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The ectodomain of gp41 is the target of potent binding and neutralizing antibodies (NAbs) and is being explored in new strategies for antibody-based HIV vaccines. Previous studies have suggested that the W164A-3S (3S) and EC26-2A4 (EC26) peptides located in the gp41 ectodomain may be potential HIV vaccine candidates. We assessed 3S- and EC26-specific binding antibody responses and related neutralizing activity in a large panel of chronic HIV-1-infected Portuguese individuals on ART. A similar proportion of participants had antibodies binding to 3S (9.6%) and EC26 (9.9%) peptides but the level of reactivity against 3S was significantly higher compared to EC26, except in the rare patients with double peptide reactivity. The higher antigenicity of 3S was unrelated with disease stage, as assessed by CD4+ T cell counts, but it was directly related with plasma viral load. Most patients that were tested (89.9%, N = 268) showed tier 1 neutralizing activity, the potency being inversely associated with plasma viral load. In the subset of patients that were tested for neutralization of tier 2 isolates, neutralization breadth was inversely correlated with plasma viral load and directly correlated with CD4+ T cell counts. These results are consistent with a role for neutralizing antibodies in controlling viral replication and preventing the decline of CD4+ T lymphocytes. Importantly, in patients with 3S-specific antibodies, neutralizing titers were inversely correlated with viral RNA levels and proviral DNA levels. Moreover, patients with 3S and/or EC26-specific antibodies showed a 1.9-fold higher tier 2 neutralization score than patients without antibodies suggesting that 3S and/or EC26-specific antibodies contribute to neutralization breadth and potency in HIV-1 infected patients. Overall, these results suggest that antibodies targeting the S3 and EC26 epitopes may contribute to reduce viral burden and provide further support for the inclusion of 3S and EC26 epitopes in HIV-1 vaccine candidates.

Elicitation of potent neutralizing antibodies against genetically diverse HIV-1 isolates is important for an effective HIV-1 vaccine. Some HIV-1 infected patients produce such broadly neutralizing antibodies (bNAbs). Identification of host and viral correlates of bNAb production may help develop the next generation of HIV-1 vaccines. We carried out the first detailed characterization of the neutralizing antibody response and identify viral and host factors associated with the development of bNAbs in HIV-1 infected patients from Angola, one of the oldest, more dynamic, and diverse HIV-1 epidemics in the world. Plasma samples from 322 HIV-1 infected patients were collected in 2001, 2009 and 2014. Phylogenetic analysis of C2V3C3 envelope sequences identified a diverse array of subtypes including A1, A2, B, C, D, F1, G, H, J, untypable strains, and recombinant forms which prevailed over pure subtypes. Notably, 56% of the patients developed cross, broad, or elite neutralizing responses against a reference panel of tier 2 Env-pseudoviruses far exceeding results obtained elsewhere in the world. The frequency of elite neutralizers was higher in 2014, when patients were on ART and had low viremia, than in 2009 when patients were drug naive. In drug naïve patients, broad neutralization was associated with subtype C infection, lower CD4+ T cell counts, higher age, or higher titer of C2V3C3-specific antibodies relative to patients that did not develop bNAbs. Neutralizing antibodies targeted the V3-glycan supersite in most patients but antibodies specific for the V2 apex, the CD4 binding site, the gp41 membrane-proximal external region (MPER) and unknown epitopes were also found in some patients. V3 and C3 regions were significantly less variable and less subject to positive selection in elite neutralizers compared to weak or no neutralizers suggesting an active role of bNabs directed against these regions in controlling HIV-1 replication and diversification. Hence, development of broad and elite antibody neutralization against HIV-1 requires long-term and low-level envelope V3C3 stimulation from highly diverse subtype C isolates. These results have direct implications for the design of a new generation of HIV-1 vaccines.

