Cellular HSF1 expression is induced during HIV-1 infection by activation of its promoter mediated through the cooperative interaction of HSF1 and viral Nef protein.

The Human Immunodeficiency Virus-1 (HIV-1) tends to activate cellular promoters driving expression of pro-viral genes by complex host-virus interactions for productive infection. We have previously demonstrated that expression of such a positive host factor HSF1 (heat shock factor 1) is elevated during HIV-1 infection; however, the mechanism remains to be elucidated. In the present study, we therefore examined whether HSF1 promoter is induced during HIV-1 infection leading to up-regulation of hsf1 gene expression. We mapped the putative transcription start site (TSS) predicted by Eukaryotic promoter database and deletion constructs of the predicted promoter region were tested through luciferase assay to identify the active promoter. The 347 bp upstream to 153 bp downstream region around the putative TSS displayed the highest activity and both Sp1 (stimulating protein 1) and HSF1 itself were identified to be important for its basal activation. Activity of HSF1 promoter was further stimulated during HIV-1 infection in CD4+ T cells, where interestingly the HSF1-site itself seems to play a major role. In addition, HIV-1 protein Nef (negative factor) was also observed to be responsible for the virus-mediated induction of hsf1 gene expression. Chromatin-immunoprecipitation assays further demonstrate that Nef and HSF1 are co-recruited to the HSF1-binding site and cooperatively act on this promoter. The interplay between host HSF1 and viral Nef on HSF1 promoter eventually leads to increase in HSF1 expression during HIV-1 infection. Understanding the mechanism of HSF1 up-regulation during HIV-1 infection might contribute to future antiviral strategies as HSF1 is a positive regulator of virus replication.

DNAJB8 facilitates autophagic-lysosomal degradation of viral Vif protein and restricts HIV-1 virion infectivity by rescuing APOBEC3G expression in host cells.

HSP40/DNAJ family of proteins is the most diverse chaperone family, comprising about 49 isoforms in humans. Several reports have demonstrated the functional role of a few of these isoforms in the pathogenesis of various viruses, including HIV-1. Our earlier study has shown that several isoforms of HSP40 get significantly modulated at the mRNA level during HIV-1 infection in T cells. To explore the biological role of these significantly modulated isoforms, we analyzed their effect on HIV-1 gene expression and virus production using knockdown and overexpression studies. Among these isoforms, DNAJA3, DNAJB1, DNAJB7, DNAJC4, DNAJC5B, DNAJC5G, DNAJC6, DNAJC22, and DNAJC30 seem to positively regulate virus replication, whereas DNAJB3, DNAJB6, DNAJB8, and DNAJC5 negatively regulate virus replication. Further investigation on the infectivity of the progeny virion demonstrated that only DNAJB8 negatively regulates the progeny virion infectivity. It was further identified that DNAJB8 protein is involved in the downregulation of Vif protein, required for the infectivity of HIV-1 virions. DNAJB8 seems to direct Vif protein for autophagic-lysosomal degradation, leading to rescue of the cellular restriction factor APOBEC3G from Vif-mediated proteasomal degradation, resulting in enhanced packaging of APOBEC3G in budding virions and release of less infective progeny virion particles. Finally, our results also indicate that during the early stage of HIV-1 infection, enhanced expression of DNAJB8 promotes the production of less infective progeny virions, but at the later stage or at the peak of infection, reduced expression of DNJAB8 protein allows the HIV-1 to replicate and produce more infective progeny virion particles.

Zipper interacting protein kinase (ZIPK) is a negative regulator of HIV-1 replication that is restricted by viral Nef protein through proteasomal degradation.

