The goal of this thesis is to design and implement a modern parser generator. The result is a program that reads description of some context-free LALR(1) grammar and semantic actions from an input file. To output files the program generates source codes in several target modern object-oriented programming languages for implementation of the syntax analyzer which, when parsing the language corresponding to the given grammar, executes the given semantic actions. Powered by TCPDF (www.tcpdf.org)

Syftet med detta projekt var att konstruera en mindre variant av pQlacZ-1 för att senare kunna använda den som reportervektor i Ideonella dechloratans. pQlacZ-1 är en plasmid som är 17,1 kbp stor, som skulle kunna användas som reportervektor i  Ideonella dechloratans för att kunna undersöka olika promotorsekvenser. Detta är möjligt eftersom pQlacZ-1 är en broad host range plasmid och saknar promotorsekvensen för lacZ genen. Ett problem med pQlacZ-1 är dess storlek vilket gör den svår att transformera, och då speciellt i Ideonella dechloratans som är svår att transformera överhuvudtaget. En stor del av projektet har lagts på att ta reda på hur pQlacZ-1 ser ut i detalj, då detta inte finns väl beskrivet. Även efter denna studie saknas information om ett fragment för att få en helt klar bild över hur plasmiden är uppbyggd. Efter att ha ställt upp en hypotes om hur plasmiden ser ut så identifierades ett område som kunde klyvas bort och det var fragmentet med lacA och lacY. Detta gjordes  genom en dubbelklyvning med SalI och BstBI. Den nya mindre varianten av plasmiden har jag valt att kalla pQlacZ-1cc och den ska teoretiskt sett vara ca 13427 bp stor, vilket bör göra den lättare att jobba med. Ytterligare arbete behövs för att verifiera konstruktionen i pQlacZ-1cc. / The aim with this project was to design a smaller version of pQlacZ-1 in order to later use it as a reporter vector in Ideonella dechloratans.  pQlacZ-1 is a plasmid that is 17,1 kbp big, which might be used as a reporter vector in Ideonella dechloratans to investigate different promoter sequences. This is possible because pQlacZ-1 is a broad host range plasmid and lacks the promoter sequence of the lacZ gene. A problem with pQlacZ-1 is its size which makes it difficult to transform, and especially in Ideonella dechloratans which is difficult to transform at all. A large part of the project has been about finding out how pQlacZ-1 looks like in detail, as this is not well described. Even after this study information about one fragment is missing to get a completely clear picture of how the plasmid is constructed. After formulation of a hypothesis about how the plasmid is constructed, a section that could be removed was identified. The part of pQlacZ-1 that was removed was the lacA and lacY. This was done by a double digestion with SalI and BstBI. The new smaller version of the plasmid, is called pQlacZ-1cc. Theoretically it should be about 13427 bp, which should make it easier to work with. Additional work is required to verify the design of pQlacZ-1cc.

Leukemia is one of the most deadly diseases, responsible for the highest number of childhood cancer cases. Immunoglobulin-containing and proline-rich receptor-1 (IGPR-1) is a newly identified protein found to play an important role in human colon cancer and angiogenesis. The overall goal of this project was to assess IGPR-1 expression in leukemia cell lines and investigate its possible function in the NF-κB pathway, specifically the role of inhibitor of nuclear factor kappa-B kinase subunit beta (IKKβ) in the phosphorylation of IGPR-1. The NF-κB pathway, among others, plays a critical role in human-T-cell leukemia virus type 1 (HTLV-1) infected T-cells. Our preliminary results indicated that IGPR-1 is expressed in leukemia cell lines at variable levels. Further experiments demonstrated that IKKβ is involved in the phosphorylation of IGPR-1 as treatment of HEK-293 cells ectopically expressing IGPR-1 with an IKKβ inhibitor decreased IGPR-1 phosphorylation at Ser220. Likewise, cells treated with lipopolysaccharide (LPS), which is known to activate IKKβ, also stimulated the phosphorylation of IGPR-1 at Ser220. However, transfection of IGPR-1/HEK293 cells with Tax, an oncogene encoded by HTLV-1, decreased phosphorylation of IGPR-1 at Ser220. Taken together, our data indicates that activation of IKKβ in the NF-κB pathway stimulates phosphorylation of IGPR-1. / 2020-06-17T00:00:00Z

Type II diabetes is a major cause of blindness according to the World Health Organization (WHO, 2018). Diabetics are at risk of developing corneal diseases such as recurrent abrasions, ulcers, and erosions due to dysfunctional wound healing. Corrective surgeries or corneal transplants may be considered as a treatment in some, but not all, cases. The purinoreceptor P2X7 has been shown to be involved in cell-cell communication and in the restructuring of cytoskeletal actin, a necessary process for cell migration in wound healing. P2X7 relies on the binding of extracellular ATP for activation. Panx1 is a transmembrane protein whose primary role is for the release of intracellular ATP into the extracellular space. In healthy corneal epithelium, Panx1 localizes to the wound edge and forms clusters with the P2X7, which augments the wound healing response. This thesis looks at the localization of Panx1 in pre-diabetic murine corneal tissue. It was found that Panx1 is less expressed and does not localize to the wound edge to the extent as control corneas, therefore, creating less clusters with P2X7. Furthermore, preliminary studies that inhibit Panx1 with probenecid reduce the communication between cells, which is hypothesized as critical for migration of the tissue sheet and proper wound healing. / 2019-12-17T00:00:00Z

