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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Infectious Bacterial Diseases Research » Research » Publications at this Location » Publication #191519
Title: SEQUENCE CONSERVATION OF THE LEPTOSPIRAL IMMUNOGLOBULIN-LIKE (LIG) GENES AMONG PATHOGENIC LEPTOSPIRA SPP.

Author
item MCBRIDE, ALAN - OSWALDO CRUZ FOUNDATION
item CERQUEIRA, GUSTAVO - FEDERAL UNIV. OF PELOTAS
item MEDEIROS, MARCO - OSWALDO CRUZ FOUNDATION
item Zuerner, Richard
item REIS, MITERMAYER - OSWALDO CRUZ FOUNDATION
item HAAKE, DAVID - VA/UCLA
item KO, ALBERT - WEILL MED. COLL. CORNELL
item DELLAGOSTIN, ODIR - FEDERAL UNIV. OF PELOTAS

Submitted to: Gordon Research Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 2/10/2006
Publication Date: 4/22/2006
Citation: Mcbride, A.J., Cerqueira, G., Medeiros, M., Zuerner, R.L., Reis, M.G., Haake, D., Ko, A.I., Dellagostin, O.A. 2006. Sequence conservation of the Leptospiral immunoglobulin-like (lig) genes among pathogenic Leptospira spp. [abstract]. Gordon Research Conference Proceedings. Paper No. M1.

Interpretive Summary:

Technical Abstract: lig genes encode proteins that belong to the bacterial immunoglobulin-like (Big) superfamily of proteins, several of which are virulence determinants. Immunization with Lig proteins confers significant protection (70-100%) against lethal challenge in the hamster model. Since lig genes (ligA, ligB and ligC) appear to be present in all pathogenic Leptospira spp, Lig proteins may potentially serve as a vaccine candidate that confer cross-protective immunity against infections with heterologous serovars. To determine the level of sequence identify among lig genes, genomic DNA was extracted from representative pathogenic strains belonging to L. interrogans serovars Canicola and Pomona, L. weilii serogroup Hebdomadis, L. borgpetersenii serovar Hardjo and L. noguchii. The presence of the lig genes was determined by PCR screening with degenerate primers that were designed from available lig sequences for L. interrogans serovars Pomona, Copenhageni, Lai and Manilae, and L. kirschneri serovar Grippotyphosa. PCR products were sequenced using primer sets that generated overlapping fragments on both DNA strands such that each base was read a minimum of four times. Sequences were assembled into contigs using Vector NTI Suite 8. Only ligB was present in all of the pathogenic strains examined, although ligB from L. interrogans serovar Manilae contains a stop codon at position 3574 bp in the C-terminal non-Big-repeat domain region. The amino acid sequence of LigB has 61-100% sequence identify amongst different species. Furthermore, mosaicism was observed in ligB sequence suggesting that there may have occurred intra-species recombination at this loci. However, amino acid sequence identity was 93-97% among LigB from L. interrogans and L. kirschneri serovars. ligA was identified in L. interrogans serovars Copenhageni, Pomona, Manilae and Canicola and kirschneri serovar Grippotyphosa but not in L. interrogans serovar Lai and strains from L. noguchii, L. weilii and L. borgpetersenii. When present, ligA forms an operon-like region with ligB where the intergenic region between the two genes is ~950-1350 bp. In L. interrogans Lai and L. borgpetersenii Hardjo, ligA has been replaced by a transposonase and an IS element, respectively. The LigA sequence is highly conserved (81-97% identity) among serovars which express this protein. ligC is the most conserved lig gene (89-100% identity) and is present in all the pathogenic strains except L. noguchii. However, ligC appears to be a pseudogene in L. interrogans Copenhageni and L. kirschneri Grippotyphosa due to a stop codon and frameshift mutation. The sequence variation reported suggests that the sequence diversity observed among lig genes may play a role in the adaptation of serovars to specific host reservoirs. However, the amino acid sequence of Lig proteins is highly conserved among pathogenic serovars of public health importance, therefore indicating that a Lig-based subunit vaccine candidate may potentially induce cross-protective immune responses.