Search

Antibody-dependent cellular phagocytosis (ADCP) has been implicated in protection against HIV-1. However, methods for measuring ADCP currently rely on the phagocytosis of gp120- or gp41-coated beads that do not reflect physiologically relevant conformations of the viral envelope glycoprotein or the size of a virus-infected cell. We therefore developed a novel approach for measuring ADCP of HIV-infected cells expressing natural conformations of Env. A monocytic cell line (THP-1 cells) or primary human monocytes were incubated with a CD4+ T cell line that expresses eGFP upon HIV-1 infection in the presence of antibodies and ADCP was measured as the accumulation of eGFP+ material by flow cytometry. The internalization of HIV-infected cells by monocytes was confirmed visually by image-capture flow cytometry. Cytoskeletal remodeling, pseudopod formation and phagocytosis were also observed by confocal microscopy. We found that potent broadly neutralizing antibodies (bnAbs), but not non-neutralizing antibodies (nnAbs), mediate efficient phagocytosis of cells infected with either primary or lab-adapted HIV-1. A nnAb to a CD4-inducible epitope of gp120 (A32) failed to enable ADCP of HIV-infected cells but mediated efficient phagocytosis of gp120-coated beads. Conversely, a bnAb specific to intact Env trimers (PGT145) mediated potent ADCP of HIV-infected cells but did not facilitate the uptake of gp120-coated beads. These results underscore the importance of measuring ADCP of HIV-infected cells expressing physiologically relevant conformations of Env and show that most antibodies that are capable of binding to Env trimers on virions to neutralize virus infectivity are also capable of binding to Env on the surface of virus-infected cells to mediate ADCP. Author summary: In addition to neutralizing virus-infectivity, antibodies that bind to the human immunodeficiency virus (HIV-1) envelope glycoprotein (Env) can recruit cells of the immune system to eliminate productively infected cells through a process known as antibody-dependent cellular phagocytosis (ADCP). ADCP occurs when an antibody bound to Env on the surface of an HIV-infected cell is recognized by a phagocytic cell, such as a monocyte, macrophage or neutrophil, and the phagocytic cell engulfs and destroys the virus-infected cell. ADCP has been implicated in protection against HIV-1. However, methods for measuring ADCP currently do not reflect physiologically relevant conformations of Env or the size of a virus-infected cell. We therefore developed a novel assay for measuring ADCP of HIV-infected cells expressing natural conformations of Env. Using this approach, we found that potent broadly neutralizing antibodies (bnAbs) that are capable of binding to functional Env trimers on virions to block HIV-1 infectivity can also mediate efficient phagocytosis of HIV-infected cells. However, non-neutralizing antibodies (nnAbs) that by definition cannot block viral infectivity exhibit little or no ADCP. These results stand in marked contrast to previous methods for measuring ADCP based on the internalization of beads coated with recombinant Env proteins, which show greater antibody-dependent phagocytosis by nnAbs. These results show that most antibodies that are able to neutralize HIV-1 infectivity are also able to direct the phagocytosis of HIV-infected cells and illustrate the importance of measuring ADCP of virus-infected cells expressing physiologically relevant conformations of Env. [ABSTRACT FROM AUTHOR]

Eliciting neutralizing antibodies is thought to be a key activity of a vaccine against human immunodeficiency virus (HIV). However, a number of studies have suggested that in addition to neutralization, interaction of IgG with Fc gamma receptors (FcγR) may play an important role in antibody-mediated protection. We have previously obtained evidence that the protective activity of the broadly neutralizing human IgG1 anti-HIV monoclonal antibody (MAb) b12 in macaques is diminished in the absence of FcγR binding capacity. To investigate antibody-dependent cellular cytotoxicity (ADCC) as a contributor to FcγR-associated protection, we developed a nonfucosylated variant of b12 (NFb12). We showed that, compared to fully fucosylated (referred to as wild-type in the text) b12, NFb12 had higher affinity for human and rhesus macaque FcγRIIIa and was more efficient in inhibiting viral replication and more effective in killing HIV-infected cells in an ADCC assay. Despite these more potent in vitro antiviral activities, NFb12 did not enhance protection in vivo against repeated low-dose vaginal challenge in the simian-human immunodeficiency virus (SHIV)/macaque model compared to wild-type b12. No difference in protection, viral load, or infection susceptibility was observed between animals given NFb12 and those given fully fucosylated b12, indicating that FcγR-mediated activities distinct from FcγRIIIa-mediated ADCC may be important in the observed protection against SHIV challenge.

Introduction The Thai phase III RV144 vaccine trial, which tested the ALVACHIV (vCP1521) prime and bivalent clade B/E recombinant gp120 boost vaccine regimen, showed an estimated vaccine efficacy (VE) of [...], The phase III RV144 HIV-1 vaccine trial estimated vaccine efficacy (VE) to be 31.2%. This trial demonstrated that the presence of HIV-1-specific IgG-binding Abs to envelope (Env) V1V2 inversely correlated with infection risk, while the presence of Env-specific plasma IgA Abs directly correlated with risk of HIV-1 infection. Moreover, Ab-dependent cellular cytotoxicity responses inversely correlated with risk of infection in vaccine recipients with low IgA; therefore, we hypothesized that vaccine-induced Fc receptor-mediated (FcR-mediated) Ab function is indicative of vaccine protection. We sequenced exons and surrounding areas of FcR-encoding genes and found one FCGR2C tag SNP (rs114945036) that associated with VE against HIV-1 subtype CRF01_AE, with lysine at position 169 (169K) in the V2 loop (CRF01_AE 169K). Individuals carrying CC in this SNP had an estimated VE of 15%, while individuals carrying CT or TT exhibited a VE of 91%. Furthermore, the rs114945036 SNP was highly associated with 3 other FCGR2CSNPs (rs138747765, rs78603008, and rs373013207). Env-specific IgG and IgG3 Abs, IgG avidity, and neutralizing Abs inversely correlated with CRF01_AE 169K HIV-1 infection risk in the CT- or TT carrying vaccine recipients only. These data suggest a potent role of Fc-γ receptors and Fc-mediated Ab function in conferring protection from transmission risk in the RV144 VE trial.

The relationship between opera and gay subcultures, lifestyle practices and consumerism is noted by cultural critics and musicologists is explored initially through a review of the existing literature before concentrating on the striking affinities in the discursive construction of both cultural forms. Both opera and homosexuality are stigmatized and marginalized in their respective rationalizing 'scientific' domains of musicology and sexology.

PHC471 Evans D (2004) Behind the headlines: sexual health implications for nursing ethics and practice. Primary Health Care. 14, 8, 40-49. Date of acceptance: September 8 2004. Aims and intended [...]