Human immunodeficiency virus-1 (HIV-1) infection leads to the development of acquired immunodeficiency syndrome (AIDS). To establish a productive infection, HIV-1 hijacks the cellular machinery and modulates various physiological processes to propagate itself. The pathways altered by HIV-1 include cell cycle, autophagy, apoptosis, cell stress pathways, immune response, antiviral response, etc. Zipper interacting protein kinase (ZIPK) is a member of the death-associated protein kinase (DAPK) family of proteins, known to be one of the key regulators of cell death and cell survival pathways. ZIPK is also involved in regulating many cellular processes that are altered during HIV-1 infection; thus, we have explored the functional role of ZIPK in HIV-1 infection. Our results show that ZIPK protein expression is downregulated during HIV-1 infection in Nef dependent manner. Overexpression of ZIPK leads to downregulation in LTR-driven gene expression and virus production, whereas ZIPK knockdown induces viral gene expression and replication. HIV-1 promoter activity is reportedly enhanced by Nef-mediated activation of some transcription factors like NFκB and STAT3. ZIPK is reported to inhibit the STAT3 activity by phosphorylating it at ser-727. Our results show that STAT3 (ser-727) phosphorylation is decreased upon overexpression of Nef with simultaneous downregulation of ZIPK expression. We finally show that HIV-1 Nef interacts with ZIPK and induces its proteasomal degradation. Overall, our data suggests that Nef is involved in downregulation of ZIPK thereby increasing the virus production through rescue of STAT3 activity.

Synthesis and anti-HIV activity of a new isoxazole containing disubstituted 1,2,4-oxadiazoles analogs.

Continuing on our antiviral drug discovery research, we intended to diversify our lead anti-HIV-1 inhibitor by non-classical isosteric replacement of amide to 1,2,4-oxadiazoles. The resulting molecules isoxazole-1,2,4-oxadiazole analogs were synthesized using mild bases in ethanol under microwave irradiation. The anti-HIV potential was checked in human CD4+ reporter cell lines, TZM-bl and CEM-GFP, at the highest non-cytotoxic concentration (HNC), demonstrating that 3-((3-(p-tolyl)isoxazol-5-yl)methyl)-1,2,4-oxadiazole and 3-((3-(4-chlorophenyl)isoxazol-5-yl)methyl)-1,2,4-oxadiazole inhibit HIV-1 replication significantly and could be considered as a new lead candidate against HIV-1.

The barley lectin, horcolin, binds high-mannose glycans in a multivalent fashion, enabling high-affinity, specific inhibition of cellular HIV infection.

N-Linked glycans are critical to the infection cycle of HIV, and most neutralizing antibodies target the high-mannose glycans found on the surface envelope glycoprotein-120 (gp120). Carbohydrate-binding proteins, particularly mannose-binding lectins, have also been shown to bind these glycans. Despite their therapeutic potency, their ability to cause lymphocyte proliferation limits their application. In this study, we report one such lectin named horcolin (Hordeum vulgare lectin), seen to lack mitogenicity owing to the divergence in the residues at its carbohydrate-binding sites, which makes it a promising candidate for exploration as an anti-HIV agent. Extensive isothermal titration calorimetry experiments reveal that the lectin was sensitive to the length and branching of mannooligosaccharides and thereby the total valency. Modeling and simulation studies demonstrate two distinct modes of binding, a monovalent binding to shorter saccharides and a bivalent mode for higher glycans, involving simultaneous interactions of multiple glycan arms with the primary carbohydrate-binding sites. This multivalent mode of binding was further strengthened by interactions of core mannosyl residues with a secondary conserved site on the protein, leading to an exponential increase in affinity. Finally, we confirmed the interaction of horcolin with recombinant gp120 and gp140 with high affinity and inhibition of HIV infection at nanomolar concentrations without mitogenicity.

A comprehensive profile of genomic variations in the SARS-CoV-2 isolates from the state of Telangana, India.

The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing COVID-19 has rapidly turned into a pandemic, infecting millions and causing 1 157 509 (as of 27 October 2020) deaths across the globe. In addition to studying the mode of transmission and evasion of host immune system, analysing the viral mutational landscape constitutes an area under active research. The latter is expected to impart knowledge on the emergence of different clades, subclades, viral protein functions and protein-protein and protein-RNA interactions during replication/transcription cycle of virus and response to host immune checkpoints. In this study, we have attempted to bring forth the viral genomic variants defining the major clade(s) as identified from samples collected from the state of Telangana, India. We further report a comprehensive draft of all genomic variations (including unique mutations) present in SARS-CoV-2 strain in the state of Telangana. Our results reveal the presence of two mutually exclusive subgroups defined by specific variants within the dominant clade present in the population. This work attempts to bridge the critical gap regarding the genomic landscape and associate mutations in SARS-CoV-2 from a highly infected southern region of India, which was lacking to date.

Monitoring and predicting regional land use and land cover changes in an estuarine landscape of India.

