Imperial College London

Abbey Evans

Faculty of MedicineDepartment of Infectious Disease

Research Technician/Project Administrator







Norfolk PlaceSt Mary's Campus





Publication Type

7 results found

Cheeseman HM, Carias AM, Evans AB, Olejniczak NJ, Ziprin P, King DF, Hope TJ, Shattock RJet al., 2016, Expression profile of human Fc receptors in mucosal tissue: implications for antibody-dependent cellular effector functions targeting HIV-1 transmission, PLOS One, Vol: 11, ISSN: 1932-6203

The majority of new Human Immunodeficiency Virus (HIV)-1 infections are acquired via sexual transmission at mucosal surfaces. Partial efficacy (31.2%) of the Thai RV144 HIV-1 vaccine trial has been correlated with Antibody-dependent Cellular Cytotoxicity (ADCC) mediated by non-neutralizing antibodies targeting the V1V2 region of the HIV-1 envelope. This has led to speculation that ADCC and other antibody-dependent cellular effector functions might provide an important defense against mucosal acquisition of HIV-1 infection. However, the ability of antibody-dependent cellular effector mechanisms to impact on early mucosal transmission events will depend on a variety of parameters including effector cell type, frequency, the class of Fc-Receptor (FcR) expressed, the number of FcR per cell and the glycoslyation pattern of the induced antibodies. In this study, we characterize and compare the frequency and phenotype of IgG (CD16 [FcγRIII], CD32 [FcγRII] and CD64 [FcγRI]) and IgA (CD89 [FcαR]) receptor expression on effector cells within male and female genital mucosal tissue, colorectal tissue and red blood cell-lysed whole blood. The frequency of FcR expression on CD14+ monocytic cells, myeloid dendritic cells and natural killer cells were similar across the three mucosal tissue compartments, but significantly lower when compared to the FcR expression profile of effector cells isolated from whole blood, with many cells negative for all FcRs. Of the three tissues tested, penile tissue had the highest percentage of FcR positive effector cells. Immunofluorescent staining was used to determine the location of CD14+, CD11c+ and CD56+ cells within the three mucosal tissues. We show that the majority of effector cells across the different mucosal locations reside within the subepithelial lamina propria. The potential implication of the observed FcR expression patterns on the effectiveness of FcR-dependent cellular effector functions to impact on the ini

Journal article

Vamvaka E, Evans A, Ramessar K, Krumpe LRH, Shattock RJ, O'Keefe BR, Christou P, Capell Tet al., 2016, Cyanovirin-N produced in rice endosperm offers effective pre-exposure prophylaxis against HIV-1BaL infection in vitro, Plant Cell Reports, Vol: 35, Pages: 1309-1319, ISSN: 1432-203X

Cyanovirin-N (CV-N) is a lectin with potent antiviral activity that has been proposed as a component of microbicides for the prevention of infection with Human immunodeficiency virus (HIV). The production of protein-based microbicide components requires a platform that is sufficiently economical and scalable to meet the demands of the large at-risk population, particularly in resource poor developing countries. We, therefore, expressed CV-N in rice endosperm, because the dried seed is ideal for storage and transport and crude extracts could be prepared locally and used as a microbicide component without further purification. We found that crude extracts from rice seeds expressing up to 10 µg CV-N per gram dry seed weight showed dose-dependent gp120 binding activity, confirming that the protein was soluble, correctly folded and active. The recombinant lectin (OSCV-N) reduced the infectivity of HIV-1BaL (an R5 virus strain representing the majority of transmitted infections) by ~90 % but showed only weak neutralization activity against HIV-1RF (representative of X4 virus, rarely associated with transmission), suggesting it would be highly effective for pre-exposure prophylaxis against the vast majority of transmitted strains. Crude extracts expressing OSCV-N showed no toxicity towards human cells at working dilutions indicating that microbicide components produced in rice endosperm are safe for direct application as topical microbicides in humans.

Journal article

Vamvaka E, Arcalis E, Ramessar K, Evans A, O'Keefe BR, Shattock RJ, Medina V, Stöger E, Christou P, Capell Tet al., 2016, Rice endosperm is cost-effective for the production of recombinant griffithsin with potent activity against HIV, Plant Biotechnology Journal, Vol: 14, Pages: 1427-1437, ISSN: 1467-7652

