Immune responses in mice induced with a TSOL18 recombinant Mycobacterium smegmatis vaccine of Taenia solium

Abstract

Objective To observe humoral and cellular immune responses induced in mice by a TSOL18 recombinant Mycobacterium smegmatis (MS) vaccine of Taenia solium. Methods Sixty specific pathogen-free (SPF) Kunming mice (18-22 g, half male and half female) were divided into 3 groups by random number table method, 20 mice in each group. One group was administered with recombinant MS-TSOL18 vaccine, one group was administered with MS as control, and one group was administered phosphate buffer saline (PBS) as control. Kunming mice were vaccinated once every two weeks for 2 times through intragastric administration. At 0, 2, 4, 6, and 8 weeks after immunization, blood sample was collected and serum was separated. The levels of IgG and IgG2a in serum were detected using enzyme linked immunosorbent assay (ELISA). The spleen was separated to prepare spleen suspension. The proliferation of spleen lymphocyte with the stimulation of a specific antigen was detected by CCK-8. The levels of interleukin (IL)-2 and IL-4 in spleen cell culture supernatant with the stimulation of a specific antigen were detected by ELISA. Results Compared with MS control group (IgG: 0.160 ± 0.019, 0.187 ± 0.038, 0.193 ± 0.050, 0.170 ± 0.005; IgG2a: 0.213 ± 0.010, 0.198 ± 0.012) and PBS control group (IgG: 0.159 ± 0.015, 0.184 ± 0.029, 0.191 ± 0.025, 0.165 ± 0.018; IgG2a: 0.198 ± 0.032, 0.178 ± 0.025), the levels of specific IgG (0.310 ± 0.034, 0.391 ± 0.029, 0.443 ± 0.030, 0.373 ± 0.021) in recombinant MS-TSOL18 vaccine group increased at 2, 4, 6, and 8 weeks after immunization (P < 0.05), the levels of specific IgG2a (0.446 ± 0.056, 0.339 ± 0.026) in recombinant MS-TSOL18 vaccine group increased at 6 and 8 weeks after immunization (P < 0.05), and reached the highest level by the 6th week. After antigen stimulation, compared with MS and PBS control groups, the levels of spleen lymphocyte proliferation increased at 2, 4, 6, and 8 weeks after immunization (P < 0.05), and reached the highest level by the 6th week. After antigen stimulation, compared with MS and PBS control groups, the levels of IL-2 and IL-4 in spleen lymphocyte culture supernatant increased at 2, 4, 6, and 8 weeks after immunization (P < 0.05), and reached the highest level by the 6th and 4th weeks, respectively. Conclusion The recombinant MS-TSOL18 vaccine of Taenia solium might induce mice to produce humoral and cellular immune responses. Key words: Taenia solium; TSOL18; Recombinant Mycobacterium smegmatis vaccine; Immune response; Mice