Deciphering land use and land cover (LULC) change patterns, identifying the variables that act as the major driving forces of change, and predicting possible changes are necessary tools of decision support for policymakers. Estuarine landscapes world over are under extreme pressure of developmental activities because of their resources. The developmental activities lead to unforeseen changes in the traditional land use practices, making it necessary for investigation of the possible outcomes. The present study aims to study the changing pattern of LULC in the East Godavari River Estuarine Ecosystem (EGREE) landscape during 1977-2015 using temporal satellite data and to predict the possible LULC changes by 2029. Cellular Automata-Markov model (CAMM) with and without the multi-criteria evaluator (MCE) and the multi-layer perceptron (MLP) models were used for future LULC prediction. Between 1977 and 2015, mangroves were converted to aquaculture (5.81 km2) on the landward side and were also lost to submergence at the seaward side (15 km2). All of the coastal scrub (69 km2) was lost to beach clearing. Over this period, the aquaculture area rose to 177 km2. The CAMM with MCE was found to yield better predictions. A further rise was predicted in aquaculture (16%), built-up (30%), and Casuarina plantations (28%) by 2029. The study highlighted the LULC change patterns in EGREE, an important estuarine landscape of India. The information generated in this study can act as baseline information for the stakeholders and policy makers in decision-making of developmental projects, land acquisition, and diversion of agricultural land to non-agricultural purposes.

Abdominoperineal Tunnel Crafted with Alken's Telescopic Dilators: A Novel Technique!

BACKGROUND: Abdomino-perineal pull through procedure needs perineal dissection and for that swap of supine to prone may be necessary. To avoid that as well as to avoid neuro-muscular damage; we are describing a simple minimal invasive procedure with help of Alken's telescopic dilators. PATIENTS & METHODS: We created abdomino-perineal tunnel with Alken's telescopic dilators to bring down the lumen of intestine in perineum in eight patients. RESULTS: Operative time happened to be less and procedure found to be less traumatic. All the eight patients had satisfactory outcome. CONCLUSIONS: Actually, we have repurposed the Alken's dilator for creation of abdomino-perineal tunnel or track to get benefit of minimal dissection of perineum during pull-through procedure as well as to avoid neuro-muscular damage.

Factors Accountable for Unabated Obstruction Following Pyeloplasty.

PURPOSE: Split renal function (SFR) and frusemide washout (FWO) are assessed by the DTPA renogram to measure the renal parenchymal functions as well as the evidence of obstruction, both for diagnosis and to treat the pelviureteric junction obstruction. In good number of renal units, both these parameters remain unaltered even after surgery and cause anguish to parents and referring physicians and are usually attributed toward "defective pyeloplasty." In this study, we have tried to single out the bona fide responsible factor for the bad outcome; either the nonreversible kidney or the restenosis of pyeloplasty. PATIENTS AND METHODS: We studied file of 69 patients in whom a double "J" (DJ) stent was left in situ for internal drainage for a duration of 8 weeks in the postoperative period. DTPA scans were performed preoperative, at 8 weeks with a stent in place, and at 12 and 24 months postremoval of the stent to assess renal function. RESULTS: In our study, 45 patients (65.2%) showed improvement either in SRF or in FWO or in both after 8 weeks following pyeloplasty and 24 of 69 units (34.8%) did not show any change in renal function with DJ stent in place. Only in six units (8.7%), out of 69 units had deterioration of renal function after removal of DJ stent. CONCLUSIONS: In our opinion, no improvement of renal function found in 24 units (34.8%) even with internal drainage with DJ indicates irreversible renal damage. In 45 units (65.2%), renal function reversed after pyeloplasty and DJ stent. However, after the removal of the DJ, functions deteriorated in six units (8.7%) due to restenosis following pyeloplasties.

N-p-Tosyl-L-phenylalanine chloromethyl ketone (TPCK) inhibits HIV-1 by suppressing the activity of viral protease.

Human Immunodeficiency Virus (HIV), the etiological agent for Acquired Immunodeficiency Syndrome (AIDS), continues to kill humans despite stupendous advances in antiviral research. With the presently available combination antiretroviral therapeutic arsenal, AIDS is now a manageable disease but with no cure available till date. The development of novel antivirals consumes an extensive amount of time and resources. Hence, repurposing of the established gold standard molecules for their anti-HIV application is enormously advantageous. In this study, we report that N-p-Tosyl-L-phenylalanine chloromethyl ketone (TPCK) inhibits HIV-1 replication in a highly-conserved manner. Further, TPCK inhibits HIV-1 replication at the late stages of its life cycle by impeding viral protease (PR) enzyme activity. Additionally, our results demonstrate that the combination of TPCK with established HIV-1 PR inhibitors shows significant synergistic inhibitory potential, suggesting the potential use of TPCK in cART regimen. Collectively, we report the anti-HIV activity of TPCK, which should be further characterized for its translational applications.