In 2015, 257 million people lived with chronic hepatitis B infection. In Portugal 1.4% of the population is chronically infected with hepatitis B virus. Limited information is available regarding the genetic diversity, origin of HBV in Portugal and its role in the dissemination of HBV worldwide. In this study, we aimed to investigate the epidemic history and transmission dynamics of HBV genotypes that are endemic in Portugal. HBV pol gene was sequenced from 130 patients followed in Lisbon. HBV genotype A (HBV/A) was the most prevalent genotype (n=54, 41.5%), followed by D [HBV/D; (n=44, 33.8%)], and E [HBV/E; (n=32, 24.6%)]. Spatio-temporal evolutionary dynamics were reconstructed using a Bayesian Markov Chain Monte Carlo method, as implemented in BEAST v1.10.4, with a GTR nucleotide substitution model, an uncorrelated lognormal relaxed molecular clock model under a Bayesian skyline plot and a continuous diffusion model. Our results indicate that HBV/D4 was the first subgenotype to be introduced in Portugal by the end of the XIX century, around 1857 (HPD 95% 1699 - 1931) followed by subgenotypes D3 and A2 a few decades later. Genotype E and subgenotype A1 were introduced in Portugal later, almost simultaneously. Our results also indicate a very important role of Portugal in the exportation of HBV subgenotypes D4 and A2 to Brazil and Cape Verde, respectively, in the beginning of the XX century. This work clarifies the epidemiological history of HBV in Portugal and show that Portugal had an important role in the global spread of this virus.

Research Areas: Immunology ; Research & Experimental Medicine Development of new immunogens eliciting broadly neutralizing antibodies (bNAbs) is a main priority for the HIV-1 vaccine field. Envelope glycoproteins from non-B-non-C HIV-1clades have not been fully explored as components of a vaccine. We produced Vaccinia viruses expressing a truncated version of gp120 (gp120t) from HIV-1 clades CRF02_AG, H, J, B, and C and examined their immunogenicity in mice and rabbits. Mice primed with the recombinant Vaccinia viruses and boosted with the homologous gp120t or C2V3C3 polypeptides developed antibodies that bind potently to homologous and heterologous envelope glycoproteins. Notably, a subset of mice immunized with the CRF02_AG-based envelope immunogens developed a cross-reactive neutralizing response against tier 2 HIV-1 Env-pseudoviruses and primary isolates. Rabbits vaccinated with the CRF02_AG-based envelope immunogens also generated potent binding antibodies, and one animal elicited antibodies that neutralized almost all (13 of 16, 81.3%) tier 2 HIV-1 isolates tested. Overall, the results suggest that the novel CRF02_AG-based envelope immunogens and prime-boost immunization strategy elicit the type of immune responses required for a preventive HIV-1 vaccine. info:eu-repo/semantics/publishedVersion

Introduction: Characterizing the antibody response, both neutralizing (NAb) and nonneutralizing (nNAb), in HIV-1 infected patients from Portugal may provide useful insights for vaccine design. We make the first detailed characterization of the Nab and nNAb response in Portuguese patients infected with HIV-1 and identify its determinants. Materials and methods: Plasma samples from a total of 403 patients, 372 on ART and 31 drug naïve, were analysed for neutralizing activity against a reference cross-clade Env-pseudotyped tier 2 virus panel (n = 6, subtypes B, C, AC, and CRF07_BC) and one tier one isolate (NL4.3, subtype B) in a single cycle assay in TZM-bl cells. Binding antibody activity to polypeptides comprising the C2V3C3 envelope regions from different HIV-1 clades (CRF02_AG, B, C, G and H) and peptides from a conserved region in gp41 (3S and EC262A4) was evaluated in ELISA assays. Informed consent for blood collection and study participation was obtained from all participants. The study was approved by the Ethical Boards of the Faculty of Medicine, University of Lisbon and Hospital Egas Moniz. Results: Of the 403 plasma samples tested in ELISA assays, 87.7% reacted with at least one polypeptide. The polypeptide from virus CRF02_AG was the most antigenic (61.1%) followed by H (55.1%), B (51.1%), G (50.9%), C (48.9%), 3S (12.9%) and EC262A4 (11.7%). There was a weak but significant positive correlation between the number of peptides recognized and levels of binding antibodies (r = 0.2678, p = 0.0117). Tier 1 (NL4.3) virus was neutralized by most plasma samples [87.9% (188/214) from patients on ART and 77.4% (24/31) from drug naïve patients]. Out of 39 plasma samples tested against the reference tier 2 panel of pseudoviruses, 23 (59.0%) neutralized all viruses (median 83.4% neutralization) and 14 (35.6%) neutralized between 1-5 viruses (median 48.9% neutralization). A positive correlation was observed between neutralizing potency (% of neutralization) and breadth as defined by the number of viruses neutralized (r = 0.7336, p