Being a Dissertation presented in fulfilment of the requirement governing the Degree of Master of Science in The School of Medicine, University of the Witwatersrand / Interleukin 1 (IL - 1) is a macrophage factor that exerts control over T cell activation. The experimental work presented in this dissertation consists of studies on IL - 1 production by monocytes which can be used as an in vitro correlate for monocyte function, as well as the effect of IL - 1 on immature T cells, that is, thymocytes. In accomplishing the studies presented in this dissertation, a two stage assay was employed. Firstly IL - 1 containing supernatants were produced by stimulated human peripheral blood adherent cells and secondly, the IL - 1 supernatants were assayed on mouse thymocyctes in which these supernatants caused mitogenesis. / IT2018

Thesis (Ph.D.)--University of the Witwatersrand, Faculty of Health Sciences, 2012. / The development of an effective HIV-1 vaccine is critical in mitigating the global HIV epidemic. Understanding the interplay between host immune functions, such as cellular memory differentiation, activation, inflammatory cytokine production and the virus, may provide key insight into anti-HIV immunity that can inform vaccine development. This PhD aims at understanding and identifying T cell memory, functional profiles and the effect of immune activation on in vivo HIV-1 control during primary/early infection. Furthermore, this study aims to examine and understand the potential mechanisms related to immune activation during primary HIV-1 infection. Use was made of a unique cohort of individuals recruited during primary HIV-1 infection and using a battery of assays to characterize and identify properties and mechanisms of T cell reactivity and activation. Multiparameter flow cytometry was used to measure memory differentiation (CD27 and CD45RO), activation (CD38, HLA-DR), proliferation (Ki67), and multiple cellular functions (CD107, IFNγ, IL-2, MIP-1β and TNFα) of total and antigen-specific CD4+ and CD8+ T cells from 15 HIV-1 and CMV-coinfected individuals followed over 15 months of HIV-1 infection. Plasma samples were used to measure markers associated with intestinal permeability (LBP, sCD14, I-FABP and IgM EndoCAb) and inflammation (IL-1β, IL-6, IL-7, IL-10, IL-12p70, TNFα and MCP-1). The differentiation profile of HIV-Gag specific memory CD4+ and CD8+ T cells was found to be mainly characterized by an early differentiated (ED) memory phenotype relative to CMV- specific CD4+ and CD8+ T cells. Moreover, the proportion of HIV-specific ED-memory CD4+ T cells inversely associated with viraemia, suggesting that HIV-1 antigen burden could be shaping the differentiation of HIV-specific memory CD4+ T cells during primary infection. Primary HIV-1 infection was also characterized by significantly elevated levels of activated and proliferating total and HIV-specific memory CD4+ and CD8+ T cells, which positively correlated with viraemia. Furthermore, upon sorting of total activated memory CD4+ T cells, these cells harboured more gag provirus DNA than non-activated memory cells, suggesting that activated memory CD4+ T cells support ongoing HIV-1 replication. When examining the relationship between memory differentiation and activation markers, the level of T cell activation was equally expanded across the different memory CD4+ T cell subpopulations, suggesting that memory differentiation of CD4+ T cells was unlikely driven per se by the level of T cell activation. In addition, when teasing out events that may result in T cell activation during primary HIV-1 infection using statistical models, plasma markers of microbial translocation and inflammation were found to correlate with immune activation. The lack of these associations in HIV-uninfected controls suggests that microbial translocation and inflammation were unlikely causative. Analysis of the polyfunctional profile of memory T cells during primary HIV-1 infection showed that HIV-specific CD4+ and CD8+ T cell responses are less polyfunctional relative to CMV-specific memory CD4+ and CD8+ T cell responses. Furthermore, the polyfunctional status of HIV-specific CD4+ T cells significantly correlated with viraemia at 3 months post-infection, indicating that the polyfunctionality of memory CD4+ T cells is likely driven by HIV-1 antigenemia. Overall, these observations suggest that HIV-1 antigenic burden appears to be a central driver of memory differentiation, activation/inflammation and polyfunctionality of T cells. Given the impact of HIV-1 viraemia on immune activation and memory T cell dysfunction (as measured by limited polyfunctional HIV-specific responses), preventing high levels of viral replication, with a vaccine or other early interventions may serve as an important strategy for delaying HIV-1 disease progression.