Protein microbicides containing neutralizing antibodies and antiviral lectins may help to reduce the rate of infection with human immunodeficiency virus (HIV) if it is possible to manufacture the components in large quantities at a cost affordable in HIV-endemic regions such as sub-Saharan Africa. We expressed the antiviral lectin griffithsin (GRFT), which shows potent neutralizing activity against HIV, in the endosperm of transgenic rice plants (Oryza sativa), to determine whether rice can be used to produce inexpensive GRFT as a microbicide ingredient. The yield of OSGRFT in the best-performing plants was 223 μg/g dry seed weight. We also established a one-step purification protocol, achieving a recovery of 74% and a purity of 80%, which potentially could be developed into a larger-scale process to facilitate inexpensive downstream processing. OSGRFT bound to HIV glycans with similar efficiency to GRFT produced in Escherichia coli. Whole-cell assays using purified OSGRFT and infectivity assays using crude extracts of transgenic rice endosperm confirmed that both crude and pure OSGRFT showed potent activity against HIV and the crude extracts were not toxic towards human cell lines, suggesting they could be administered as a microbicide with only minimal processing. A freedom-to-operate analysis confirmed that GRFT produced in rice is suitable for commercial development, and an economic evaluation suggested that 1.8 kg/ha of pure GRFT could be produced from rice seeds. Our data therefore indicate that rice could be developed as an inexpensive production platform for GRFT as a microbicide component.

Journal article

Santra S, Tomaras GD, Warrier R, Nicely NI, Liao HX, Pollara J, Liu P, Alam SM, Zhang R, Cocklin SL, Shen X, Duffy R, Xia SM, Schutte RJ, Pemble Iv CW, Dennison SM, Li H, Chao A, Vidnovic K, Evans A, Klein K, Kumar A, Robinson J, Landucci G, Forthal DN, Montefiori DC, Kaewkungwal J, Nitayaphan S, Pitisuttithum P, Rerks-Ngarm S, Robb ML, Michael NL, Kim JH, Soderberg KA, Giorgi EE, Blair L, Korber BT, Moog C, Shattock RJ, Letvin NL, Schmitz JE, Moody MA, Gao F, Ferrari G, Shaw GM, Haynes BFet al., 2015, Human Non-neutralizing HIV-1 Envelope Monoclonal Antibodies Limit the Number of Founder Viruses during SHIV Mucosal Infection in Rhesus Macaques., Plos Pathogens, Vol: 11, ISSN: 1553-7374

HIV-1 mucosal transmission begins with virus or virus-infected cells moving through mucus across mucosal epithelium to infect CD4+ T cells. Although broadly neutralizing antibodies (bnAbs) are the type of HIV-1 antibodies that are most likely protective, they are not induced with current vaccine candidates. In contrast, antibodies that do not neutralize primary HIV-1 strains in the TZM-bl infection assay are readily induced by current vaccine candidates and have also been implicated as secondary correlates of decreased HIV-1 risk in the RV144 vaccine efficacy trial. Here, we have studied the capacity of anti-Env monoclonal antibodies (mAbs) against either the immunodominant region of gp41 (7B2 IgG1), the first constant region of gp120 (A32 IgG1), or the third variable loop (V3) of gp120 (CH22 IgG1) to modulate in vivo rectal mucosal transmission of a high-dose simian-human immunodeficiency virus (SHIV-BaL) in rhesus macaques. 7B2 IgG1 or A32 IgG1, each containing mutations to enhance Fc function, was administered passively to rhesus macaques but afforded no protection against productive clinical infection while the positive control antibody CH22 IgG1 prevented infection in 4 of 6 animals. Enumeration of transmitted/founder (T/F) viruses revealed that passive infusion of each of the three antibodies significantly reduced the number of T/F genomes. Thus, some antibodies that bind HIV-1 Env but fail to neutralize virus in traditional neutralization assays may limit the number of T/F viruses involved in transmission without leading to enhancement of viral infection. For one of these mAbs, gp41 mAb 7B2, we provide the first co-crystal structure in complex with a common cyclical loop motif demonstrated to be critical for infection by other retroviruses.

Journal article

Cheeseman HM, Klein K, Evans A, King D, Shattock RJet al., 2014, Functional Assessment of Antibody Activity in Mucosal Tissue Explant and Cellular Inhibition Assays, AIDS RESEARCH AND HUMAN RETROVIRUSES, Vol: 30, Pages: A230-A230, ISSN: 0889-2229

Journal article

Ekeruche-Makinde JN, Evans A, Herrera C, Charles K, Shattock Ret al., 2014, Exploring Innovative Approaches to the Formulation of Microbicides to Boost Antiretroviral Drug Delivery and Activity at Mucosal Sites, AIDS RESEARCH AND HUMAN RETROVIRUSES, Vol: 30, Pages: A150-A151, ISSN: 0889-2229

Journal article

Forbes CJ, Mccoy CF, Murphy DJ, Woolfson AD, Moore JP, Evans A, Shattock RJ, Malcolm RKet al., 2014, Modified Silicone Elastomer Vaginal Gels for Sustained Release of Antiretroviral HIV Microbicides, JOURNAL OF PHARMACEUTICAL SCIENCES, Vol: 103, Pages: 1422-1432, ISSN: 0022-3549

Journal article

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