Biomedical subjects

Gregory T Spear

Publications and source records attributed to Gregory T Spear.

At least 19 recordsLinked to original sources

PubMed2006

HIV infection of mononuclear cells is calcium-dependent.

Strategies that prevent initial HIV infection of cells are greatly needed. In this study, we determined the requirement of divalent cations for HIV infection of and attachment to peripheral blood mononuclear cells (PBMC), which contain several types of HIV-infectable cells-CD4(+) T cells, monocytes and dendritic cells. EDTA, added only during PBMC exposure to HIV, reduced infection by an average of 92%. The reduction of infection by EDTA was accompanied by a reduction in HIV binding to PBMC; R5, X4 and dual-tropic HIV binding to PBMC were inhibited by >85%. EGTA similarly reduced HIV binding to PBMC, while addition of Ca(2+) or Mn(2+), but not Mg(2+), fully restored binding. Virus attachment was inhibited in a dose-dependent manner by trypsin treatment of PBMC, indicating protein involvement in HIV binding. In contrast, mannan or soluble ICAM-1 did not inhibit HIV binding to PBMC. These data indicate that a Ca(2+)-dependent cell-surface protein(s) is responsible for the majority of HIV attachment to and infection of PBMC. Further studies of this are likely to reveal novel strategies to prevent infection of PBMC.

Antiviral Agents↗

PubMed2006

Interaction of human immunodeficiency virus (HIV) glycans with lectins of the human immune system.

Approximately half of the molecular mass of gp120, the receptor-binding envelope protein of human immunodeficiency virus (HIV), consists of N-linked glycans. Nearly half of these glycans are of the high mannose type. These high mannose glycans furnish a rich forest of mannose residues on the virus surface making HIV a prime target for interaction with mannose-specific lectins of the immune system. This review focuses on the known interactions between gp120 and immune system lectins some of which HIV appears to exploit. The effect of variation in glycosylation of gp120, especially with respect to clades of HIV, on binding of immune system lectins is highlighted.

Animals↗

PubMed2005

HIV-inducing factor in cervicovaginal secretions is associated with bacterial vaginosis in HIV-1-infected women.

OBJECTIVE: Certain cervicovaginal lavage (CVL) fluid samples obtained from HIV-1-infected and uninfected women stimulate in vitro HIV-1 replication. This activity, HIV-inducing factor (HIF), changes when CVL fluid is heated. We sought to confirm a previous observation that HIF was associated with bacterial vaginosis (BV). METHODS: HIF was measured in unheated and heated CVL fluid obtained from HIV-1-infected women and compared with the presence of BV by Nugent scores, other genital tract conditions, and cervicovaginal HIV-1 shedding. RESULTS: Among the 295 women studied, 54% of CVL samples had HIF activity and 21% showed heat-stable HIF activity. In adjusted logistic regression, heat-stable HIF was associated with BV (odds ratio [OR]=51.7, 95% confidence interval [CI]: 5.0, 530.7) and with intermediate flora (OR=43.3, 95% CI: 3.6, 521.1); heat-labile HIF was not associated with BV. Neither heat-stable nor heat-labile HIF was associated with other cervicovaginal conditions nor, after controlling for plasma viral load, with genital tract HIV-1 shedding. CONCLUSION: We confirmed the association of HIF with BV and attribute it to the heat-stable component. Heat-stable activity is also associated, although less strongly, with intermediate vaginal flora. We propose that heat-stable HIF is a result of products of BV-associated bacteria.

Adolescent↗

PubMed2005

Induction of tumor necrosis factor- alpha secretion and toll-like receptor 2 and 4 mRNA expression by genital mucosal fluids from women with bacterial vaginosis.

