant species Echinacea purpurea (L.) Moench. – purple coneflower were observed in the trial fields of the Institute of Rose, Essential and Medicinal Cultures (IREMC) near Kazanlak and private gardens in Kazanlak, Bulgaria. Virus diseases, caused by the following viruses were established on E. purpurea: Alfalfa mosaic virus (AMV), Cucumber mosaic virus (CMV), Tobacco mosaic virus (TMV), Tomato spotted wilt virus (TSWV) and Potato virus Y (PVY). These viral pathogens existed in Echinacea plants in individual or most commonly in mixed infections. The symptoms caused by viral pathogens were spotting (chlorotic spots of different shape and size) on the leaves, sometimes typical mosaic, reduction in leaf size and flower head diameter and especially decrease in the height of the stems, called dwarfing. The results of the study have shown, that the most widely spread were СМV, АМV, ТМV - over 45 % and TSWV – nearly 30 %. Clear differences were detected in the yields of roots, seeds and leaves between Group I of symptomless Echinacea plants (practically healthy without symptoms or damage) and the spotted Echinacea plants (Group II – of spotted and dead plants and Group III - of spotted, but vital plants, in which the viruses were established. The spotted Echinacea plants were shorter (dwarfed) in comparison with the symptomless plants with fewer leaves and flower heads. The yield of the seeds, leaves and roots of the spotted plants was twice or several times lower in comparison with the symptomless plants.