A Thesis Submitted to the School of Public Health, Faculty of Health Sciences University of the Witwatersrand, Johannesburg, South Africa, in fulfilment of the requirements for the Degree of Doctor of Philosophy 15 June 2017 / Background HIV infection has remained a major global health burden since its discovery in 1983 and Sub-Saharan Africa remains the region hardest hit by the HIV/AIDS pandemic. The HIV pandemic continues to ravage most parts of Southern African countries, current prevalence between 10-20%. Individuals worldwide differ in their degree of susceptibility to HIV infection and genetic polymorphisms play a major role. Mannose Binding Lectin (MBL) is one such immunological factor found in serum/plasma, it is a normal liver-derived protein and is a key component of the innate immune defence system. MBL deficiency, due to mutations in the MBL2 gene and promoter region, leading to decreased plasma/serum MBL concentration, characterised by defective opsonisation activities of the innate immune system and increased susceptibility to infections including HIV-1 and schistosomiasis. Rationale While there is a lot of advancement in HIV prevention and treatment in Southern African countries, there is still need to investigate host genetic molecules in adults and mother-baby pairs that could be playing a role in HIV-1 transmission/acquisition, disease progression and survival. It was imperative to carry out this study because of the need to quantify the burden of MBL deficiency in this Zimbabwean adult and PMTCT study populations. Alsoto contribute to the knowledge gap on the role of MBL deficiency in HIV-1 transmission, disease progression and survival in African populations in adults and children. The available literature shows that the majority of studies on the association of MBL deficiency and HIV-1 infection in adults and children have been done on populations outside the African continent. There is dearth of information on the role of MBL in this era when access to ART has greatly improved even in developing countries like Zimbabwe. This will be the second study that will assess MBL2 genes and promoter typing in mother-infant pairs in HIV vertical transmission/acquisition. This study aimed to identify and explore potential biomarkers for susceptibility to HIV infection and disease progression. We assessed role of MBL deficiency in HIV-1 and schistosoma infections in Zimbabwean adults enrolled in the Mupfure Schistosomiasis and HIV Cohort (MUSH Cohort) (Paper 1).We also assessed the role of MBL deficiency on HIV progression and survival in this African adult population. We hypothesized that MBL deficiency has a role to play in HIV infection by increasing HIV disease progression and decreasing survival (Paper 2). We also determined prevalence of MBL deficiency, as estimated by MBL2 haplotypes among Zimbabwean mothers and their children aged 9-18 months old as well as its association with risk of HIV-1 infection and vertical transmission from their HIV positive mothers (Paper 3). Main Aim The broad objective of this study was to determine the relationship between MBL deficiency and HIV infection in an adult population of males and females and among mother-infant pairs in Zimbabwe. Study Specific Objectives 1. To determine the prevalence of MBL deficiency among the Zimbabwean adult population. 2. To determine the relationship of MBL deficiency with HIV infection among the Zimbabwean adult population. 3. To determine the effect of MBL deficiency on disease progression and survival among the Zimbabwean adult population. 4. To determine prevalence of MBL deficiency among mothers and their infants in a Zimbabwean population. 5. To determine the relationship between MBL deficiency and HIV transmission from mother to child in a Zimbabwean population. Methods DNA and plasma samples for MBL and HIV analysis were collected from the 379 adult males and females from the MUSH cohort and stored dried blood samples from 622 mother infant pairs from a national PMTCT survey. HIV-1, S. haematobium and S. mansoni infections were determined at baseline using HIV commercial kits and parasitologically respectively. Plasma MBL concentration was measured by ELISA and MBL2 genotypes determined by PCR. We calculated and compared the proportions of plasma MBL deficiency, MBL2 structural variant alleles B (codon 54A>G), C (codon 57A>G), and D (codon 52T>C) as well as MBL2 promoter variants -550(H/L), -221(X/Y) and +4(P/Q) between HIV-1 and schistosoma co-infection and control groups using Chi Square test (Paper 1). We also assessed the role of MBL deficiency on HIV disease progression and survival inthe adult (MUSH) cohort.We analysed blood samples for MBL levels, MBL2 genotypes, HIV-1 status, viral load and CD4+ T cell counts (Paper 1). Participants were followed up for 3 years wherein the endpoints were measured at baseline, 6 weeks, 3, 6, 12, 24 and 36 months. Disease progression was measured as the rate of decline in CD4+ T cell counts and the rate of increase in HIV viral load (Paper 2). Generalised Estimating Equations (GEE) models were used to compare rates of change of the CD4+ T cell count and viral load measurements over the three-year follow-up period. The role of plasma MBL deficiency and MBL2 genetic variants on survival over the 3-year period were estimated using the Cox proportional hazard models. Regression analysis was used to test for interaction and confounding between MBL deficiency, MBL2 genetic variance, age and sex. We used the Wald Chi-square statistic to choose between full and nested models. We also assessed MBL2 polymorphisms in Zimbabwean HIV positive mothers and their children enrolled in a national PMTCT survey carried out in 2012. MBL deficiency was defined as presence of A/O and O/O genotypes in the mothers and their children. We extracted DNA from two dried blood spots for 622 mothers and infant pairs using the Gene Extract and Amp kit reagents. MBL2 Exon 1 genotypes and promoter region alleles -221(X/Y) and -550(H/L) SNP were detected by pyrosequencing. Differences in distribution frequency between HIV infected and uninfected children, of the MBL2 genotypes, promoter region variants and MBL2 haplotypes, were determined by the Chi square test or Fisher’s exact tests (Paper 3). Key findings For specific objective number 1, we assessed 379 adults, 80% females, median age (IQR) 30 (17-41) years. HIV-1, S. haematobium and S. mansoni prevalence were 26%, 43% and 18% respectively in the MUSH baseline survey. Median (IQR) plasma MBL concentration was 800μg/L (192-1936μg/L). Prevalence of plasma MBL deficiency was 18% with high frequency of the C (codon 57G>A) mutant allele (20%). For specific objective number 2, we found no significant difference in median plasma MBL levels between HIV negative (912μg/L) and HIV positive (688μg/L), p=0.066. However plasma MBL levels at the assay detection limit of 20μg/L were more frequent among the HIV-1 infected (p=0.007). S. haematobium andS. mansoni infected participants had significantly higher MBL levels than uninfected. All MBL2 variants were not associated with HIV-1 infection but promoter variants LY and LL were significantly associated with S. haematobium infection (Paper 1). For specific objective number 3, we assessed 197 HIV positive adults where 83% (164) were women with a median age of 31 years old. Prevalence of plasma MBL deficiency (less than 100μg/L) and MBL2 deficient genetic variants (A/O and O/O genotypes) was 21% (42 out of 197) and 39% (74 out of 190), respectively. We did not observe a significant role to explain individual variation in mortality, change of CD4+ T cell count and viral load by MBL plasma deficiency or MBL2 genetic variants from baseline to 3 years follow up period in this adult population (Paper 2). For specific objective number 4, from the PMTCT study, the median age (IQR) of the mothers was 30(26 - 34) years and the children mean age (IQR) was 12 (11-15) months old at the time of enrolment. All 622 mothers were HIV-1 infected, 574 babies were HIV negative and 48 were HIV-1 positive babies. MBL2 normal structural allele A and variants B (codon 5A>G), C (codon 57 A>G) and promoter region SNPs -550(H/L) and -221(X/Y) were detected. Prevalence of MBL deficiency was 34% among the mothers and 32% among the children. For specific objective number 5, we found no association between maternal MBL2 deficiency and HIV-1 transmission to their children. We found no difference in the distribution of HIV-1 infected and uninfected children between the MBL2 genotypes of the mothers and those of the children (Paper 3). Conclusions The results from our study indicate high prevalence of MBL deficiency but we found no evidence of association between MBL deficiency and HIV-1 infection. However, lower plasma MBL levels were associated with reduced prevalence of both S. haematobium and S. mansoni infections and MBL2 promoter and variants LY and LL were associated with increased susceptibility to S. haematobium infection (Paper 1). Our findings attest to the large between-population variability in a host of factors that can predispose individuals susceptible to HIV progression and mortality. We therefore cannot recommend at this time the use of plasma MBL levels or MBL2 genetic variants as a prognostic marker in HIV infection, disease progression and survival in this adult population in Africa (Paper 2). MBL deficiency was not associated with HIV-1 infection among the children nor was it associated with HIV-1 vertical transmission in this study population (Paper 3). / MT2017

