Browsing by Author "Taveira, Nuno"
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- Accidental father-to-son HIV-1 transmission during the seroconversion periodPublication . Ezeonwumelu, Ifeanyi; Bártolo, Inês; Martin, Francisco; Abecasis, Ana; Campos, Teresa; Romero-Severson, Ethan O.; Leitner, Thomas; Taveira, NunoA 4-year-old child born to an HIV-1 seronegative mother was diagnosed with HIV-1, the main risk factor being transmission from the child's father who was seroconverting at the time of the child's birth. In the context of a forensic investigation, we aimed to identify the source of infection of the child and date of the transmission event. Samples were collected from the father and child at two time points about 4 years after the child's birth. Partial segments of three HIV-1 genes (gag, pol, and env) were sequenced and maximum likelihood (ML) and Bayesian methods were used to determine direction and estimate date of transmission. Neutralizing antibodies were determined using a single cycle assay. Bayesian trees displayed a paraphyletic–monophyletic topology in all three genomic regions, with the father's host label at the root, which is consistent with father-to-son transmission. ML trees found similar topologies in gag and pol and a monophyletic–monophyletic topology in env. Analysis of the time of the most recent common ancestor of each HIV-1 gene population indicated that the child was infected shortly after the father. Consistent with the infection history, both father and son developed broad and potent HIV-specific neutralizing antibody responses. In conclusion, the direction of transmission implicated the father as the source of transmission. Transmission occurred during the seroconversion period when the father was unaware of the infection and was likely accidental. This case shows how genetic, phylogenetic, and serological data can contribute for the forensic investigation of HIV transmission.
- An ancestral HIV-2/simian immunodeficiency virus peptide with potent HIV-1 and HIV-2 fusion inhibitor activityPublication . Borrego, Pedro; Calado, Rita; Marcelino, José M.; Pereira, Patrícia; Quintas, Alexandre; Barroso, Helena; Taveira, Nuno"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 a-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."
- Antagonism of BST-2/Tetherin is a conserved function of the Env glycoprotein of primary HIV-2 isolatesPublication . Chen, Chia-Yen; Shingai, Masashi; Welbourn, Sarah; Martin, Malcolm A.; Borrego, Pedro; Taveira, Nuno; Strebel, KlausAlthough HIV-2 does not encode a vpu gene, the ability to antagonize bone marrow stromal antigen 2 (BST-2) is conserved in some HIV-2 isolates, where it is controlled by the Env glycoprotein. We previously reported that a single-amino-acid difference between the laboratory-adapted ROD10 and ROD14 Envs controlled the enhancement of virus release (referred to here as Vpu-like) activity. Here, we investigated how conserved the Vpu-like activity is in primary HIV-2 isolates. We found that half of the 34 tested primary HIV-2 Env isolates obtained from 7 different patients enhanced virus release. Interestingly, most HIV-2 patients harbored a mixed population of viruses containing or lacking Vpu-like activity. Vpu-like activity and Envelope functionality varied significantly among Env isolates; however, there was no direct correlation between these two functions, suggesting they evolved independently. In comparing the Env sequences from one HIV-2 patient, we found that similar to the ROD10/ROD14 Envs, a single-amino-acid change (T568I) in the ectodomain of the TM subunit was sufficient to confer Vpu-like activity to an inactive Env variant. Surprisingly, however, absence of Vpu-like activity was not correlated with absence of BST-2 interaction. Taken together, our data suggest that maintaining the ability to antagonize BST-2 is of functional relevance not only to HIV-1 but also to HIV-2 as well. Our data show that as with Vpu, binding of HIV-2 Env to BST-2 is important but not sufficient for antagonism. Finally, as observed previously, the Vpu-like activity in HIV-2 Env can be controlled by single-residue changes in the TM subunit.