BACKGROUND: Bacterial vaginosis (BV) is associated with complications of pregnancy and increased susceptibility to human immunodeficiency virus (HIV) sexual transmission. METHODS: The ability of genital mucosal fluids from women with BV and of microbial flora associated with BV to induce tumor necrosis factor (TNF)- alpha secretion and Toll-like receptor (TLR) 2 and TLR4 mRNA expression was assessed. RESULTS: Primary peripheral-blood mononuclear cells and THP-1 monocytic cells secreted TNF- alpha in response to cervicovaginal lavage (CVL) samples from women with BV. Mycoplasma hominis and Gardnerella vaginalis also stimulated TNF- alpha secretion. Strikingly, CVL samples from women with BV induced up to 60-fold increases in TLR4 mRNA expression, compared with CVL samples from women without BV and with bacteria not associated with BV. Anti-TNF- alpha antibody blocked increases in TLR4 mRNA expression induced by CVL samples from women with BV, indicating that TNF- alpha plays a critical role in induction of TLR4. Both TLR2 and TLR4 mRNA expression were approximately 60-fold higher in cells isolated from the lumen of the genital tract than in cervical mucosal tissue, but lumen TLR mRNA levels did not change significantly after BV treatment. CONCLUSIONS: These experiments show that genital mucosal fluids and certain bacteria from women with BV stimulate TNF- alpha secretion and TLR4 mRNA expression, suggesting mechanisms whereby BV affects pregnancy and HIV transmission.

Cell Line, Tumor↗

PubMed2005

Relationship of HIV RNA and cytokines in saliva from HIV-infected individuals.

We measured levels of six cytokines and human immunodeficiency virus (HIV) RNA in saliva from HIV-seropositive individuals and compared salivary cytokine levels in HIV-seropositives and seronegatives. All of the six tested cytokines were detected in saliva although interleukin-1beta, interferon-gamma and interleukin-10 were detected more frequently (90%, 68% and 61% of samples, respectively) than interleukin-6, tumor necrosis factor-alpha and tumor necrosis factor-alpha receptor II (2-17%). There was no significant association between cytokine levels in saliva and plasma suggesting that cytokines were produced locally. Interferon-gamma levels were significantly higher in saliva from HIV-seropositives when compared to seronegatives while interleukin-10 levels were lower in seropositive saliva. Interleukin-10 levels were higher in individuals with low CD4 counts in the seropositive group. HIV RNA was detected in 29% of saliva samples from seropositives and there was a significant correlation between saliva and plasma HIV RNA levels. However, HIV RNA levels in saliva were not significantly associated with any of the saliva or plasma cytokine levels or with CD4 cell numbers. This study shows no association between inflammatory cytokine levels and HIV levels in saliva and suggests that saliva HIV levels are more influenced by blood HIV RNA levels than oral inflammation.

CD4 Lymphocyte Count↗

PubMed2005

Mannose binding lectin (MBL) and HIV.

The envelope protein (gp120/gp41) of HIV-1 is highly glycosylated with about half of the molecular mass of gp120 consisting of N-linked carbohydrates. While glycosylation of HIV gp120/gp41 provides a formidable barrier for development of strong antibody responses to the virus, it also provides a potential site of attack by the innate immune system through the C-type lectin mannose binding lectin (MBL) (also called mannan binding lectin or mannan binding protein). A number of studies have clearly shown that MBL binds to HIV. Binding of MBL to HIV is dependent on the high-mannose glycans on gp120 while host cell glycans incorporated into virions do not contribute substantially to this interaction. It is notable that MBL, due to its specificity for the types of glycans that are abundant on gp120, has been shown to interact with all tested HIV strains. While direct neutralization of HIV produced in T cell lines by MBL has been reported, neutralization is relatively low for HIV primary isolates. However, drugs that alter processing of carbohydrates enhance neutralization of HIV primary isolates by MBL. Complement activation on gp120 and opsonization of HIV due to MBL binding have also been observed but these immune mechanisms have not been studied in detail. MBL has also been shown to block the interaction between HIV and DC-SIGN. Clinical studies show that levels of MBL, an acute-phase protein, increase during HIV disease. The effects of MBL on HIV disease progression and transmission are equivocal with some studies showing positive effects and other showing no effect or negative effects. Because of apparently universal reactivity with HIV strains, MBL clearly represents an important mechanism for recognition of HIV by the immune system. However, further studies are needed to define the in vivo contribution of MBL to clearance and destruction of HIV, the reasons for low neutralization by MBL and ways that MBL anti-viral effects can be augmented.

Cell Adhesion Molecules↗

PubMed2005

Relationship of U1 cell HIV-stimulatory activity to bacterial vaginosis and HIV genital tract virus load.

