Detection and Characterisation of SARS-CoV-2 in Eastern Province of Zambia: A Retrospective Genomic Surveillance Study.

Mutations have driven the evolution and development of new variants of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with potential implications for increased transmissibility, disease severity and vaccine escape among others. Genome sequencing is a technique that allows scientists to read the genetic code of an organism and has become a powerful tool for studying emerging infectious diseases. Here, we conducted a cross-sectional study in selected districts of the Eastern Province of Zambia, from November 2021 to February 2022. We analyzed SARS-CoV-2 samples (n = 76) using high-throughput sequencing. A total of 4097 mutations were identified in 69 SARS-CoV-2 genomes with 47% (1925/4097) of the mutations occurring in the spike protein. We identified 83 unique amino acid mutations in the spike protein of the seven Omicron sublineages (BA.1, BA.1.1, BA.1.14, BA.1.18, BA.1.21, BA.2, BA.2.23 and XT). Of these, 43.4% (36/83) were present in the receptor binding domain, while 14.5% (12/83) were in the receptor binding motif. While we identified a potential recombinant XT strain, the highly transmissible BA.2 sublineage was more predominant (40.8%). We observed the substitution of other variants with the Omicron strain in the Eastern Province. This work shows the importance of pandemic preparedness and the need to monitor disease in the general population.

Identification of Acute HIV-1 Infection by Hologic Aptima HIV-1 RNA Qualitative Assay.

The Hologic Aptima HIV-1 Qualitative RNA assay was used in a rigorous screening approach designed to identify individuals at the earliest stage of HIV-1 infection for enrollment into subsequent studies of cellular and viral events in early infection (RV 217/Early Capture HIV Cohort [ECHO] study). Volunteers at high risk for HIV-1 infection were recruited from study sites in Thailand, Tanzania, Uganda, and Kenya with high HIV-1 prevalence rates among the populations examined. Small-volume blood samples were collected by finger stick at twice-weekly intervals and tested with the Aptima assay. Participants with reactive Aptima test results were contacted immediately for entry into a more comprehensive follow-up schedule with frequent blood draws. Evaluation of the Aptima test prior to use in this study showed a detection sensitivity of 5.5 copies/ml (50%), with all major HIV-1 subtypes detected. A total of 54,306 specimens from 1,112 volunteers were examined during the initial study period (August 2009 to November 2010); 27 individuals were identified as converting from uninfected to infected status. A sporadic reactive Aptima signal was observed in HIV-1-infected individuals under antiretroviral therapy. Occasional false-reactive Aptima results in uninfected individuals, or nonreactive results in HIV-1-infected individuals not on therapy, were observed and used to calculate assay sensitivity and specificity. The sensitivity and specificity of the Aptima assay were 99.03% and 99.23%, respectively; positive and negative predictive values were 92.01% and 99.91%, respectively. Conversion from HIV-1-uninfected to -infected status was rapid, with no evidence of a prolonged period of intermittent low-level viremia.

Etiology and antimicrobial susceptibility of pathogens responsible for urethral discharge among men in Harare, Zimbabwe.

BACKGROUND: Periodic etiological surveillance of sexually transmitted infection (STI) syndromes is required to validate treatment algorithms used to control STIs. However, such surveys have not been performed in Zimbabwe over the past decade. METHODS: A cross-sectional study design was used to determine the prevalence of the key STI etiological agents causing male urethral discharge (MUD). Urethral swab specimens were collected for molecular analysis and Neisseria gonorrhoeae isolation from consenting men 18 years and older who presented with MUD to the 12 clinics in Harare, Zimbabwe, between November 2010 and May 2011. A validated in-house multiplex polymerase chain reaction assay was used to detect the presence of N. gonorrhoeae, Chlamydia trachomatis, Trichomonas vaginalis, and Mycoplasma genitalium. Gonococci were cultured on selective media, and antimicrobial susceptibilities were determined locally for ciprofloxacin, kanamycin, ceftriaxone, and cefixime using Etest strips, and minimum inhibitory concentrations were reported using defined breakpoints. RESULTS: Among 130 participants, N. gonorrhoeae was the most frequent pathogen detected (106; 82.8%), followed by C. trachomatis (15; 11.7%), M. genitalium (6; 4.7%), and T. vaginalis (2; 1.6%). Four (6.1%) of the 66 gonococci isolated were resistant to fluoroquinolones, whereas all viable isolates were susceptible to kanamycin, cefixime, and ceftriaxone. CONCLUSIONS: Gonorrhea is the most important cause of MUD in men in Harare, and our study highlights the emergence of fluoroquinolone-resistant N. gonorrhoeae. Further STI surveys are required in other regions of Zimbabwe to obtain a nationally representative picture of gonococcal burden and antimicrobial resistance among MUD patients.