Submitted by Paula Saraiva (psaraiva@egasmoniz.edu.pt) on 2019-12-12T16:08:44Z No. of bitstreams: 1 Artigo_NTaveira_2019_06_acceptedmanuscript.pdf: 170896 bytes, checksum: a2600eae4891499d563cae74c5262968 (MD5) Approved for entry into archive by Paula Saraiva (psaraiva@egasmoniz.edu.pt) on 2019-12-12T16:08:57Z (GMT) No. of bitstreams: 1 Artigo_NTaveira_2019_06_acceptedmanuscript.pdf: 170896 bytes, checksum: a2600eae4891499d563cae74c5262968 (MD5) Made available in DSpace on 2019-12-12T16:08:57Z (GMT). No. of bitstreams: 1 Artigo_NTaveira_2019_06_acceptedmanuscript.pdf: 170896 bytes, checksum: a2600eae4891499d563cae74c5262968 (MD5) Previous issue date: 2017-11 info:eu-repo/semantics/publishedVersion

BackgroundA vaccine that protects against the different HIV subtypes circulating around the world is essential to control and eliminate HIV infection. The immunogens are the key to develop an effective HIV vaccine. In this study, we characterised the antibody response against recombinant C2V3C3 polypeptides from several HIV-1 subtypes and evaluated the neutralising antibody response.MethodsPlasmas from HIV-1-infected individuals under treatment (n=39) and drugs-naïve individuals (n=8) were tested in an ELISA assay to determine the presence of antibodies against polypeptides from HIV-1 subtypes (CRF02_AG, B, C, G and H). The neutralising activity of plasma was evaluated with a panel of six HIV-1 viruses from a reference panel, [one tier 1 (NL4.3), and five tier 2 (PCH119_CRF07, PCE1176_C, TRO11_B, 246 F3_AC and CRF07_BJOX2000)] in a TZM-bl cells-based assay.ResultsOut of 48 plasmas, 44 (89.6%) reacted at least with one polypeptide and four (10.4%) did not react with any polypeptide. Interestingly, 56% of the plasmas recognise ≥3 peptides and 6 reacted with all polypeptides. The polypeptide from virus CRF02_AG was the most antigenic (77%) followed by the polypeptide C (58.3%), G (58.3%), H (50%) and B (35.4%). There was a positive correlation between polypeptides number recognised and binding antibody reactivity (r=0.4895, p=0.0111). All plasmas from drugs-naïve individuals neutralised at least one virus with neutralising activity between 39.3% and 95.7%. Four plasmas showed neutralising activity >50% against five viruses. The virus 249 F3 was the easiest to neutralise (median, 65.7%), whereas PCH119_CRF07 was the most difficult to neutralise (median, 43.6%). Neutralising activity of plasmas from patients under treatment are ongoing.ConclusionIn summary, these polypeptides could be useful in vaccine design once they are very antigenic and we observed a heterologous neutralising antibody response in naïve patients that expressed positive antibody-response anti-peptides.

