Plasmids in Mycoplasma species isolated from goats and sheep and their preliminary typing

One-hundred-five (105) clinical isolates of mycoplasma from caprine origin and one isolate from ovine were surveyed for plasmids, which were present in thirty-three (31%) of them. These mycoplasmas originated from 13 herds. Ten of them were symptomatic for mycoplasmal disease (mastitis, polyarthritis, septicemia) and three herds were asymptomatic, i.e., clinically normal. Twenty-eight isolates were Mycoplasma mycoides subspecies mycoides LC (large colony or caprine biotype), four were Mycoplasma capricolum subsp. capricolum and one was Mycoplasma cottewii. The isolated plasmids were linearized by EcoRI, EcoRV, EcoRI and EcoRV or BamHI and EcoRV, and were of five sizes (1.1, 1.6, 1.7, 1.8, and 1.9 Kbp). Based on restriction enzyme digestion and size of the linearized supercoiled extrachromosomal DNA, five plasmid types were recovered (p1II, p2III, p2V, p3I, and p4IV). The small size of these DNA elements probably exclude replicative forms of DNA virus, which are equal or larger than 8.0 Kbp. Um total de 105 amostras clínicas de micoplasma, originárias de caprinos, e uma de ovino foram investigadas quanto a presença de plasmídios, que foram observados em trinta e três (31%) delas. Esses micoplasmas provieram de 13 rebanhos. Dez desses rebanhos eram sintomáticos para micoplasmose (mastite, poliartrite, septicemia) e três eram assintomáticos, i.é., clinicamente sadios. Vinte e oito amostras eram Mycoplasma mycoides subespécie mycoides LC ("large colony" ou biotipo caprino), quatro eram M. capricolum subsp. capricolum e uma era M. cottewii. Os plasmídios foram linearizados com endonucleases EcoRI, EcoRV, EcoRI e EcoRV ou BamHI e EcoRV e apresentaram cinco tamanhos (1,1; 1,6; 1,7; 1,8 e 1,9 Kbp). Com base na digestão pela enzima de restrição e o tamanho dos DNA extracromossomais, cinco tipos de plasmídio foram encontrados (p1II, p2III, p2V, p3I e p4IV). O reduzido tamanho desses DNA circulares muito provavelmente exclui formas replicativas de vírus DNA, cujo tamanho é igual ou maior que 8,0 Kbp.