An Integrated Sample Referral System for HIV Viral Load and Early Infant Diagnosis in North-Western Province, Zambia-A Retrospective Cross-Sectional Study.

Zambia's adult HIV prevalence is high at 11% and faces challenges in achieving UNAIDS 95-95-95 targets for HIV, with a national viral load suppression of 86.2% falling short of the required 95%. North-Western Province has the lowest viral load suppression at 77.5%. Our study investigated the role of an integrated sample referral system in optimizing HIV viral load coverage and Early Infant Diagnosis turnaround time in the province. Using electronic data from the DISA Laboratory Information System and Smartcare, a retrospective cross-sectional analysis was conducted, involving 160,922 viral load and Early Infant Diagnosis results. The chi-square test and multiple linear regression were used for analysis. Following the implementation of the integrated sample referral system, viral load coverage consistently increased monthly (p < 0.001), Early Infant Diagnosis turnaround time improved by 47.7%, and sample volume increased by 25%. The study identifies associations between various factors and testing outcomes. These findings demonstrate improvements in viral load coverage and the Early Infant Diagnosis turnaround time and suggest targeting modifiable factors to further optimize the referral system. We recommend continued strengthening of the referral system and more deliberate demand-creation implementation strategies.

Heterologous cAd3-Ebola and MVA-EbolaZ vaccines are safe and immunogenic in US and Uganda phase 1/1b trials.

Ebola virus disease (EVD) is a filoviral infection caused by virus species of the Ebolavirus genus including Zaire ebolavirus (EBOV) and Sudan ebolavirus (SUDV). We investigated the safety and immunogenicity of a heterologous prime-boost regimen involving a chimpanzee adenovirus 3 vectored Ebola vaccine [either monovalent (cAd3-EBOZ) or bivalent (cAd3-EBO)] prime followed by a recombinant modified vaccinia virus Ankara EBOV vaccine (MVA-EbolaZ) boost in two phase 1/1b randomized open-label clinical trials in healthy adults in the United States (US) and Uganda (UG). Trial US (NCT02408913) enrolled 140 participants, including 26 EVD vaccine-naïve and 114 cAd3-Ebola-experienced participants (April-November 2015). Trial UG (NCT02354404) enrolled 90 participants, including 60 EVD vaccine-naïve and 30 DNA Ebola vaccine-experienced participants (February-April 2015). All tested vaccines and regimens were safe and well tolerated with no serious adverse events reported related to study products. Solicited local and systemic reactogenicity was mostly mild to moderate in severity. The heterologous prime-boost regimen was immunogenic, including induction of durable antibody responses which peaked as early as two weeks and persisted up to one year after each vaccination. Different prime-boost intervals impacted the magnitude of humoral and cellular immune responses. The results from these studies demonstrate promising implications for use of these vaccines in both prophylactic and outbreak settings.

In-vitro Immunomodulatory activity of Azadirachta indica A.Juss. Ethanol: water mixture against HIV associated chronic CD4+ T-cell activation/ exhaustion.