Objectives To produce new fusion inhibitor peptides for HIV-1 and HIV-2 based on ancestral envelope sequences. Methods HIV-2/simian immunodeficiency virus (SIV) ancestral transmembrane protein sequences were reconstructed and ancestral peptides were derived from the helical region 2 (HR2). The activity of one ancestral peptide (named P3) was examined against a panel of HIV-1 and HIV-2 primary isolates in TZM-bl cells and peripheral blood mononuclear cells and compared to T-20. Peptide secondary structure was analyzed by circular dichroism. Resistant viruses were selected and resistance mutations were identified by sequencing the env gene. Results P3 has 34 residues and overlaps the N-terminal pocket-binding region and heptad repeat core of HR2. In contrast to T-20, P3 forms a typical α-helical structure in solution, binds strongly to the transmembrane protein, and potently inhibits both HIV-2 (mean IC50, 63.8 nmol/l) and HIV-1 (11 nmol/l) infection, including T-20-resistant isolates. The N43K mutation in the HR1 region of HIV-1 leads to 120-fold resistance to P3 indicating that the HR1 region in transmembrane glycoprotein is the target of P3. No HIV-2-resistant mutations could be selected by P3 suggesting that the genetic barrier to resistance is higher in HIV-2 than in HIV-1. HIV-1-infected patients presented significantly lower P3-specific antibody reactivity compared to T-20. Conclusion P3 is an HIV-2/SIV ancestral peptide with low antigenicity, high stability, and potent activity against both HIV-1, including variants resistant to T-20, and HIV-2. Similar evolutionary biology strategies should be explored to enhance the production of antiviral peptide drugs, microbicides, and vaccines.

Background The baseline susceptibility of primary HIV-2 to maraviroc (MVC) and other entry inhibitors is currently unknown. Methods The susceptibility of 19 HIV-2 isolates obtained from asymptomatic and AIDS patients and seven HIV-1 clinical isolates to the fusion inhibitors enfuvirtide (ENF) and T-1249, and to the coreceptor antagonists AMD3100, TAK-779 and MVC, was measured using a TZM-bl cell-based assay. The 50% inhibitory concentration (IC50), 90% inhibitory concentration (IC90) and dose–response curve slopes were determined for each drug. Results ENF and T-1249 were significantly less active on HIV-2 than on HIV-1 (211- and 2-fold, respectively). AMD3100 and TAK-779 inhibited HIV-2 and HIV-1 CXCR4 tropic (X4) and CCR5 tropic (R5) variants with similar IC50 and IC90 values. MVC, however, inhibited the replication of R5 HIV-2 variants with significantly higher IC90 values (42.7 versus 9.7 nM; P+ T-cells. Conclusions T-1249 is a potent inhibitor of HIV-2 replication indicating that new fusion inhibitors might be useful to treat HIV-2 infection. Coreceptor antagonists TAK-779 and AMD3100 are also potent inhibitors of HIV-2 replication. The reduced sensitivity of R5 variants to MVC, especially in severely immunodeficient patients, indicates that the treatment of HIV-2-infected patients with MVC might require higher dosages than those used in HIV-1 patients, and should be adjusted to the disease stage.

Background Differently from HIV-1, HIV-2 disease progression usually takes decades without antiretroviral therapy and the majority of HIV-2 infected individuals survive as elite controllers with normal CD4+ T cell counts and low or undetectable plasma viral load. Neutralizing antibodies (Nabs) are thought to play a central role in HIV-2 evolution and pathogenesis. However, the dynamic of the Nab response and resulting HIV-2 escape during acute infection and their impact in HIV-2 evolution and disease progression remain largely unknown. Our objective was to characterize the Nab response and the molecular and phenotypic evolution of HIV-2 in association with Nab escape in the first years of infection in two children infected at birth. Results CD4+ T cells decreased from about 50% to below 30% in both children in the first five years of infection and the infecting R5 viruses were replaced by X4 viruses within the same period. With antiretroviral therapy, viral load in child 1 decreased to undetectable levels and CD4+ T cells recovered to normal levels, which have been sustained at least until the age of 12. In contrast, viral load increased in child 2 and she progressed to AIDS and death at age 9. Beginning in the first year of life, child 1 raised high titers of antibodies that neutralized primary R5 isolates more effectively than X4 isolates, both autologous and heterologous. Child 2 raised a weak X4-specific Nab response that decreased sharply as disease progressed. Rate of evolution, nucleotide and amino acid diversity, and positive selection, were significantly higher in the envelope of child 1 compared to child 2. Rates of R5-to-X4 tropism switch, of V1 and V3 sequence diversification, and of convergence of V3 to a β-hairpin structure were related with rate of escape from the neutralizing antibodies. Conclusion Our data suggests that the molecular and phenotypic evolution of the human immunodeficiency virus type 2 envelope are related with the dynamics of the neutralizing antibody response providing further support for a model in which Nabs play an important role in HIV-2 pathogenesis.

