| Leptospirosis, caused by infection of Leptospira interroans, is a widespread zoonosis in the world. This disease is one of the infectious diseases, which is especially monitored and controlled in flood and water logging. There are numerous serogroups of L. interroans and low or even no cross-protection among them. Epidemic dominant serogroups of the L. interroans were found to be distinct in different areas. Therefore, so far in home and aboard epidemic dominant serogroups of L. interroans in local are selected to prepare polyvalent vaccine. However, this kind of vaccine offers little protection effects to the infection by the other serogroups of the microbe that not involved in the vaccine. Recently, in many areas of our country north-toward migration of L. interroans serogroup Icterohaemorrhagiae and epidemic of L. interroans serogroup Sejroe serovars medanesis are present. In addition, side effects of currently generally used polyvalent vaccine made of whole dead leptospira are quite serous, which are not easily accepted by populations resulting in the difficulty of spread and application of the vaccine. Risk of leptospirosis epidemic on large scale in many areas appeared because of decreased levels of specific antibodies against dominant leptospira] serogroups in local populations. Thus, finding leptospiral genus-specific protective antigens shows important significance to further develop universal vaccinefor prevention and control of leptospirosis.It was well confirmed that saprophytic L. biflexa serogroup Semaranga serovar patoc strain Patoc I after inactivated at 80C and recovered with normal saline could be agglutinated by antibodies in sera from all the leptospirosis patients. This data indicate the existence of leptospiral genus-specific antigens but characteristics of the antigens remain unknown. Haake et al. (1993) firstly identified a gene named as ompLl with a whole size of 963 bp encoding a transmembrane protein with 320 amino acid residuals. By using Southern hybridization, the authors demonstrated the ompLl gene existence in DNAs from multiple serogroups of L. interrogans. In 2000, Haake and his colleagues reported LipL32 gene with 819 bp in size encoding a lipoprotein with 272 amino acid residuals in outer membrane (major outer membrane protein, MOMP) that exists in DNAs of five serovars belonging to four serogroups of L. interrogans.It is well known that epidemic dominant serogroups of L. interrogans in different countries and areas are greatly various. Based on the results of our recent study, in major epidemic serogroups of L. interrogans in China, ompLl gene could be at least divided into three genotypes. ompLl/1 genotype contains serogroups Autumnalis, Grippotyphosa and Sejroe, while ompLl/2 genotype involves serogroups Icterohaemorrhagiae, Canicola, Australis, Pomona and Hebdomadis. L. interrogans serogroups carrying ompLl/3 genotype are not epidemic in our country. The output of recombinant ompLl/1 genotype (30%) was higher than that of recombinant ompLl/2 genotype (20%) and the liters of the rabbit antisera of both the two recombinant expression proteins measured by microscopic agglutination test (MAT) were ranged from 1:16-128. Among the dominant serogroups of L. interrogans in China, lipL32 genes could be divided into two genotypes. HpL32 /I genotype contains ten major L. interrogans serogroups epidemic in China such as Icterohaemorrhagiae, Canicola, Autumnalis, Pomona, Grippotyphosa, Hebdomadis and Sejroe. Besides, the expression output of recombinant lipL32 /I genotype (40%) was much higher than that of HpL32 /2 genotype (10%).Although genetic engineering vaccine possesses many advantages, it hasdisadvantages such as low immunoprotection probably due to single antigen and high cost for production. By using genetic engineering technique to fuse the two different genes of HpL32 /I and ompLl/1 and then to construct expression system of lipL32 /1-ompLl /I fusion gene, it should be a possible way to simplify procedure and decrease cost during production, and... |
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