BACKGROUND: In Sub-Saharan Africa, herbal therapy continues to be utilized for HIV-1 disease management. However, the therapeutic benefits of these substances remain ambiguous. To date, little is known about the effects of these plant extracts on chronic CD4 + T-cell activation and exhaustion which is partly driven by HIV-1 associated microbial translocation. METHODS: Effects of Azadirachta indica, Momordica foetida and Moringa oleifera ethanol: water mixtures on cell viability were evaluated using the Guava PCA system. Then, an in-vitro cell culture model was developed to mimic CD4+ T cell exposures to antigens following HIV-1 microbial translocation. In this, peripheral blood mononuclear cells (PBMCs) isolated from HIV negative (n = 13), viral load < 1000 copies per mL (n = 10) and viral load > 1000 copies per mL (n = 6) study participants from rural Uganda were treated with Staphylococcus enterotoxin B (SEB). Then, the candidate plant extract (A. indica) was added to test the potential to inhibit corresponding CD4+ T cell activation. Following BD Facs Canto II event acquisition, variations in %CD38, %CD69, Human Leukocyte Antigen -DR (HLA-DR), Programmed cell death protein 1 (PD-1), T-cell immunoglobulin and mucin domain-containing protein 3 (Tim-3), interferon gamma (IFN γ) and interleukin 2 (IL-2) CD4 + T cell expression were evaluated. RESULTS: Following exposure to SEB, only A. indica demonstrated a concentration-dependent ability to downregulate the levels of CD4 + T cell activation. At the final concentration of 0.500 µg/mL of A. indica, a significant downregulation of CD4 + CD38 + HLA-DR+ expression was observed in HIV negative (p < 0.0001) and both HIV infected groups (P = 0.0313). This plant extract also significantly lowered SEB induced % CD4+ T cell HLADR, PD-1 and Tim-3 levels. PD-1 and CD69 markers were only significantly downmodulated in only the HIV negative ((p = 0.0001 and p = 0.0078 respectively) and viral load< 1000 copies per ml (p = 0.0078) groups. CONCLUSION: A. indica exhibited the in-vitro immunomodulatory potential to inhibit the continuum of SEB induced CD4+ T-cell activation/ exhaustion without impacting general T-cell specific functions such as cytokine secretion. Additional studies are needed to confirm A. indica as a source of natural products for targeting persistent immune activation and inflammation during ART.

Tenofovir resistance in early and long-term treated patients on first-line antiretroviral therapy in eight low-income and middle-income countries.

OBJECTIVE: We aimed to assess the frequency of tenofovir (TDF) resistance in people failing tenofovir/lamivudine or emtricitabine (XTC)/nonnucleotide reverse-transcriptase inhibitor-based first-line antiretroviral treatment (ART) using data from 15 nationally representative surveys of HIV drug resistance conducted between 2014 and 2018 in Cameroon, Guatemala, Honduras, Nicaragua, Senegal, Uganda, Vietnam and Zambia. METHODS: Prevalence of nucleoside reverse-transcriptase inhibitor resistance among participants with virological nonsuppression (viral load ≥1000 copies/ml) who had received TDF-based ART for 12-24 months (early ART group) and at least 40 months (long-term ART group) was assessed using Sanger sequencing and resistance was interpreted using the Stanford HIVdb algorithm. For each group, we estimated a pooled prevalence using random effect meta-analysis. RESULTS: Of 4677 participants enrolled in the surveys, 640 (13.7%) had virological nonsuppression, 431 (67.3%) were successfully genotyped and were included in the analysis; of those, 60.3% (260) were participants in the early ART group. Overall, 39.1, 57.9, 38.5 and 3.6% patients in the early ART group and 42.9, 69.3, 42.9 and 10.0% patients on long-term ART had resistance to TDF, XTC, TDF + XTC and TDF + XTC + zidovudine, respectively. Overall, tenofovir resistance was mainly due to K65R or K70E/G/N/A/S/T/Y115F mutations (79%) but also due to thymidine analogue mutations (21%) which arise from exposure to thymidine analogues but causing cross-resistance to TDF. CONCLUSION: Dual resistance to TDF + XTC occurred in more than 40% of the people with viral nonsuppression receiving tenofovir-based first-line ART, supporting WHO recommendation to optimize the nucleoside backbone in second-line treatment and cautioning against single drug substitutions in people with unsuppressed viral load.

