RESUMO
Serotypes 3 and 8 of Actinobacillus pleuropneumoniae, the aetiological agent of porcine pleuropneumonia, have been reported to predominate in the UK. Direct serotyping of isolates of the organism is typically determined by the immunological reactivity of rabbit serum to its surface polysaccharides, but the method has limitations, for example, cross-reactions between serotypes 3, 6 and 8. This study describes the development of a serotype 3-specific pcr, based on the capsule locus, which can be used in a multiplex format with the organism's specific gene apxIV. The pcr test was evaluated on 266 strains of A pleuropneumoniae and 121 strains of other organisms, including all the major respiratory bacterial pathogens of pigs. The test was highly specific and sensitive and should be useful for differentiating strains of serotypes 3, 6 and 8, and in seroprevalence and epidemiological surveys in regions where serotype 3 is prevalent, such as the UK.
Assuntos
Actinobacillus pleuropneumoniae/classificação , Actinobacillus pleuropneumoniae/isolamento & purificação , Reação em Cadeia da Polimerase/métodos , Sorotipagem/veterinária , Infecções por Actinobacillus/microbiologia , Infecções por Actinobacillus/veterinária , Animais , Suínos , Doenças dos Suínos/microbiologiaRESUMO
We describe a highly sensitive and specific multiplex PCR, based on capsular loci and the species specific apxIV gene, that unequivocally differentiates serovar 3, 6, and 8 Actinobacillus pleuropneumoniae strains that are cross-reactive in conventional immunological tests.
Assuntos
Infecções por Actinobacillus/microbiologia , Actinobacillus pleuropneumoniae/classificação , Actinobacillus pleuropneumoniae/genética , Técnicas de Tipagem Bacteriana/métodos , Reação em Cadeia da Polimerase/métodos , Actinobacillus pleuropneumoniae/imunologia , Cápsulas Bacterianas/genética , Proteínas de Bactérias/genética , Reações Cruzadas/imunologia , DNA Bacteriano/química , DNA Bacteriano/genética , Humanos , Dados de Sequência Molecular , Sensibilidade e Especificidade , Análise de Sequência de DNARESUMO
The specificity between the sym-2 gene bred into certain cultivars of pea (Pisum sativum L.) and the nodX gene, present only rarely in isolates of Rhizobium leguminosarum, can be exploited to preempt competition or nodulation blocking by a Rhizobium strain indigenous to a soil environment. The principle is to isolate an R. leguminosarum strain prevalent in a locale, convert it into a strain that will nodulate a desirable pea cultivar carrying sym-2 by establishing nodX in it, and then use the resulting Rhizobium strain with the pea cultivar carrying sym-2. To accomplish this, we first constructed a transposon Tn5 derivative called Tn5nodX and an efficient delivery vehicle that is suicidal in R. leguminosarum. We tested the potential utility of the system in greenhouse experiments. The results are encouraging enough to warrant extensive experiments under field conditions.