Correlation between plasmid content and infectivity in Borrelia burgdorferi

Abstract

Infectivity-associated plasmids were identified in Borrelia burgdorferi B31 by using PCR to detect each of the plasmids in a panel of 19 clonal isolates. The clones exhibited high-, low-, and intermediate-infectivity phenotypes based on their frequency of isolation from needle-inoculated C3H͞HeN mice. Presence or absence of 21 of the 22 plasmids was determined in each of the clones by using PCR primers specific for regions unique to each plasmid, as identified in the recently available genome sequence. Southern blot hybridization results were used to confirm the PCR results in some cases. Plasmid lp25 exhibited a direct correlation with infectivity in that it was consistently present in all clones of high or intermediate infectivity and was absent in all low-infectivity clones. lp28 -1, containing the vmp-like sequence locus, also correlated with infectivity; all clones that lacked lp28 -1 but contained lp25 had an intermediate infectivity phenotype, in which infection was primarily restricted to the joints. Plasmids cp9, cp32-3, lp21, lp28 -2, lp28 -4, and lp56 apparently are not required for infection in this model, because clones lacking these plasmids exhibited a high-infectivity phenotype. Plasmids cp26, cp32-1, cp32-2 and͞or cp32-7, cp32-4, cp32-6, cp32-8, cp32-9, lp17, lp28 -3, lp36, lp38, and lp54 were consistently present in all clones examined. On the basis of these results, lp25 and lp28 -1 appear to encode virulence factors important in the pathogenesis of B. burgdorferi B31.

Overexpression of CsrA (BB0184) Alters the Morphology and Antigen Profiles ofBorrelia burgdorferi

“…A clonal, noninfectious isolate of B. burgdorferi strain B31 (ML23 , Table 1), lacking linear plasmid 25 (lp25 negative), was used for the overexpression of CsrA Bb (44,45,65). All B. burgdorferi cultures used for transformations were grown in 1% CO 2 at 32°C in Barbour-StoennerKelly II (BSK-II) liquid medium (pH 7.6) supplemented with 6% normal rabbit serum (Pel-Freez Biologicals, Rogers, AR) (51,52).…”

Dogs Vaccinated with Common Lyme Disease Vaccines Do Not Respond to IR6, the Conserved Immunodominant Region of the VlsE Surface Protein ofBorrelia burgdorferi

“…The failure of the bacterin-type vaccines to elicit anti-C 6 antibody is probably due to the loss of the lp 28-1 plasmid, which contains the vlsE gene, by the spirochete stocks used to generate such vaccines. As few as five culture passages are sufficient to generate B. burgdorferi clones that lack the lp 28-1 plasmid (17), and it is likely that the spirochetal isolates used to produce bacterin vaccines have undergone many more such passages and have therefore lost the ability to express VlsE. The C 6 peptide technology offers a more reliable single-test alternative to the standard two-tier method (18) of Lyme disease diagnosis in dogs.…”

Biology of Infection with Borrelia burgdorferi

“…Efforts to identify B. burgdorferi products that play roles in mammalian infection began by serially passaging strains in culture and correlating loss of infectivity with loss of specific plasmids [55,[104][105][106][107][108]. As genetic techniques have become available for B. burgdorferi analysis, other approaches have been applied to identifying genes that contribute to mammalian infectivity and the roles of some such genes have been rigorously defined by inactivation and restoration (complementation).…”