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Infect Immun, June 1998, p. 2540-2546, Vol. 66, No. 6
Department of Parasitology, Tulane Regional
Primate Research Center, Tulane University Medical Center, Covington,
Louisiana 70433,1 and
Aquila
Biopharmaceuticals, Inc., Worcester, Massachusetts
016052
Received 26 September 1997/Returned for modification 30 December
1997/Accepted 24 March 1998
As an initial attempt to investigate the possible role of outer
surface protein A (OspA) escape mutants of Borrelia
burgdorferi in decreasing the efficacy of the OspA vaccine,
mutants of the HB19 strain of B. burgdorferi sensu stricto
were selected in vitro from an uncloned, low-passage-number isolate.
The antiserum used for selection was obtained from rhesus monkeys that
had been given a vaccine of the same formulation and dose, and by the
same route of administration, as that given to humans in several
trials. All of the mutants selected in liquid medium and subsequently cloned twice in solid medium expressed a single abundant protein of 28 to 34 kDa instead of both OspA and OspB. Depending on the mutant, this
protein reacted strongly, weakly, or not detectably with the anti-OspA
antibody used for selection. Analysis of the ospAB locus of
each of four representatives from these three groups of mutants by PCR
with oligonucleotide primers that hybridize to flanking regions of the
ospAB operon, and of the corresponding phenotype with
monoclonal antibodies that bind to the amino or carboxyl terminus of
the OspA or OspB polypeptide, indicated that in all cases a deletion
within the operon had occurred. Spirochetes from the four mutant
strains chosen for further analysis could be killed in
antibody-dependent, complement-mediated killing assays with the
selecting anti-OspA antibody, despite their resistance to killing with
this antibody in the absence of complement. Complement-mediated killing
occurred at an antibody concentration higher than that required to kill
wild-type spirochetes. If anti-OspA antibody acts only within the tick,
where complement is probably ineffective due to tick-derived
decomplementing factors, then OspA escape mutants, if infectious, could
seriously diminish the efficacy of OspA vaccines. On the other hand, if
the killing of B. burgdorferi with anti-OspA antibody also
takes place within the human host, then our results indicate that
chimeric/deletion escape mutants will be killed as well.
0019-9567/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Borrelia burgdorferi Escape Mutants That
Survive in the Presence of Antiserum to the OspA Vaccine Are Killed
When Complement Is Also Present


*
Corresponding author. Mailing address: TRPRC, 18703 Three Rivers Rd., Covington, LA 70433. Phone: (504) 892-2040, ext. 221. Fax: (504) 893-1352. E-mail: philipp{at}tpc.tulane.edu.
Present address: Departamento de Biología Molecular,
Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid,
Spain.
Present address: CEMIC, Laboratorio de Microbiología,
Buenos Aires, Argentina.
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