Highly active antiretroviral therapy has successfully limited HIV-1 disease progression to AIDS, but is consistently compromised by the emergence and transmission of HIV-1 drug resistant strains. As a result, a continued search for novel anti-HIV-1 agents with improved pharmacological profiles has become fundamental. Chrysotherapy has been in use since the early 1920s in treatment of rheumatoid arthritis, and has since been investigated for various ailments including HIV/AIDS. This study evaluated 45 synthetic gold compounds for drug like properties using theoretical and experimental techniques with the aim of generating sufficient data to considerably aid the rational design of new anti-HIV agents. Theoretical techniques applied included the Osiris Property Explorer and the Lipinski’s Rule of Five which assessed drug-likeness and bioavailability respectively. In vitro studies included aqueous solubility assays, cytotoxicity (PM1 cell lines and PBMCs) assays, antiviral assays in PBMCs, direct enzyme (RT and IN) inhibition, and the effect of serum protein binding and biological stability on antiviral efficacy. An overall low druglikeness score and an intermediate bioavailability were predicted by the Osiris Molecular Property Explorer. Low drug-likeness was suggested to be due to a high frequency of foreign fragments in the synthetic gold compounds, while their high molecular weight reduced bioavailability. In general gold compounds exhibited cytotoxicity properties and moderate aqueous solubility in vitro. Overall, the 45 synthetic gold compounds did not show activity against HIV-1 replication in vitro. Seven compounds (AB05-AB11) exhibited direct HIV-1 RT inhibition, and compounds AB39 and AB04 demonstrated moderate direct HIV-1 IN inhibition, but this activity was abrogated in PBMC inhibition assays. Serum binding, compound stability and cytotoxicity were all implicated in the lack of HIV-1 inhibition in PBMCs. To this end, data obtained was sufficient to aid in the future rational design of second generation HIV RT and IN inhibitors with acceptable pharmacological properties.

ABSTRACT Incidence estimation and calibration from cross-sectional data of acute infection HIV-1 seroconvertors. May 2007 Eustasius Musenge Masters in Medicine in the Field of Biostatistics and Epidemiology Supervised by: Mr E Marinda and Dr A Welte Background: The HIV-1 incidence (a very important measure used as a proxy for disease burden) can be estimated from a cross-sectional study. This incidence estimate has the advantage of reducing on costs and time, thus enabling more timely intervention; it is also ideal for developing nations. A common procedure used in making this estimate utilizes two antibody tests (Sensitive/Less sensitive tests). Due to the long window period of such tests (at least three months), persons classified as recently infected would have been infected more than three months prior to the test date. Detecting acute HIV-1 infection is very important since this is the most infectious stage of the disease. This research report explores a method of estimating incidence using an antibody test and a virological test, Polymerase Chain Reaction Ribonucleic Acid (PCR-RNA).The cross-sectional data used are from the Centre for the AIDS Programme of Research in South Africa (CAPRISA). Methods: Actual follow-up cohort data from CAPRISA acute infection cohort (AIC), comprised of 245 sex workers, were used to estimate the incidence of HIV-1 using a PCR-RNA ,virology test based, incidence formula. The result obtained was compared to the incidence estimate obtained by the classical method of estimating incidence the AIDS Programme of Research in South Africa (CAPRISA). Methods: Actual follow-up cohort data from CAPRISA acute infection cohort (AIC), comprised of 245 sex workers, were used to estimate the incidence of HIV-1 using a PCR-RNA ,virology test based, incidence formula. The result obtained was compared to the incidence estimate obtained by the classical method of estimating incidence (prospective cohort follow-up). As a measure to reduce costs inherent in virological tests (PCR-RNA), multistage pooling was discussed and several pooling strategies simulations were proposed with their uncertainties. Point estimates and interval estimates of the window period, window period prevalence and incidence from crosssectional study of the AIC cohort were computed. Findings: The mean window period was 6.6 days 95% CI: (2.7 – 13.0). The monthly window period prevalence was 0.09423 percent 95 % CI: (0.0193 – 0.1865)%. The incidence from the prospective cohort follow-up was 5.43 percent 95% CI: (3.9 – 9.2) %. The incidence estimate from cross-sectional formulae was 5.21 percent 95% CI: (4.1– 4.6). It was also shown by use of simulations that an optimum pool sample size is obtained when at least half the samples are removed on every run. Interpretation and recommendations: The PCR-RNA test is very sensitive at detecting acute HIV-1 infected persons. The incidence estimate from the crosssectional study formulae was very similar to that obtained from a follow-up study. The number of tests needed can be reduced and a good estimate of the incidence can still be obtained. The calibration was not accurate since the samples used were small and the window period duration was too short, hence, it was difficult to extrapolate to the whole population. Further work still needs to be done on the calibration of the proposed incidence formulae as it could be a very useful public health tool.