This is a non-final version of an article published in final form in AIDS. 28 November 2012 - Volume 26 - Issue 18 - p 2275–2284 Objectives: To characterize the nature and dynamics of the neutralizing antibody (NAb) response and escape in chronically HIV-2 infected patients. Methods: Twenty-eight chronically infected adults were studied over a period of 1-4 years. The neutralizing activity of plasma IgG antibodies against autologous and heterologous primary isolates was analyzed using a standard assay in TZM-bl cells. Coreceptor usage was determined in GHOST cells. The sequence and predicted 3Dstructure of the C2V3C3 Env region were determined for all isolates. Results: Only 50% of the patients consistently produced IgG NAbs to autologous and contemporaneous virus isolates. In contrast, 96% of the patients produced IgG antibodies that neutralized at least two isolates of a panel of six heterologous R5 isolates. Breadth and potency of the neutralizing antibodies were positively associated with the number of CD4+ T cells and with the titer and avidity of C2V3C3-specific binding IgG antibodies. X4 isolates were obtained only from late stage disease patients and were fully resistant to neutralization. The V3 loop of X4 viruses was longer, had a higher net charge and differed markedly in secondary structure compared to R5 viruses. Conclusions: Most HIV-2 patients infected with R5 isolates produce C2V3C3-specific neutralizing antibodies whose potency and breadth decreases as the disease progresses. Resistance to antibody neutralization occurs in late stage disease and is usually associated with X4 viral tropism and major changes in V3 sequence and conformation. Our studies support a model of HIV-2 pathogenesis in which the neutralizing antibodies play a central role and have clear implications for the vaccine field. Fundação para a Ciência e Tecnologia, Portugal

© 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins, Objective: Memory B-cell loss has long been recognized as an important contributor to HIV immunodeficiency. HIV-2 infection, which is characterized by a slow rate of progression to AIDS and reduced to undetectable viremia, provides a unique model to investigate B-cell disturbances. Design and methods: B-cell subsets were evaluated in 38 HIV-2-infected individuals, along with markers of T-cell activation and serum levels of immunoglobulins and a major B-cell homeostatic cytokine, B-cell activating factor (BAFF). Untreated HIV-1-infected and seronegative control individuals were studied in parallel. Statistical analysis was performed using Mann–Whitney tests and Spearman's correlations. Results: We found that HIV-2 was associated with significant depletion of both unswitched (CD27+IgD+) and switched (CD27+IgDneg) memory B-cells that directly correlated with T-cell activation, even in individuals with undetectable plasma viral load. Nevertheless, the presence of detectable viremia, even at low levels, was associated with significant memory B-cell loss and higher BAFF levels. Moreover, these alterations were not recovered by antiretroviral-therapy, as treated HIV-2-infected patients showed more pronounced B-cell disturbances, possibly related to their extended length of infection. Conclusion: These first data regarding B-cell imbalances during HIV-2 infection show that, irrespective of viremia, prolonged HIV infection leads to irreversible damage of memory B-cell homeostasis., This work was supported by grant (PIC/IC/82712/2007) from ‘Fundação para a Ciência e a Tecnologia’ (FCT) and by ‘Programa Operacional Ciência e Inovação 2010’ (POCI2010), as well as by Fundaçao Calouste Gulbenkian to AES. RT, RBF, RSS, and RC received scholarships from FCT.

