The aim of this thesis was firstly to investigate the possibility of local antibody in urine samples from HEPS individuals to evaluate the theory that such individuals may develop a protective local anti-HIV-l antibody response, detectable in urine. Since elicitation of mucosal immunity is important in preventing viral infection by sexual transmission, development of a vaccine which is effective for the induction of mucosal immune responses may provide protection to mucosal surfaces against HIV-1 transmission. Transgenic plants expressing foreign protein has been demonstrated to be an inexpensive and easily delivered system for the production of animal and human vaccines which can effectively induce mucosal immune response. The second aim of this work was to develop a transgenic plant system expressing HIV-1 gp160 protein to exploit the feasibility of HIV-1 oral vaccine. The specificity of IgG, IgA and sIgA anti-HIV antibodies to different HIV-1 viral proteins present in paired urine and serum samples from 3 HIV-1 seropositive and 9 HEPS individuals were profiled using Western blot immunoassay. Specific sIgA antibodies to HIV-1 gpl60, p65, gp4l, p31 and p24 were detected in urine or the corresponding vaginal swab samples from HIV-1 seropositive individuals, which suggested that a local mucosal immune response was induced by HIV-1 infection. For samples from HEPS individuals, specific IgG antibodies to HIV-1 gp160, gpl2O and p51, and IgA antibody to HIV-1 p51 were detected in 1 of 9 urine but not the corresponding serum samples, respectively. These results suggested that local mucosal immune responses may be elicited in those HEPS individuals. Furthermore, IgG are the predominant isotype of anti-HIV antibodies present in the genitourinary tract of those HEPS subjects and may be associated with a natural protection mechanism in some individuals.