Bacterial vaginosis (BV) has been associated with HIV sexual transmission and increased levels of genital tract HIV RNA. We postulated that BV induces the appearance of substances in the genital tract that stimulate HIV expression locally. To test this, we measured HIV RNA levels in genital mucosal fluid from women with or without BV (defined by Nugent score) and compared them with the ability of those fluids to stimulate HIV expression in the chronically HIV-infected monocytic line U1. The U1 activity was significantly higher in women with BV (median = 1320 pg/ml p24) than in women with normal flora (median = 103 pg/ml p24, p = 0.0001). However, levels of the U1 activity were not significantly associated with levels in the genital tract of HIV RNA. Levels of the U1 activity were also not associated with levels of Gardnerella vaginalis or Mycoplasma hominis in genital fluids, suggesting these bacteria were not the source of the activity. Thus, while these data show a strong association of U1 stimulatory activity with BV, no influence of the U1 activity on genital tract HIV expression was observed.

Cell Line↗

PubMed2005

Mannose-binding lectin binds to Ebola and Marburg envelope glycoproteins, resulting in blocking of virus interaction with DC-SIGN and complement-mediated virus neutralization.

Mannose-binding lectin (MBL), a serum lectin that mediates innate immune functions including activation of the lectin complement pathway, binds to carbohydrates expressed on some viral glycoproteins. In this study, the ability of MBL to bind to virus particles pseudotyped with Ebola and Marburg envelope glycoproteins was evaluated. Virus particles bearing either Ebola (Zaire strain) or Marburg (Musoke strain) envelope glycoproteins bound at significantly higher levels to immobilized MBL compared with virus particles pseudotyped with vesicular stomatitis virus glycoprotein or with no virus glycoprotein. As observed in previous studies, Ebola-pseudotyped virus bound to cells expressing the lectin DC-SIGN (dendritic cell-specific intercellular adhesion molecule 3-grabbing non-integrin). However, pre-incubation of virus with MBL blocked DC-SIGN-mediated binding to cells, suggesting that the two lectins bind at the same or overlapping sites on the Ebola glycoprotein. Neutralization experiments showed that virus pseudotyped with Ebola or Marburg (Musoke) glycoprotein was neutralized by complement, while the Marburg (Ravn strain) glycoprotein-pseudotyped virus was less sensitive to neutralization. Neutralization was partially mediated through the lectin complement pathway, since a complement source deficient in MBL was significantly less effective at neutralizing viruses pseudotyped with filovirus glycoproteins and addition of purified MBL to the MBL-deficient complement increased neutralization. These experiments demonstrated that MBL binds to filovirus envelope glycoproteins resulting in important biological effects and suggest that MBL can interact with filoviruses during infection in humans.

Binding, Competitive↗

PubMed2005

Utility of Amsel criteria, Nugent score, and quantitative PCR for Gardnerella vaginalis, Mycoplasma hominis, and Lactobacillus spp. for diagnosis of bacterial vaginosis in human immunodeficiency virus-infected women.

Bacterial vaginosis (BV) is a clinical syndrome presenting with a malodorous vaginal discharge and increased vaginal pH. Diagnosis has been based on clinical Amsel criteria and direct Gram stain of vaginal secretions. Human immunodeficiency virus (HIV)-infected participants in the Women's Interagency HIV Study contributed cervicovaginal lavage (CVL) samples. Lactobacilli, Gardnerella vaginalis, and Mycoplasma hominis in cervicovaginal lavage samples were quantified by PCR. Gynecologic evaluation included Nugent score and Amsel criterion assessment. We compared the gold standard Nugent score to Amsel criteria and quantitative bacterial PCR for diagnosing BV in 203 CVL samples from women with Nugent scores of 7 to 10 (BV group) and 203 samples from women with BV Nugent scores of 0 to 3 ("No-BV" group). Only 75 of the 203 CVL samples from women with Nugent scores of 7 to 10 met positive Amsel criteria. Increasing levels of G. vaginalis and M. hominis and decreasing levels of lactobacilli were significantly associated with BV by Nugent score. Of the group with Nugent scores of 7 to 10, 83% and 81% had log(10) G. vaginalis counts and log(10) M. hominis counts greater than 6.81 and 4.82, respectively, while only 30% and 31% of the group with Nugent scores of 0 to 3 were above these thresholds, respectively. There was significant overlap in the log(10) lactobacillus counts between the two groups. Utilizing all three log(10) bacterial counts (G. vaginalis, M. hominis, and lactobacilli) in our model improved the sensitivity and specificity to 83% and 78%, respectively, in comparison with Nugent score. In this cohort, Amsel criteria were poorly predictive of BV. PCR quantification of G. vaginalis and M. hominis from CVL is significantly more sensitive than Amsel criteria for diagnosing BV.

