RESUMO
We have studied the effect of immune rabbit sera on the localized (LA) and diffuse (DA) adherence to HeLa cells of 10 enteropathogenic Escherichia coli (EPEC) strains belonging to serogroups O55, O86, O111, O119, and O142. Anti-La1 serum, obtained by rabbit immunization with an E. coli strain harboring a cloned DNA fragment from an EPEC LA plasmid, strongly inhibited the adherence of all serogroups but one (O142). Similar results were obtained with anti-LA2 serum, which is anti-O111 serum absorbed with a non-adherent O111:H- EPEC strain. In contrast, non-absorbed anti-O55 and anti-O111 sera showed an inhibitory effect mainly on the adherence of homologous strains. Except for one experiment diffuse adherence was not inhibited by any antiserum used. The inhibitory effect of immune sera on localized adherence does not seem to be correlated with plasmid curing since adherence plasmid pMS49 proved to be stable after treatment with anti-O55 and anti-O111 sera. The cross-inhibition of adherence by anti-LA sera suggests that localized adherence-related adhesins of the O55, O86, O111, and O119 strains share similar antigens.
Assuntos
Aderência Bacteriana/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Soros Imunes/farmacologia , Animais , Depressão Química , Escherichia coli/classificação , Escherichia coli/patogenicidade , Feminino , Células HeLa , Humanos , Soros Imunes/isolamento & purificação , Coelhos , SorotipagemRESUMO
Plasmids coding for drug resistance and localized adherence (LA) to HeLa cells were found in two enteropathogenic Escherichia coli strains belonging to serotypes O55:H- and O55:H6. Strain 49-81 HSJ (O55:H-) carries two plasmids, one coding for both ampicillin resistance (Apr) and LA (pMS49). Strain 71-82 HSJ (O55:H6) harbors only one plasmid, coding for resistance to sulfadiazine, chloramphenicol, kanamycin, ampicillin, and LA (pMS71). Plasmids pMS49 and pMS71 were transferred to E. coli K-12 711 and from this strain to E. coli K-12 J53. Curing with acridine orange of an Apr LA+ transconjugant showed that both characteristics were lost simultaneously. The plasmids have a molecular weight of approximately 55 X 10(6) and are the first naturally recombinant plasmids coding for adherence and drug resistance described in enteropathogenic E. coli.
Assuntos
Escherichia coli/genética , Fatores R , Adesividade , Conjugação Genética , Escherichia coli/efeitos dos fármacos , Escherichia coli/patogenicidade , Células HeLa , HumanosRESUMO
We have studied the effect of immune rabbit sera on the localized (LA) and diffuse (DA) adherence to Hela cells of 10 enteropathogenic Escherichia coli (EPEC) strains belonging to serogroups 055, 086, 0111, 0119, and 0142. Anti-La1 serum, obtained by rabbit immunization with an E. coli strain harboring a cloned DNA fragment from an EPEC LA plasmid, strongly inhibited the adherence of all serogroups but one (0142). Similar results were obtained with anti-LA2 serum, which is anti-0111 serum absorbed with a non-adherence 0111:H-EPEC strain. In contrast, non-absorbed anti-055 and anti-0111 sera showed an inhibitory effect mainly on the adherence of homologous strains. Except for one experiment diffuse adherence was not inhibited by any antiserum used. The inhibitory effect of immune sera on localized adhere3nce does not seem to be correlated with plasmid curing sinceadherence plasmid pMS49 proved to be stable a after treatment with anti-055 and anti-0111 sera. The cross-inhibition of adherence by anti-LA sera suggests that localized adherence-related adhesions of the 0.55, 0.86, 0111, and 0119 strains share similar antigens