Human immunodeficiency virus type 2 (HIV-2) infection affects about 1 to 2 million individuals, the majority living in West Africa, Europe, and India. As for HIV-1, new strategies for the prevention of HIV-2 infection are needed. Our aim was to produce new vaccine immunogens that elicit the production of broadly reactive HIV-2 neutralizing antibodies (NAbs). Native and truncated envelope proteins from the reference HIV-2ALI isolate were expressed in vaccinia virus or in bacteria. This source isolate was used due to its unique phenotype combining CD4 independence and CCR5 usage. NAbs were not elicited in BALB/c mice by single immunization with a truncated and fully glycosylated envelope gp125 (gp125t) or a recombinant polypeptide comprising the C2, V3, and C3 envelope regions (rpC2-C3). A strong and broad NAb response was, however, elicited in mice primed with gp125t expressed in vaccinia virus and boosted with rpC2-C3. Serum from these animals potently neutralized (median 50% neutralizing titer, 3,200) six of six highly divergent primary HIV-2 isolates. Coreceptor usage and the V3 sequence of NAb-sensitive isolates were similar to that of the vaccinating immunogen (HIV-2ALI). In contrast, NAbs were not reactive on three X4 isolates that displayed major changes in V3 loop sequence and structure. Collectively, our findings demonstrate that broadly reactive HIV-2 NAbs can be elicited by using a vaccinia virus vector-prime/rpC2-C3-boost immunization strategy and suggest a potential relationship between escape to neutralization and cell tropism.

The objective of this study was to estimate and compare the evolutionary rates of HIV-2 and HIV-1. Two HIV-2 data sets from patients with advanced disease were compared to matched HIV-1 data sets. The estimated mean evolutionary rate of HIV-2 was significantly higher than the estimated rate of HIV-1, both in the gp125 and in the V3 region of the env gene. In addition, the rate of synonymous substitutions in gp125 was significantly higher for HIV-2 than for HIV-1, possibly indicating a shorter generation time or higher mutation rate of HIV-2. Thus, the lower virulence of HIV-2 does not appear to translate into a lower rate of evolution.

Objective: To examine the unspecific and envelope-specific IgA and IgG responses in acute and chronic HIV-2 infection. Methods: Twenty-eight chronically infected adults and two children with perinatal infection were studied. Total plasma concentrations of IgA and IgG were determined by nephelometry. IgA and IgG reactivity against the immunodominant region in gp36 and the C2V3C3 region in gp125 was tested with the enzyme-linked immunosorbent assay (ELISA)‐HIV-2 assay. Clonal sequences of the C2V3C3 env region were obtained for most patients. Results: Total plasma IgG concentration, but not IgA, was significantly higher than normal in HIV-2 patients and correlated inversely with CD4 þ T-cell counts. Seroconversion to gp36 occurred during thefirst year of life in both infants. The infant with rapid disease progression did not elicit C2V3C3-specific antibodies. Most chronically infected patients produced plasma IgG1, IgG3 and IgA antibodies against gp36 and C2V3C3. Lack of C2V3C3-specific IgG response in two patients was associated with a majorantigenic changein the V3 region.In longitudinalanalysis, there was a significant inverse association between the C2V3C3-specific IgG antibody response and the number of CD4 þ T cells. Conclusion: HIV-2promotesanearly,strongandbroadgp36andC2V3C3-specificIgG and IgA response. Increase in the IgG response against the envelope C2V3C3 region is associated with increased loss of CD4 þ T cells in chronically infected patients. These results provide further support for the immune protective role of the C2V3C3 envelope region during HIV-2 infection and have direct implications for HIV-2 diagnosis, clinical management and pathogenesis. 2008 Wolters Kluwer Health | Lippincott Williams & Wilkins AIDS 2008, 22:2257‐2265