M.Sc. (Med.), Faculty of Health Sciences, University of the Witwatersrand, 2011 / Human Immunodeficiency Virus type 1 (HIV-1) is the causal agent of AIDS, and currently infects 33.3 million individuals worldwide. The gradual depletion of CD4+ T lymphocytes is a characteristic feature of a progressive HIV-1 infection. During HIV-1 infection the number of infected CD4+ T lymphocytes is fewer than the number of CD4+ T lymphocytes that are depleted, therefore suggesting a role for HIV-mediated apoptosis of uninfected bystander CD4+ T lymphocytes. Apoptosis, also known as programmed cell death, is a highly regulated, normal physiological process that results in the disposal of unwanted or corrupted cells such as virally infected cells. Several HIV-1 proteins are involved in HIV-1-mediated apoptosis, of which the envelope (Env) glycoprotein gp120 subunit is the most effective. However, the true mechanism of gp120-mediated apoptosis of uninfected CD4+ T lymphocytes is not fully understood and remains controversial. Furthermore, research focusing on HIV-1 subtype C Env-mediated apoptosis is limited. This study compared the ability of CCR5-utilizing soluble monomeric HIV-1 subtype C gp120 (gp120ZM651), monomeric HIV-1 subtype B gp120 (gp120BaL) and trimeric/oligomeric HIV-1 subtype C gp140 (gp140AncC) to induce apoptosis of uninfected Jurkat T lymphocytes and activated CD4+ T lymphocytes via CD4 and CD4/CCR5 signalling, respectively. All three Env glycoproteins were expressed in HEK 293T cells, purified by lectin affinity chromatography and characterized by assessing their binding capabilities to monoclonal antibodies IgGb12, 17b (in the presence and absence of soluble CD4) and 2G12. Purified recombinant gp120BaL, gp120ZM651 and gp140AncC were found to v be functional and conformationally intact and subsequently added in different concentrations to uninfected Jurkat T lymphocytes and activated CD4+ T lymphocytes. Apoptosis was detected by flow cytometry using Annexin V/7-AAD staining for up to 48 hours post treatment, and further confirmed by TUNEL analysis at 65 hours post treatment. Recombinant gp120BaL, gp120ZM651 and gp140AncC induced low levels of apoptosis in the Jurkat T lymphocytes (6.1%, 5.0% and 6.8%, respectively) and higher levels of apoptosis in the activated CD4+ T lymphocytes (13.3%, 15.6% and 11.5%, respectively) via TUNEL analysis of chromosomal DNA fragmentation. Moreover, comparable levels of apoptosis were observed between the monomeric gp120 and trimeric/oligomeric gp140 forms in both cell types. Interestingly, the subtype C gp140AncC induced higher levels of apoptosis than subtype C gp120ZM651 and subtype B gp120BaL in activated CD4+ T lymphocytes during the Annexin V/7-AAD analysis while the subtype C gp120ZM651 induced higher levels of apoptosis than subtype C gp140AncC and subtype B gp120BaL in activated CD4+ T lymphocytes during the TUNEL analysis. Overall, these results suggest that soluble gp120 is able to mediate low levels of apoptosis via CD4 signalling only in Jurkat T lymphocytes, and these levels are enhanced in activated CD4+ T lymphocytes, possibly due to engagement of gp120 with CD4 and the CCR5 co-receptor on the surface of the target cell.