DNA, Bacterial↗

PubMed2004

Female genital-tract HIV load correlates inversely with Lactobacillus species but positively with bacterial vaginosis and Mycoplasma hominis.

BACKGROUND: Bacterial vaginosis (BV) is associated with human immunodeficiency virus (HIV) acquisition. We examined the association between BV and BV-associated bacteria and expression of HIV in the female genital tract. METHODS: HIV RNA, lactobacilli, Gardnerella vaginalis, and Mycoplasma hominis in cervicovaginal lavage (CVL) samples were quantified by polymerase chain reaction (PCR). Gynecologic evaluation included Nugent score assessment, Amsel criteria assessment, detection of other genital-tract infections, and dysplasia grading. CD4 cell count, plasma HIV RNA level, and antiretroviral history were obtained. RESULTS: A total of 203 CVL samples from women with Nugent scores of 7-10 (BV group) and 203 samples from women with Nugent scores of 0-3 (no-BV group) were matched by plasma HIV RNA level and analyzed. After controlling for plasma HIV RNA level and Nugent score in univariate analyses, we found that G. vaginalis and M. hominis bacterial counts, Candida vaginitis, and herpes simplex virus (HSV) were positively associated with CVL HIV RNA levels. In multivariate analysis, only lactobacilli bacterial counts (P=.006; inverse association), M. hominis bacterial counts (P=.0001; positive association), Candida vaginitis (P=.007), and HSV (P=.03) were significantly associated with CVL HIV RNA levels. CONCLUSION: Bacteria associated with BV increase genital-tract HIV RNA levels. Quantitative bacterial counts for lactobacilli and M. hominis are better correlates of CVL HIV RNA than are Nugent score or Amsel criteria. Since plasma virus and CD4 cell levels did not differ between the BV and no-BV groups, these data suggest that the bacterial flora associated with BV influence genital-tract HIV shedding.

Adult↗

PubMed2004

Trichomonas vaginalis infection activates cells through toll-like receptor 4.

While Trichomonas vaginalis infection can cause inflammation and influx of leukocytes into the female genital tract, the molecular pathways important in inducing these effects are not known. This study determined if infection with T. vaginalis activates cells through toll-like receptor 4 (TLR4). Genital tract secretions from infected women stimulated TNF-alpha production by cells with functional TLR4 (350 pg/ml) but significantly less by cells that are unresponsive to TLR4 ligands (44 pg/ml, P = 0.001). Secretions collected after clearance of infection also induced significantly lower responses by cells with functional TLR4 (136 pg/ml, P = 0.008). TNF-alpha responses were not reduced by Polymyxin B and did not correlate with beta(2)-defensin levels, indicating that stimulation of cells was not through lipopolysaccharide or beta(2)-defensin. These studies show that T. vaginalis infection results in the appearance in the genital tract of substance(s) that stimulate cells through TLR4, suggesting a mechanism for the inflammation caused by this infection.

Animals↗

PubMed2004

Interaction of mannose-binding lectin with HIV type 1 is sufficient for virus opsonization but not neutralization.

Mannose-binding lectin (MBL), a microbe-recognition protein in serum, binds to high mannose glycans on HIV-1 gp120 and has been reported to neutralize the cell line-adapted strain HIV(IIIB). Because HIV primary isolates (PI) are generally more resistant to neutralization by antibodies and considering that PI are produced in primary cells that could alter the number of high mannose glycans on HIV relative to cell lines, we assessed the ability to MBL to neutralize HIV PI. MBL at concentrations up to 50 microg/ml mediated relatively little neutralization (<20%) of HIV PI infection of peripheral blood mononuclear cells (PBMCs). MBL-neutralizing activity was slightly higher for cell line-adapted HIV infection of the H9 T cell line (up to 64% at 50 microg/ml). However, this effect was specific for H9 cells since MBL did not neutralize cell line-adapted virus infection of PBMCs, HIV PI infection of the GHOST cell line, or VSV pseudotyped with HIV gp160 from cell line-derived virus or PI. In contrast to its low activity in neutralization assays, MBL efficiently bound infectious HIV PI and opsonized HIV PI for uptake by monocytic cells. These results show that both PI and cell line-adapted HIV, despite binding of MBL, are relatively resistant to neutralization by levels of MBL normally present in serum. However, binding and opsonization of HIV by MBL may alter virus trafficking and viral-antigen presentation during HIV infection.