First case of Dolutegravir and Darunavir/r multi drug-resistant HIV-1 in Cameroon following exposure to Raltegravir: lessons and implications in the era of transition to Dolutegravir-based regimens.

BACKGROUND: Sub-Saharan African countries are transitioning to dolutegravir-based regimens, even for patients with extensive previous drug exposure, including first-generation integrase strand-transfer inhibitors (INSTI) such as raltegravir. Such exposure might have implications on cross-resistance to dolutegravir-based antiretroviral therapies (ART). CASE PRESENTATION: We report a 65 years old Cameroonian, previously exposed to raltegravir, and failing on third-line treatment with multi-drug resistance to darunavir/r and dolutegravir. Genotypic resistance testing (GRT) and viral tropism were performed during monitoring time points. The patient initiated ART in August 2007. At the time point of the first (29.04.2010), second (01.12.2017) and third (08.08.2019) GRT, prior ART exposure included 3TC, d4T, NVP and EFV; additionally TDF, DRV/r and RAL; and additionally ABC and DTG respectively. First GRT revealed mutations associated with resistance only to first-generation Non-nucleoside reverse transcriptase inhibitors (NNRTI). Second GRT revealed mutations associated with high-level resistance to all NRTIs, first generation NNRTIs, all ritonavir boosted protease inhibitors (PI/r), and all INSTI, while viral tropism (using geno2pheno) revealed a CCR5-tropic virus with a false positive rate (FPR) of 60.9% suggesting effectiveness of maraviroc (MRV). The third GRT showed high-level resistance to NRTI, NNRTI, all PI and all INSTI, with additional mutations (H221HY for NNRTI and S147G for INSTI), and a CCR5-tropic virus with a slightly reduced FPR (57.0%). Without any locally available active therapeutic option, the patient has been on a maintenance therapy with "DRV/r (600mg x 2/day)+TDF+3TC" and patient/family-centered adherence has been reinforced. Since the first viral load (VL) measurement in 2010, the patient has had 12 VL tests with the VL ranging from 4.97 Log to 6.44 Log copies/mL and the CD4 count never exceeded 200 cells/µL. CONCLUSIONS: As African countries transition to dolutegravir-based regimens, prior raltegravir-exposure may prompt selection (and potential transmission) of dolutegravir-resistance, supporting case surveillance.

Increasing levels of pretreatment HIV drug resistance and safety concerns for dolutegravir use in women of reproductive age.

: Use of dolutegravir-based first-line antiretroviral therapy (ART) in response to rising levels of pretreatment HIV drug resistance (PDR) to non-nucleoside reverse transcriptase inhibitors (NNRTIs) may be limited, given safety concerns for birth defects in women of child-bearing potential. Pooled data from 11 nationally representative surveys show that NNRTI PDR in women is nearly twice that in men, exceeding 10% in 8 of 11 countries monitored, suggesting the urgent need for a non-NNRTI-based ART regimen in this population.

HIV virologic failure and its predictors among HIV-infected adults on antiretroviral therapy in the African Cohort Study.

