final program.qxd - Parallels Plesk Panel

PP 2.14
CD4 Independent Transmission of HIV
A.H. Bandivdekar, Shilpa Velhal and
V. P. Raghavan
National Institute for Research in Reproductive Health,
J. M. Street, Parel, Mumbai 400 012 INDIA
Objectives
To identify and characterize CD4 independent HIV receptor on spermatozoa.
Methods
Human sperm proteins were solubilized using 1% Triton X-100. The HIV binding protein
was identified by Western blot analysis of sperm proteins using gp120 HIV env
glycoprotein, antibodies to gp120 and alkaline phosphatase labeled antirabbit IgG. The
differential expression of 160kDa protein in the sperm samples from different individuals
was studied by Western blot and flow cytometric analysis. cDNA encoding 160kDa protein
was isolated from human testicular cDNA and sequenced.
Results
Western blot analysis of sperm proteins demonstrated the specific binding of gp120 as
well as cell free HIV to 160kDa protein band. 160kDa protein has been shown to be
distinct from conventional CD4 receptor. The preliminary studies demonstrated the
differential expression of this protein in sperm samples from individual donors and the
samples which are devoid of this protein did not show the binding of gp120 HIV envelope
glycoprotein to any of the protein in sperm extract. cDNA sequencing of 160kDa HIV
receptor protein showed sequence homology with human mannose receptor.
Conclusion : Human immunodeficiency virus (HIV) is known to be primarily transmitted
through sexual route. Although initially seminal leukocytes and cell free virus were
suspected to be the source of infection, later it is realized that HIV binds and enter in to
spermatozoa and the sperm bound virus facilitate the infection into urogenital cells such
as Langerhan cells and Macrophages. Moreover the studies using monkey model
demonstrated that the due to acidic vaginal pH the survival of seminal leukocyte as well
as cell free virus is difficult and the cell free virus need for efficient infection through
vaginal route is very high as compared to that of systemic route. Hence understanding the
role of spermatozoa in transmission of HIV is important. However the modality of HIV entry
into spermatozoa was not known due to absence of conventional CD4 receptors on
sperm. In an attempt to understand the mechanism of HIV transmission, CD4 independent
160kDa HIV receptor protein present on the spermatozoa has been identified for the first
time, which showed the sequence homology to human mannose receptor. The differential
expression of this protein on the sperm samples from different individuals may be
associated with the risk of sexual transmission of HIV. These observations suggest the
need for renewed efforts towards the development of modalities in prevention of sexual
transmission of HIV and also need to understand mechanism of CD4 independent
interaction of HIV.
POSTERS
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