- Assessment of the Cavidi ExaVir load assay for monitoring plasma viral load in HIV-2-infected patientsPublication . Borrego, Pedro; Gonçalves, Maria Fátima; Gomes, Perpétua; Araújo, Lavínia; Moranguinho, Inês; Figueiredo, Inês Brito; Barahona, Isabel; Rocha, José; Mendonça, Claudino; Cruz, Maria Cesarina; Barreto, Jorge; Taveira, NunoHIV plasma viral load is an established marker of disease progression and of response to antiretroviral therapy, but currently there is no commercial assay validated for the quantification of viral load in HIV-2-infected individuals. We sought to make the first clinical evaluation of Cavidi ExaVir Load (version 3) in HIV-2- infected patients. Samples were collected from a total of 102 individuals living in Cape Verde, and the HIV-2 viral load was quantified by both ExaVir Load and a reference in-house real-time quantitative PCR (qPCR) used in Portugal in 91 samples. The associations between viral load and clinical prognostic variables (CD4 T cell counts and antiretroviral therapy status) were similar for measurements obtained using ExaVir Load and qPCR. There was no difference between the two methods in the capacity to discriminate between nonquantifiable and quantifiable HIV-2 in the plasma. In samples with an HIV-2 viral load quantifiable by both methods (n 27), the measurements were highly correlated (Pearson r 0.908), but the ExaVir Load values were systematically higher relative to those determined by qPCR (median difference, 0.942 log10 copies/ml). A regression model was derived that enables the conversion of ExaVir Load results to those that would have been obtained by the reference qPCR. In conclusion, ExaVir Load version 3 is a reliable commercial assay to measure viral load in HIV-2-infected patients and therefore a valuable alternative to the inhouse assays in current use.
- Bacteriophage isolation from human saliva: a pilot study with high school studentsPublication . Nascimento, Teresa; Marvão, Matilde; Bugalho, Joana; Bastos, Marta; Luz, Andreia; Maurício, Paulo; Taveira, Nuno
- Baseline susceptibility of primary HIV-2 to entry inhibitorsPublication . Borrego, Pedro; Calado, Rita; Marcelino, José M; Bártolo, Inês; Rocha, Cheila; Cavaco-Silva, Patrícia; Doroana, Manuela; Antunes, Francisco; Maltez, Fernando; Caixas, Umbelina; Barroso, Helena; Taveira, NunoBackground: The baseline susceptibility of primary HIV-2 to maraviroc (MVC) and other entry inhibitors is currently unknown.
- Determinants of highly active antiretroviral therapy duration in HIV-1-infected children and adolescents in Madrid, Spain, from 1996 to 2012Publication . Palladino, Claudia; Briz, Verónica; Bellón, José María; Climent, Francisco J.; De Ory, Santiago J.; Mellado, María José; Navarro, María Luisa; Ramos, José T.; Taveira, Nuno; De José, María Isabel; Munõz-Fernandes, María Ángeles; CoRISpeS-Madrid Cohort Working Group"Objectives: To investigate the duration of sequential HAART regimens and predictors of first-line regimen discontinuation among HIV-1 vertically infected children and adolescents. Design: Multicentre survey of antiretroviral-naı¨ve patients enrolled in the HIV-Paediatric Cohor,t CoRISpeS-Madrid Cohort, Spain. Methods: Patients with a follow-up of $1 month spent on HAART, with available baseline CD4 count and HIV-viral load (VL) were included. Time spent on sequential HAART regimens was estimated and multivariable regression was used to identify predictors of time to first-line regimen discontinuation. Results: 104 patients were followed for a median 8 years after starting HAART among 1996–2012; baseline %CD4 was 21.5 (12.3–34.0)and viral load was 5.1 (4.6–5.6) log10 copies/mL. Patients received a mean of 1.9 regimens. Median time on firstline HAART (n = 104) was 64.5 months; second HAART (n = 56) 69.8 months; and third HAART (n = 21) 66.5 months. Eleven (11%) patients were lost to follow-up while on first-line HAART and 54% discontinued (cumulative incidence of 16% and 38% by 1 and 3-year, respectively). The main predictor of first-line regimen discontinuation was suboptimal adherence to antiretrovirals (AHR: 2.60; 95% CI: 1.44–4.70). Conclusions: Adherence to therapy was the main determinant of the duration of the first-line HAART regimen in children. It is important to identify patients at high risk for non-adherence, such as very young children and adolescents, in provide special care and support to those patients."
- Development of synthetic light-chain antibodies as novel and potent HIV fusion inhibitorsPublication . Cunha-Santos, Catarina; Figueira, Tiago N.; Borrego, Pedro; Oliveira, Soraia S.; Rocha, Cheila; Couto, Andreia; Cantante, Cátia; Santos- Costa, Quirina; Azevedo-Pereira, José M.; Fontes, Carlos M. G. A.; Taveira, Nuno; Aires-Da-Silva, Frederico; Castanho, Miguel A. R. B.; Veiga, Ana Salomé; Gonçalves, João"Objective: To develop a novel and potent fusion inhibitor of HIV infection based on a rational strategy for synthetic antibody library construction. Design: The reduced molecular weight of single-domain antibodies (sdAbs) allows targeting of cryptic epitopes, the most conserved and critical ones in the context of HIV entry. Heavy-chain sdAbs from camelids are particularly suited for this type of epitope recognition because of the presence of long and flexible antigen-binding regions [complementary-determining regions (CDRs)]."
