Development Of Engineering Vaccines Based On Protective Antigens 45W-4B And TSO18 From Taenia Solium Oncosphere

Cysticercosis is an important zoonosis caused by Taenia solium larval cysticercus cellulosae that can infect intermediate hosts such as pigs or human, which is a major public health problem in most areas of China, especially in minority regions, and a great potential threat to human security. This disease, whose prevention is always an obstacle for veterinarians mainly because of limitation of protective antigens, is known as an economic disease for it attributes not only to great economic loses but also to decrease of international competition on meat products. The success of commercialization of a recombinant 45W vaccine against Taenia ovis provides a bright way to development of such a vaccine against cysticercosis.In the studies, we attempt to develop an effective vaccine based on candidates 45W-4B and TSO18 through evaluation of protection of recombinant antigens in experimental animals.Taenia solium eggs were collected and total RNA was extracted from hatched and activated eggs in vitro. Genes 45W-4B and TSO18, which showed high homology with the published, were cloned and predicted with regard to their structure traits using web sources. The truncated 45W-4B with removal of a signal peptide at N terminal and 19 hydrophobic amino acids at C terminal, designed as 45W-4BX, was amplified by PCR according to predictive results. The interest fragments TSO18 and 45W-4BX were ligated with an expression vector pGEX-4T-l with the same cohesive ends, transformed into competent bacteria BL₂1 and identified with enzyme restriction and PCR and sequencing. Soluble 45W-4BX and TSO18 in the form of inclusive bodies were detected on SDS-PAGE, induced under suitable conditions of temperature and concentration of IPTG. Western blot result indicated that they could be recognized by both sera from pig infected by early developed cysticercus cellulosae and cysticercosis patients.To evaluate the efficacy of protection through lymphocyte proliferation and specific antibody level at different infective periods using MTT method and ELISA, respectively, and cyst determined 90 days postinfection, purified antigens 45W-4BX, TSO18 and GST and cysticercus cellulosae coarse extract were immunized pigs, which were experimentally challenged with 25000 eggs 28 days postimmunization, and 206 was used as adjuvant. Data suggested that antibody level would start to raise and reach at peak 15 and 45 days postimmunization, respectively. MTT analysis indicated that a little proliferation of lymphocyte existed postimmunization and peaked at 10th days after challenge. Trials in vitro certified that complements seemed involved in killing effects of antigens 45W-4BX and TSO18 on oncospheres. Moreover, animal experiments showed the groups immunized with recombinant proteins alone were a 94% and 95% reduction in the number of cysticerci, respectively. Level...