Cell Line↗

PubMed2004

Induction of mucosal and systemic neutralizing antibodies against human immunodeficiency virus type 1 (HIV-1) by oral immunization with bovine Papillomavirus-HIV-1 gp41 chimeric virus-like particles.

Human immunodeficiency virus type 1 (HIV-1) envelope-specific neutralizing antibodies are generated late after initial infection, and the neutralizing antibody response is weak in the infected individuals. Administration of neutralizing antibodies such as 2F5 to HIV-1-infected individuals resulted in reductions in viral loads. Because HIV-1 is transmitted mainly via mucosa and because HIV-specific neutralizing antibodies reduce HIV-1 in infected individuals, a vaccine that can induce both mucosal and systemic HIV-1-specific neutralizing antibodies may be used to prevent and to treat HIV-1 infection. In this study, we made a bovine papillomavirus (BPV) L1-HIV-1 gp41 fusion protein in which ELDKWA of gp41 was inserted into the N terminus of BPV L1 (amino acids 130 to 136). Expression of the fusion protein in insect cells led to the assembly of chimeric virus-like particles (CVLPs). The CVLPs had sizes similar to those of BPV particles and were able to bind to the cell surface and penetrate the cell membrane. Oral immunization of mice with CVLPs induced gp41-specific serum immunoglobulin G (IgG) and intestinal secretory IgA. However, intramuscular immunization with the CVLPs resulted in similar amounts of gp41-specific IgG but low levels of secretory IgA. The antibodies specifically recognized the fixed HIV-1 gp41 on the cell surface. Importantly, the sera and fecal extracts from mice orally immunized with the CVLPs neutralized HIV-1(MN) in vitro. Thus, BPV-HIV-1 gp41 CVLPs may be used to prevent and to treat HIV-1 infection.

AIDS Vaccines↗

PubMed2004

Activation by inflammatory stimuli increases neutrophil binding of human immunodeficiency virus type 1 and subsequent infection of lymphocytes.

Resting neutrophils bind human immunodeficiency virus type 1 (HIV-1) and efficiently transfer infection to lymphocytes. The present study shows that a brief activation by inflammatory stimuli increases the neutrophil binding levels of both R5 and X4 isolates of HIV-1 at least twofold. The binding occurs independently of CD4, gp120, and incubation temperature and is observed with HIV-1 propagated either in lymphocytes or in HEK293 cells. Significantly, HIV-1 bound to the activated neutrophils accelerates the infection of activated lymphocytes compared to free HIV-1 or to HIV-1 bound to resting neutrophils. It is proposed that these events may contribute to the increased risk of HIV-1 transmission at sites of mucosal infection.

CD4 Antigens↗

PubMed2003

Inhibition of DC-SIGN-mediated trans infection of T cells by mannose-binding lectin.

Some dendritic cells (DC) express a cell-surface lectin called 'dendritic cell-specific intracellular adhesion molecule 3 (ICAM-3)-grabbing non-integrin' (DC-SIGN). DC-SIGN has been shown to mediate a type of infection called 'trans' infection, where DC bind human immunodeficiency virus (HIV) and efficiently transfer the virus to T cells. We investigated the possibility that mannose-binding lectin (MBL), a soluble lectin that functions as a recognition molecule in innate immunity and that binds to HIV, could block trans infection mediated by DC-SIGN. Binding studies with glycoprotein (gp)120/gp41-positive and -negative virus preparations suggested that DC-SIGN and MBL bind primarily to glycans on gp120/gp41, as opposed to glycans on host-cell-derived proteins, indicating a close overlap in the binding site of the two lectins and supporting the notion that MBL could prevent binding of HIV to DC-SIGN. Preincubation of X4, R5 or dual-tropic HIV strains with MBL prevented DC-SIGN-mediated trans infection of T cells. The mechanism of MBL blocking trans infection of T cells was at least partly caused by blocking of virus binding to DC-SIGN positive cells. This study shows that MBL prevents DC-SIGN-mediated trans infection of T cells in vitro and suggests that in infected persons, MBL may inhibit DC-SIGN-mediated uptake and spread of HIV.

Binding, Competitive↗

PubMed2003

Glycosylation inhibitors and neuraminidase enhance human immunodeficiency virus type 1 binding and neutralization by mannose-binding lectin.