Recent Advances in the Development of Integrase Inhibitors for HIV Treatment.

PURPOSE OF THE REVIEW: The complex multistep life cycle of HIV allows it to proliferate within the host and integrate its genome in to the host chromosomal DNA. This provirus can remain dormant for an indefinite period. The process of integration, governed by integrase (IN), is highly conserved across the Retroviridae family. Hence, targeting integration is not only expected to block HIV replication but may also reveal new therapeutic strategies to treat HIV as well as other retrovirus infections. RECENT FINDINGS: HIV integrase (IN) has gained attention as the most promising therapeutic target as there are no equivalent homologues of IN that has been discovered in humans. Although current nano-formulated long-acting IN inhibitors have demonstrated the phenomenal ability to block HIV integration and replication with extraordinary half-life, they also have certain limitations. In this review, we have summarized the current literature on clinically established IN inhibitors, their mechanism of action, the advantages and disadvantages associated with their therapeutic application, and finally current HIV cure strategies using these inhibitors.

Insight into Posterior Urethral Valve from Our Experience: Paradigm Appended to Abate Renal Failure.

OBJECTIVE: The objective of the study was to share our experience of management of posterior urethral valve (PUV) and to suggest a paradigm to impede upstaging of chronic kidney disease (CKD) and prevent end-stage renal failure (ESRF). PATIENTS AND METHODS: We have treated 332 patient of PUV from March 2005 to April 2016, Of which 272 case records had adequate data to be analyzed. The mean age was 2.48 years (range: 1 day-18 years). We did primary fulguration in 231 patients, of which five patients needed bilateral ureterostomy for obstinate high creatinine level. The remaining 36 patients had primary fulguration done elsewhere. RESULTS: The mean duration of follow-up was 7.8 years (range 3-14 years). In the end of this study, 10 patients had down staging in CKD, 36 patients had up staging in CKD, and 9 patients ended in ESRF (3.8%). CONCLUSIONS: Detection of deterioration of renal function with creatinine clearance along with identifying the causes of deterioration and necessary interventions would help to arrest upstaging of CKD otherwise that might end in ESRF. From this study and reviewing the literature, we presume that the rhabdosphincter spasm underneath actually renders bladder outlet obstruction, and cusps of PUV, particularly in neonates, amplify the obstruction, following that bladder outlet obstruction cascades detrusor hypertrophy, bladder neck hypertrophy/obstructions, and ureterovesical junction obstruction/reflux, causing gradual damage to the bladder and upper tract and deterioration of renal function as a consequence.

Impact of biomass burning on regional aerosol optical properties: A case study over northern India.

The present study examines the spatial, seasonal and inter annual variation of biomass burning and its impact on regional aerosol optical properties over Northern India using multi-satellite aerosol observations: Active fire points, AOD (550 nm) and AE (550-860 nm) from MODIS retrievals during January 2003-December 2017 and AAOD (388 nm), SSA (388 nm) and AI from OMI UV retrievals during January 2005-December 2017. Results from MODIS active fire count statistics indicate an increase in the number of fire occurrences (average 1477 fires per year) over India in a period of 15 years (2003-2017). The dominant fire seasons are (i) Pre-monsoon (March to May) accounting to more than 45% and (ii) Post-Monsoon having 24% of total annual fires counts. However, the crop residue burning hotspot region located in Punjab and Haryana, constitutes 26% of the total fires in India. At an average, 15456 (77.08%) fire counts were reported during the paddy season, whereas 3296 (16.44%) fire counts during wheat season respectively. The crop residue burning over the northwest IGP (Punjab) significantly affect the aerosol optical properties locally as well in the downwind regions during post-monsoon season i.e., crop residue fires increased by 4% (170 fires per year) with corresponding AOD, AAOD & AI increased by 8%, 9% & 11% respectively. The satellite observation shows large gradient of aerosol parameters from north-west to south-east along the Himalayan foot-hills which indicates the regional transport of smoke aerosols over the region. This is also supported by ground based AOD observations at four locations (Patiala, Delhi, Dehradun and Kanpur) and Black Carbon measurements at two locations (Patiala and Dehradun). The climatological averaged values of ground based AOD550 for Patiala, Delhi, Dehradun and Kanpur are 0.52 ±â€¯0.26, 0.75 ±â€¯0.40, 0.45 ±â€¯0.24 and 0.57 ±â€¯0.29 respectively whereas BC concentrations are 8.43 ±â€¯3.14 µg m-3 & 3.36 ±â€¯1.26 µg m-3 for Patiala & Dehradun respectively. Comparison of MODIS derived AOD agrees well with ground based AODs (overall R = 0.86 and RMSE = 0.14). In addition, CALIPSO shows the maximum amount of biomass burning smoke aerosols present within the atmospheric boundary layer and some cases it extending up to 2-3 km altitudes. The smoke aerosol transport pathways originated from crop residue burning were analyzed using Hysplit forward trajectories. The results reveal that majority of smoke aerosols are transported to eastern IGP, central India and adjacent oceanic regions during post-monsoon season.