INTRODUCTION: The 2016 WHO consolidated guidelines on the use of antiretroviral drugs defines HIV virologic failure for low and middle income countries (LMIC) as plasma HIV-RNA ≥ 1000 copies/mL. We evaluated virologic failure and predictors in four African countries. MATERIALS AND METHODS: We included HIV-infected participants on a WHO recommended antiretroviral therapy (ART) regimen and enrolled in the African Cohort Study between January 2013 and October 2017. Studied outcomes were virologic failure (plasma HIV-RNA ≥ 1000 copies/mL at the most recent visit), viraemia (plasma HIV-RNA ≥ 50 copies/mL at the most recent visit); and persistent viraemia (plasma HIV-RNA ≥ 50 copies/mL at two consecutive visits). Generalized linear models were used to estimate relative risks with their 95% confidence intervals. RESULTS: 2054 participants were included in this analysis. Viraemia, persistent viraemia and virologic failure were observed in 396 (19.3%), 160 (7.8%) and 184 (9%) participants respectively. Of the participants with persistent viraemia, only 57.5% (92/160) had confirmed virologic failure. In the multivariate analysis, attending clinical care site other than the Uganda sitebeing on 2nd line ART (aRR 1.8, 95% CI 1·28-2·66); other ART combinations not first line and not second line (aRR 3.8, 95% CI 1.18-11.9), a history of fever in the past week (aRR 3.7, 95% CI 1.69-8.05), low CD4 count (aRR 6.9, 95% CI 4.7-10.2) and missing any day of ART (aRR 1·8, 95% CI 1·27-2.57) increased the risk of virologic failure. Being on 2nd line therapy, the site where one receives care and CD4 count < 500 predicted viraemia, persistent viraemia and virologic failure. CONCLUSION: In conclusion, these findings demonstrate that HIV-infected patients established on ART for more than six months in the African setting frequently experienced viraemia while continuing to be on ART. The findings also show that being on second line, low CD4 count, missing any day of ART and history of fever in the past week remain important predictors of virologic failure that should trigger intensified adherence counselling especially in the absence of reliable or readily available viral load monitoring. Finally, clinical care sites are different calling for further analyses to elucidate on the unique features of these sites.

Brief Report: Differential Associations of Interleukin 6 and Intestinal Fatty Acid-Binding Protein With Progressive Untreated HIV-1 Infection in Rakai, Uganda.

The significance of HIV-associated immune activation and microbial translocation in Sub-Saharan African population remains poorly defined. We assessed biomarkers of inflammation, microbial translocation, and cellular activation and found most factors elevated in Ugandan HIV-1 seroconverters compared with community-matched controls. In contrast to previous findings in Western cohorts, C-reactive protein, neopterin, and intestinal fatty acid binding protein were not elevated. Higher T-cell activation and IL-6 were associated with faster disease progression. Surprisingly, intestinal fatty acid binding protein, indicative of enterocyte turnover, was higher in slow than in fast progressors. These data suggest differential relationships among biomarkers of intestinal barrier integrity and innate immune activation between developed countries and Sub-Saharan Africa.

Broadly cross-reactive HIV neutralizing human monoclonal antibody Fab selected by sequential antigen panning of a phage display library.

Identification of broadly cross-reactive human monoclonal antibodies (mAbs) has major implications for development of vaccines, inhibitors and research tools. Here we describe a sequential antigen panning (SAP) methodology that may facilitate the selection of such antibodies. An HIV-specific antibody Fab (m18) was selected from a human Fab phage-display library by SAP against several recombinant soluble HIV envelope glycoproteins (Envs) and Env-sCD4 complexes. This Fab bound to a variety of recombinant soluble Envs (gp140s) from primary HIV isolates representing different clades, and inhibited cell fusion and virus entry mediated by Envs of primary HIV isolates. The methodology and the results may have implications for development of HIV vaccines and inhibitors, as well as for identification of antibodies to conserved epitopes on rapidly mutating viruses and cells.

Evaluation of sequence ambiguities of the HIV-1 pol gene as a method to identify recent HIV-1 infection in transmitted drug resistance surveys.