BackgroundThis study was designed to investigate, for the first time, the short-term molecular evolution of the HIV-2 C2, V3 and C3 envelope regions and its association with the immune response. Clonal sequences of theenvC2V3C3 region were obtained from a cohort of eighteen HIV-2 chronically infected patients followed prospectively during 2–4 years. Genetic diversity, divergence, positive selection and glycosylation in the C2V3C3 region were analysed as a function of the number of CD4+ T cells and the anti-C2V3C3 IgG and IgA antibody reactivityResultsThe mean intra-host nucleotide diversity was 2.1% (SD, 1.1%), increasing along the course of infection in most patients. Diversity at the amino acid level was significantly lower for the V3 region and higher for the C2 region. The average divergence rate was 0.014 substitutions/site/year, which is similar to that reported in chronic HIV-1 infection. The number and position of positively selected sites was highly variable, except for codons 267 and 270 in C2 that were under strong and persistent positive selection in most patients. N-glycosylation sites located in C2 and V3 were conserved in all patients along the course of infection. Intra-host variation of C2V3C3-specific IgG response over time was inversely associated with the variation in nucleotide and amino acid diversity of the C2V3C3 region. Variation of the C2V3C3-specific IgA response was inversely associated with variation in the number of N-glycosylation sites.ConclusionThe evolutionary dynamics of HIV-2 envelope during chronic aviremic infection is similar to HIV-1 implying that the virus should be actively replicating in cellular compartments. Convergent evolution of N-glycosylation in C2 and V3, and the limited diversification of V3, indicates that there are important functional constraints to the potential diversity of the HIV-2 envelope. C2V3C3-specific IgG antibodies are effective at reducing viral population size limiting the number of virus escape mutants. The C3 region seems to be a target for IgA antibodies and increasing N-linked glycosylation may prevent HIV-2 envelope recognition by these antibodies. Our results provide new insights into the biology of HIV-2 and its relation with the human host and may have important implications for vaccine design.

A dual-antigen enzyme-linked immunosorbent assay specific for human immunodeficiency virus type 2 (HIV-2) envelope proteins, ELISA-HIV2, was developed with two new recombinant polypeptides, rpC2-C3 and rgp36, derived from the HIV-2 envelope. The diagnostic performance was determined with HIV-2, HIV-1, and HIV-1/2 samples. Both polypeptides showed 100% specificity. Clinical sensitivity was 100% for rgp36 and 93.4% for rpC2-C3. ELISA-HIV2 may be used for the specific diagnosis and confirmation of HIV-2 infection.

One anticapsid (p26) mouse monoclonal antibody was developed after immunization with recombinant p26 Gag protein and was tested for reactivity with different HIV-1 and HIV-2 isolates by ELISA and Western blot analysis. This antibody, named R26.1, reacted with all HIV-2 isolates tested and with recombinant p26 proteins, but no HIV-1 isolates. The epitope of antibody R26.1 was mapped to residues 50-71 in the N-terminal domain of the capsid protein, a highly conserved region in all HIV-2 isolates sequenced to date. This monoclonal antibody may be useful for the detection of HIV-2, and for the discrimination between HIV-1 and HIV-2 infections. Likewise, the identified epitope may be useful for the detection of p26 antibodies in HIV-2-infected individuals.

Tese de doutoramento, Ciências Biomédicas (Ciências Biopatalógicas), Universidade de Lisboa, Faculdade de Medicina, 2011 Submitted by Marta Nogueira (mnogueira@reitoria.ul.pt) on 2011-07-20T14:22:23Z No. of bitstreams: 1 ulsd060913_td_José_Marcelino.pdf: 4272276 bytes, checksum: b662c7566e8bb4b8c9f0646f28ca4d20 (MD5) Made available in DSpace on 2011-07-20T14:22:32Z (GMT). No. of bitstreams: 1 ulsd060913_td_José_Marcelino.pdf: 4272276 bytes, checksum: b662c7566e8bb4b8c9f0646f28ca4d20 (MD5) Previous issue date: 2011 Fundação para a Ciência e a Tecnologia (FCT, POCTI/ESP/48045/2002; Bolsa de Doutoramento SFRH/BD/13892/2003)