Cyclin F/FBXO1 Interacts with HIV-1 Viral Infectivity Factor (Vif) and Restricts Progeny Virion Infectivity by Ubiquitination and Proteasomal Degradation of Vif Protein through SCFcyclin F E3 Ligase Machinery.

Cyclin F protein, also known as FBXO1, is the largest among all cyclins and oscillates in the cell cycle like other cyclins. Apart from being a G2/M cyclin, cyclin F functions as the substrate-binding subunit of SCFcyclin F E3 ubiquitin ligase. In a gene expression analysis performed to identify novel gene modulations associated with cell cycle dysregulation during HIV-1 infection in CD4+ T cells, we observed down-regulation of the cyclin F gene (CCNF). Later, using gene overexpression and knockdown studies, we identified cyclin F as negatively influencing HIV-1 viral infectivity without any significant impact on virus production. Subsequently, we found that cyclin F negatively regulates the expression of viral protein Vif (viral infectivity factor) at the protein level. We also identified a novel host-pathogen interaction between cyclin F and Vif protein in T cells during HIV-1 infection. Mutational analysis of a cyclin F-specific amino acid motif in the C-terminal region of Vif indicated rescue of the protein from cyclin F-mediated down-regulation. Subsequently, we showed that Vif is a novel substrate of the SCFcyclin F E3 ligase, where cyclin F mediates the ubiquitination and proteasomal degradation of Vif through physical interaction. Finally, we showed that cyclin F augments APOBEC3G expression through degradation of Vif to regulate infectivity of progeny virions. Taken together, our results demonstrate that cyclin F is a novel F-box protein that functions as an intrinsic cellular regulator of HIV-1 Vif and has a negative regulatory effect on the maintenance of viral infectivity by restoring APOBEC3G expression.

HSP70 binding protein 1 (HspBP1) suppresses HIV-1 replication by inhibiting NF-κB mediated activation of viral gene expression.

HIV-1 efficiently hijacks host cellular machinery and exploits a plethora of host-viral interactions for its successful survival. Identifying host factors that affect susceptibility or resistance to HIV-1 may offer a promising therapeutic strategy against HIV-1. Previously, we have reported that heat shock proteins, HSP40 and HSP70 reciprocally regulate HIV-1 gene-expression and replication. In the present study, we have identified HSP70 binding protein 1 (HspBP1) as a host-intrinsic inhibitor of HIV-1. HspBP1 level was found to be significantly down modulated during HIV-1 infection and virus production inversely co-related with HspBP1 expression. Our results further demonstrate that HspBP1 inhibits HIV-1 long terminal repeat (LTR) promoter activity. Gel shift and chromatin immunoprecipitation assays revealed that HspBP1 was recruited on HIV-1 LTR at NF-κB enhancer region (κB sites). The binding of HspBP1 to κB sites obliterates the binding of NF-κB hetero-dimer (p50/p65) to the same region, leading to repression in NF-κB mediated activation of LTR-driven gene-expression. HspBP1 also plays an inhibitory role in the reactivation of latently infected cells, corroborating its repressive effect on NF-κB pathway. Thus, our results clearly show that HspBP1 acts as an endogenous negative regulator of HIV-1 gene-expression and replication by suppressing NF-κB-mediated activation of viral transcription.