- Development of water-soluble polyanionic carbosilane dendrimers as novel and highly potent topical anti-HIV-2 microbicidesPublication . Briz, Verónica; Sepúlveda-Crespo, Daniel; Diniz, Ana Rita; Borrego, Pedro; Rodes, Berta; Javier de la Mata, Francisco; Gómez, Rafael; Taveira, Nuno; Muñoz-Fernández, Mª Ángeles"The development of topical microbicide formulations for vaginal delivery to prevent HIV-2 sexual transmission is urgently needed. Second- and third-generation polyanionic carbosilane dendrimers with a silicon atom core and 16 sulfonate (G2-S16), napthylsulfonate (G2-NS16) and sulphate (G3-Sh16) end-groups have shown potent and broad-spectrum anti-HIV-1 activity. However, their antiviral activity against HIV-2 and mode of action have not been probed. Cytotoxicity, anti-HIV-2, anti-sperm and antimicrobial activities of dendrimers were determined. Analysis of combined effects of triple combinations with tenofovir and raltegravir was performed by using CalcuSyn software. We also assessed the mode of antiviral action on the inhibition of HIV-2 infection through a panel of different in vitro antiviral assays: attachment, internalization in PBMCs, inactivation and cell-based fusion. Vaginal irritation and histological analysis in female BALB/c mice were evaluated. Our results suggest that G2-S16, G2-NS16 and G3-Sh16 exert anti-HIV-2 activity at an early stage of viral replication inactivating the virus, inhibiting cell-to-cell HIV-2 transmission, and blocking the binding of gp120 to CD4, and the HIV-2 entry. Triple combinations with tenofovir and raltegravir increased the anti-HIV-2 activity, consistent with synergistic interactions (CIwt: 0.33–0.66). No vaginal irritation was detected in BALB/c mice after two consecutive applications for 2 days with 3% G2-S16. Our results have clearly shown that G2-S16, G2-NS16 and G3-Sh16 have high potency against HIV-2 infection. The modes of action confirm their multifactorial and non-specific ability, suggesting that these dendrimers deserve further studies as potential candidate microbicides to prevent vaginal/rectal HIV-1/HIV-2 transmission in humans."
- Donor-Recipient identification in para- and poly-phyletic trees under alternative HIV-1 transmission hypotheses using approximate Bayesian computationPublication . Romero-Severson, Ethan O.; Bulla, Ingo; Hengartner, Nick; Bártolo, Inês; Abecasis, Ana; Azevedo-Pereira, José M.; Taveira, Nuno; Leitner, ThomasDiversity of the founding population of Human Immunodeficiency Virus Type 1 (HIV-1) transmissions raises many important biological, clinical, and epidemiological issues. In up to 40% of sexual infections, there is clear evidence for multiple founding variants, which can influence the efficacy of putative prevention methods, and the reconstruction of epidemiologic histories. To infer who-infected-whom, and to compute the probability of alternative transmission scenarios while explicitly taking phylogenetic uncertainty into account, we created an approximate Bayesian computation (ABC) method based on a set of statistics measuring phylogenetic topology, branch lengths, and genetic diversity. We applied our method to a suspected heterosexual transmission case involving three individuals, showing a complex monophyletic-paraphyletic-polyphyletic phylogenetic topology. We detected that seven phylogenetic lineages had been transmitted between two of the individuals based on the available samples, implying that many more unsampled lineages had also been transmitted. Testing whether the lineages had been transmitted at one time or over some length of time suggested that an ongoing superinfection process over several years was most likely. While one individual was found unlinked to the other two, surprisingly, when evaluating two competing epidemiological priors, the donor of the two that did infect each other was not identified by the host root-label, and was also not the primary suspect in that transmission. This highlights that it is important to take epidemiological information into account when analyzing support for one transmission hypothesis over another, as results may be nonintuitive and sensitive to details about sampling dates relative to possible infection dates. Our study provides a formal inference framework to include information on infection and sampling times, and to investigate ancestral node-label states, transmission direction, transmitted genetic diversity, and frequency of transmission.