[Application of purified recombinant outer membrane lipoprotein LipL32 in detecting antibodies among leptospirosis cases].
OBJECTIVE
To establish recombinant outer membrane lipoprotein LipL32-based antibody detection assays in identifying leptospirosis.


METHODS
Recombinant leptospiral outer membrane protein LipL32 was obtained by genetic engineering method. This purified protein was used in the indirect and sandwich ELISA assays to test the antibodies in sera of human beings and rats, and the results were compared with those obtained by microscopy agglutination test (MAT) and imported ELISA kit.


RESULTS
When the acute and convalescent phase specimens from 9 leptospiral patients were tested, the detected rates of three ELISAs were similar to the MAT. Among the 45 probable cases which MAT showed positive, 32 (71.11%) samples were positive by r32-I-ELISA, 36 (80.00%) by r32-S-ELISA, while 28.89% (13/45) samples were positive and 55.56% (25/45) were suspicious by D.A.I-ELISA. The specificity of r32-I-ELISA and r32-S-ELISA were 97.10% (67/69) for 69 specimens. 43 healthy specimens were negative by both r32-I-ELISA and r32-S-ELISA, 14 healthy specimens were negative by D.A.I-ELISA. Among 16 non-leptospirosis patients, two specimens were positive by r32-I-ELISA and r32-S-ELISA, D.A.I-ELISA and identified one positive specimen, while 12 specimens were suspicious by D.A.I-ELISA. For 10 syphilis specimens, data obtained through three ELISAs were in consistent with that by MAT. A sandwiched ELISA, using rLipL32 protein as the antigen was developed to detect rat sera. Considering MAT as standard test, the sensitivity and specificity were 86.75% (131/151), 99.19% (122/123) respectively with coincidence rate as 92.34% (253/274).


CONCLUSIONS
The recombinant protein LipL32 had high immunoreactivity and could be used as an antigen for the detection of pathogenic leptospirosis. In summary, the novel sandwiched ELISA with rLipL32 showed similar sensitivity and specificity to that of MAT in the antibody detection of rat leptospirosis. It was suitable for large scales field sero-epidemiological studies.
Xu
Guo-ying
GY
Fujian Provincial Center for Disease Control and Prevention, Fuzhou 350001, China.
Yan
Yan-sheng
YS
Zhang
Zhi-shan
ZS
Li
Shi-qing
SQ
Wang
Ling-lan
LL
Deng
Yan-qin
YQ
Pan
Min-nan
MN
D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood*; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D006801:Humans; D007922:Leptospirosis / Q000097:blood / Q000175:diagnosis*; D008074:Lipoproteins / Q000276:immunology*; D051381:Rats; D011994:Recombinant Proteins / Q000276:immunology; D012680:Sensitivity and Specificity
D000907:Antibodies, Bacterial; D001425:Bacterial Outer Membrane Proteins; C406589:LipL32 protein, Leptospira; D008074:Lipoproteins; D011994:Recombinant Proteins