Gene expression profiling reveals Nef induced deregulation of lipid metabolism in HIV-1 infected T cells.

Human Immunodeficiency Virus-1 (HIV-1) encodes a 27 kDa Negative Factor or Nef protein, which is increasingly proving to be a misnomer. Nef seems to be crucial for AIDS progression as individuals infected with nef-deleted strain of HIV were reported to become Long Term Non Progressors (LTNP). These findings necessitate tracing of Nef's footprint on landscape of cellular transcriptome favoring HIV-1 pathogenesis. We have tried to explore effect of Nef on cellular gene expression profile in conjunction with rest of HIV-1 proteins. Our results show that 237 genes are differentially regulated due to the presence of Nef during infection, which belong to several broad categories like "signaling", "apoptosis", "transcription" and "lipid metabolism" in gene ontology analysis. Furthermore, our results show that Nef causes disruption of lipid content in HIV-1 infected T cells. Molecular inhibitors of lipid metabolism like Atorvastatin and Ranolazine were found to have profound effect on wild type virus as compared to nef-deleted HIV-1. Thus our results suggest that interference in lipid metabolism is a potential mechanism through which Nef contributes in enhancing HIV-1 pathogenesis.

Assessment of land surface temperature and heat fluxes over Delhi using remote sensing data.

Surface energy processes has an essential role in urban weather, climate and hydrosphere cycles, as well in urban heat redistribution. The research was undertaken to analyze the potential of Landsat and MODIS data in retrieving biophysical parameters in estimating land surface temperature & heat fluxes diurnally in summer and winter seasons of years 2000 and 2010 and understanding its effect on anthropogenic heat disturbance over Delhi and surrounding region. Results show that during years 2000-2010, settlement and industrial area increased from 5.66 to 11.74% and 4.92 to 11.87% respectively which in turn has direct effect on land surface temperature (LST) and heat fluxes including anthropogenic heat flux. Based on the energy balance model for land surface, a method to estimate the increase in anthropogenic heat flux (Has) has been proposed. The settlement and industrial areas has higher amounts of energy consumed and has high values of Has in all seasons. The comparison of satellite derived LST with that of field measured values show that Landsat estimated values are in close agreement within error of ±2 °C than MODIS with an error of ±3 °C. It was observed that, during 2000 and 2010, the average change in surface temperature using Landsat over settlement & industrial areas of both seasons is 1.4 °C & for MODIS data is 3.7 °C. The seasonal average change in anthropogenic heat flux (Has) estimated using Landsat & MODIS is up by around 38 W/m(2) and 62 W/m(2) respectively while higher change is observed over settlement and concrete structures. The study reveals that the dynamic range of Has values has increased in the 10 year period due to the strong anthropogenic influence over the area. The study showed that anthropogenic heat flux is an indicator of the strength of urban heat island effect, and can be used to quantify the magnitude of the urban heat island effect.

Identification of the potential regions of Epap-1 that interacts with V3 loop of HIV-1 gp120.

Early pregnancy associated protein-1 (Epap-1), a 90kDa glycoprotein present in first trimester placental tissue, inhibits HIV-1 entry through interaction with HIV-1 gp120 at V3 and C5 regions. In the present study, we have identified the specific 32 mer region of Epap-1 that can interact with V3 loop. This was achieved by docking between Epap-1 molecular model and gp120 and studying the interaction of peptides with gp120 in vitro. Out of four peptides analyzed, two peptides (P-2 and P-3) showed significant interaction with V3 domain (N=8; N=7) of gp120. In the studies conducted using soluble gp120 and virus, peptide P-2 has shown conserved interaction at V3 loop regions recognized by 257D and F425 antibodies and higher anti-viral activity. Also, P-2 inhibited cell fusion mediated dye transfer between gp120 expressing HL2/3 and CD4 expressing Sup T1 cells suggesting its inhibition of viral entry, which is further confirmed by its action on HIV infection mediated by Tat activated beta gal expression in TZM-bl cells. Further optimization of P-2 peptide showed that the anti-viral activity and gp120 interaction residues lie in the N-terminal region of the peptide. These results together suggest that P-2 inhibits viral entry through specific interaction at V3 loop region.