Until now unfortunately no safe effective vaccine

Until now, unfortunately, no safe, effective vaccine against HIV-1/AIDS has been found [16], [17]. Therefore, the development of safe, effective vaccines is a top priority in HIV/AIDS research field. Accordingly, to investigate the interactions between HIV vaccines or inhibitors and their corresponding target molecules is very important for understanding the antiviral mechanisms of vaccines or inhibitors. Recently, atomic force microscopy (AFM) has been widely applied in biological and viral studies [18], [19], [20]. AFM also has been used to image HIV viral particles and HIV-infected lymphocytes [21], [22]. Chang et al. investigated the HIV-1 gp120–receptor interactions in living Varlitinib australia [23]. More recently, the kinetics of gp41 (HIV fusion protein) interaction with lipid membranes was detected by AFM [24]. To date, however, there are no reported AFM studies on interaction forces between HIV inhibitors (e.g. sCD4, anti-CD4 or anti-gp120 antibody, etc.) and their target molecules. In this study, we recruited AFM force measurement to detect the sCD4–gp120 interaction and gp120 or CD4 antigen–antibody interaction.
Materials and methods
Results
Discussion
Introduction HIV is primarily transmitted via the sexual route, with females being disproportionately affected compared to males [1]. In the female, the lower reproductive tract represents the initial site of contact with HIV infected semen [2], [3], [4], [5]. In the vagina, the target cells infected include the immune cells – the CD4+ T cells, dendritic cells and macrophages located in the sub-epithelium. The multilayered (25–40 layer thick) vaginal epithelium which is CD4 negative, separates the incoming virus from the underlying immune cells [2], [6], [7], [8], [9]. HIV's travelogue in crossing the multi-layered epithelial barrier is hitherto unknown. While it is plausible that the interdigitating langerhan cells of the vagina may extend their processes to sample antigen from the lumen [10], the virus must also breach through several layers of impervious epithelium, to gain access to sub-epithelial immune cells [8], [9], [10]. The epithelial cells are refractory to HIV entry [10], [11], [12], and do not support productive infection, with transcytosis reported at a very low extent [13]. This implies that HIV transmission in vagina does not employ the classic replication based mechanisms. However, HIV particles have been identified in the sub-epithelial cells [2], [8], and also between cells of the stratified epithelium [3], [4], [12], suggesting that HIV must use alternate strategies to breach the epithelium. We have previously reported that HIV gp120 binds to vaginal epithelial cells with high affinity, and binding could be displaced in the presence of excess unlabeled ligand [14]. In vivo, HIV gp120 is known to alter a multitude of events and signaling pathways to induce a cascade of deleterious molecular and biological effects by binding to different cell types [15]. HIV gp120 binds to several receptors on vaginal epithelial cells such as gp340, syndecans, human mannose receptor and α4β7 integrins [2], [14]. The vaginal epithelium is CD4 negative and also lacks the classic CXCR4 and CCR5 coreceptors. While induction of MMPs was previously demonstrated by us [14] to occur via HIV gp120 binding to human mannose receptor in vaginal epithelial cells, the signaling events downstream of HIV gp120 binding to other receptors or hitherto unknown binding proteins remains an area to be explored. In the context of HIV and its effects, till date, several microarray based studies have been published, including the effects of HIV gp120 on peripheral blood mononuclear cells and natural killer cells [15], [16], [17], [18]. Several studies have provided an understanding that HIV and its proteins alter the normal physiological functions of cells [19], [20], [21].
Materials and methods
Results
Discussion HIV gp120 is a pleiotrophic molecule which binds to cell surface receptors and mediates downstream signaling effects. Several of the HIV gp120 – epithelial interactions, described in this study are novel, while some of the genes have also been previously reported to be associated with HIV infection. The biological effects of gp120 signaling in different cell types have been demonstrated to be highly divergent [15]. In T cells, gp120 upregulates genes involved in cell cycle [18], while in NK cells opposite effects of apoptosis are induced [17]. The effects of HIV gp120 on the molecular repertoire have been demonstrated to be cell type dependent. In response to gp120 treatment, LIF transcript has been reported to be downregulated in PBMCs while an upregulation was observed in MDMs [18]; in our studies LIF was also upregulated in vaginal cells. While PKC is downregulated in Vk2/E6E7 cells and in Jurkat T cells [27], there is induction of PKC in primary endothelial cells [28]. While it is formally possible that some residual contaminants in our HIV gp120 (Immunodiagnostics) preparation (estimated to be <5%), could contribute to such differences; this possibility seems less likely, as the microarray signatures observed in the Vk2/E6E7 cells in response to gp120, are close to that observed in other cell types [15], [16], [17], [18], [29], [30], [31]. Also, we have previously demonstrated that the binding of HIV gp120 to Vk2/E6E7 cells is highly specific, of high affinity and exhibits saturatable binding kinetics (Kd = 1.4 ± 0.2 nM) [14]. Vaginal epithelial cells express several receptors that bind to HIV gp120 including gp340, syndecans, integrins and hMR. In the current study, we present a global snapshot of the downstream gene expression profiles in the gp120 treated vaginal epithelial cells, and discuss their physiological significance in the vaginal transmission of HIV.