Murine immune response to recombinant HIV1 p24 core protein following subcutaneous, intraperitoneal and intravenous immunisation

The murine immune response to baculovirus-produced human immunodeficiency virus type-1 (HIV-1)p24 was examined after injection by three different routes: subcutaneously (s.c.), intraperitoneally (i.p.) and intravenously (i.v.). Both antigen-specific T-cell proliferation and serum antibody were induced by i.p. injection. In contrast, s.c. and i.v. injection of antigen resulted in specific antibody generation alone. Lympho-proliferative responses seen after i.p. injection were confined to splenocytes, and were greater after a low dose of antigen than after a high dose. p24-specific proliferation was not detected in lymph node cells. CD4:CD8 ratios were normal in lymph nodes and spleen at all times, irrespective of the dose or route of administration. p24-specific serum IgG antibodies were detected in all animals after the second injection of antigen. After s.c. and i.v. administration of high doses of antigen, the median antibody titres continued to rise after a third injection, but plateaued in animals injected by the i.p. route. In contrast, low doses of antigen given i.p. increased the median titre during and after the course of four injections. A low antigen dose given s.c. resulted in a plateau of median titre between the third and fourth injections. In i.v.-injected animals the median titre decreased between the third and fourth injections. IgG1 p24-specific antibodies were detected in all immunized mice, whereas IgM antibodies were detectable only following i.p. injection of antigen.