Mannose-binding lectin (MBL), a C-type lectin component of the human innate immune system, binds to the gp120 envelope glycoprotein of human immunodeficiency virus type 1 (HIV-1). The objective of this study was to assess the effects of inhibitors of endoplasmic reticulum glucosidases and Golgi mannosidase as well as neuraminidase (NA) on the interaction between HIV and MBL. Production of HIV in the presence of the mannosidase I inhibitor deoxymannojirimycin (dMM) significantly enhanced binding of HIV to MBL and increased MBL neutralization of an M-tropic HIV primary isolate. In contrast, culturing HIV in the presence of alpha-glucosidase I and II inhibitors castanospermine and deoxynojirimycin only slightly affected virus binding and neutralization by MBL. Removal of sialic acid from HIV by NA also significantly enhanced virus binding and neutralization by MBL. Treatment of virus grown in the presence of dMM with endoglycosidase F1 substantially reduced binding to MBL, indicating that dMM increased MBL binding by increasing high-mannose carbohydrates on the virus. In contrast, endoglycosidase F1 did not decrease the MBL interaction with NA-treated virus, suggesting that NA exposed novel MBL binding sites. Treatment with dMM increased the immunocapture of HIV by monoclonal antibodies 2F5 and 2G12, indicating that altering the glycosylation of viral glycoproteins increases the accessibility or reactivity of some epitopes. This study shows that specific alterations of the N-linked carbohydrates on HIV gp120/gp41 can enhance MBL-mediated neutralization of virus by strengthening the interaction of HIV-1 with MBL.

1-Deoxynojirimycin↗

PubMed2002

Detection of bacterial vaginosis-related organisms by real-time PCR for Lactobacilli, Gardnerella vaginalis and Mycoplasma hominis.

The aim of this study was to determine the feasibility of detecting bacterial vaginosis (BV)-related organisms in stored genital tract specimens using real-time PCR. Frozen cervicovaginal lavage (CVL) samples from 21 women were analyzed by real-time PCR for the numbers of Mycoplasma hominis, Gardnerella vaginalis and lactobacilli. Lactobacilli organisms were detected in all CVL samples, G. vaginalis was detected in all but one sample, while M. hominis was detected in only six samples. Using the Amsel criteria to define BV, the samples from women with BV had significantly higher numbers of G. vaginalis organisms than samples from women without BV (P=0.004). In contrast, the number of lactobacilli organisms in BV samples was significantly lower (P=0.013). The number of M. hominis organisms was not significantly different between BV-positive and BV-negative samples. A striking relationship was observed where most of the samples contained high numbers of either lactobacilli or G. vaginalis but not both. These results show that it is possible to determine the presence of BV-related organisms in stored genital tract samples by PCR, suggesting that this could be developed into an objective method that could be useful for certain applications.

Cervix Uteri↗

PubMed2002

High mannose glycans and sialic acid on gp120 regulate binding of mannose-binding lectin (MBL) to HIV type 1.

Mannose-binding lectin (MBL) is a C-type lectin of the innate immune system that binds to carbohydrates on the surface of certain microorganisms. Previous studies showed that MBL binds to gp120, the envelope glycoprotein of HIV-1. gp120 is extensively glycosylated, with N-linked complex and high mannose carbohydrates accounting for about half of the molecular weight. The objectives of this study were to determine the types of glycans on gp120 important for MBL binding and to determine if alteration of complex glycans with neuraminidase (NA) could enhance the interaction of MBL with virus. Lectin blot analyses revealed that MBL interacted with recombinant gp120 (rgp120) from both T cell-tropic and M-tropic virus strains. Treatment of rgp120 with endoglycosidase H (eH) or endoglycosidase F1 (eF1) abrogated binding of MBL, but did not decrease binding of wheat germ agglutinin indicating that high mannose and/or hybrid N-linked glycans were required for MBL binding. Removal of sialic acids from rgp120 with NA enhanced MBL binding. Treatment of intact virus from T cell lines or primary isolates with eF1 also significantly decreased HIV binding to MBL, while treatment with NA substantially increased binding. Treatment of virus with both eF1 and NA did not decrease binding compared to NA alone suggesting that NA treatment exposed binding sites on gp120 that are not high mannose glycans. These studies provide evidence that MBL binds to HIV via high mannose carbohydrates on gp120 and shows that the interaction of MBL with virus is regulated by sialylation.

HIV Envelope Protein gp120↗