Identification of recent HIV infection within populations is a public health priority for accurate estimation of HIV incidence rates and transmitted drug resistance at population level. Determining HIV incidence rates by prospective follow-up of HIV-uninfected individuals is challenging and serological assays have important limitations. HIV diversity within an infected host increases with duration of infection. We explore a simple bioinformatics approach to assess viral diversity by determining the percentage of ambiguous base calls in sequences derived from standard genotyping of HIV-1 protease and reverse transcriptase. Sequences from 691 recently infected (≤1 year) and chronically infected (>1 year) individuals from Sweden, Vietnam and Ethiopia were analyzed for ambiguity. A significant difference (p<0.0001) in the proportion of ambiguous bases was observed between sequences from individuals with recent and chronic infection in both HIV-1 subtype B and non-B infection, consistent with previous studies. In our analysis, a cutoff of <0.47% ambiguous base calls identified recent infection with a sensitivity and specificity of 88.8% and 74.6% respectively. 1,728 protease and reverse transcriptase sequences from 36 surveys of transmitted HIV drug resistance performed following World Health Organization guidance were analyzed for ambiguity. The 0.47% ambiguity cutoff was applied and survey sequences were classified as likely derived from recently or chronically infected individuals. 71% of patients were classified as likely to have been infected within one year of genotyping but results varied considerably amongst surveys. This bioinformatics approach may provide supporting population-level information to identify recent infection but its application is limited by infection with more than one viral variant, decreasing viral diversity in advanced disease and technical aspects of population based sequencing. Standardization of sequencing techniques and base calling and the addition of other parameters such as CD4 cell count may address some of the technical limitations and increase the usefulness of the approach.

The World Health Organization African region external quality assessment scheme for anti-HIV serology.

A regional external quality assessment scheme (REQAS) for anti-HIV serology aimed to objectively assess reliability and quality of HIV testing processes in the African region. This involved the distribution of proficiency testing (PT) panels to participating laboratories from 2002 to 2010. During the survey period, this included 16 distributions of PT panels to 49 laboratories in 30 countries, and the overall average score during the nine-year survey period was 98.9%, with a frequency of accurate detection, of anti-HIV-1 and/or anti-HIV-2 antibodies in the PT panels, ranging from 93% to 100%. Problems highlighted included lack of human resources and frequent stock outs of test kits, reagents and consumables for routine HIV testing. The design of the REQAS allowed appraisal of the reliability of anti-HIV serological testing methods utilised by laboratories for clinical assessment of patients and/or surveillance programmes. The REQAS was able to demonstrate that laboratories participating in the REQAS performed well and sustained their participation in the scheme. This bodes well for clinical diagnosis, surveillance and training activities at these reference laboratories.

The World Health Organization African region laboratory accreditation process: improving the quality of laboratory systems in the African region.

Few developing countries have established laboratory quality standards that are affordable and easy to implement and monitor. To address this challenge, the World Health Organization Regional Office for Africa (WHO AFRO) established a stepwise approach, using a 0- to 5-star scale, to the recognition of evolving fulfillment of the ISO 15189 standard rather than pass-fail grading. Laboratories that fail to achieve an assessment score of at least 55% will not be awarded a star ranking. Laboratories that achieve 95% or more will receive a 5-star rating. This stepwise approach acknowledges to laboratories where they stand, supports them with a series of evaluations to use to demonstrate improvement, and recognizes and rewards their progress. WHO AFRO's accreditation process is not intended to replace established ISO 15189 accreditation schemes, but rather to provide an interim pathway to the realization of international laboratory standards. Laboratories that demonstrate outstanding performance in the WHO-AFRO process will be strongly encouraged to enroll in an established ISO 15189 accreditation scheme. We believe that the WHO-AFRO approach for laboratory accreditation is affordable, sustainable, effective, and scalable.

Extensively cross-reactive anti-HIV-1 neutralizing antibodies induced by gp140 immunization.

An immunization regimen was evaluated in rabbits consisting of the soluble, oligomeric form of envelope glycoprotein of HIV-1, strain R2 (gp140(R2)), or the surface component of the same envelope (Env), gp120(R2), in the adjuvant AS02A. The gp140(R2) was selected based on its unusual CD4-independent phenotype and the exceptionally broad neutralizing response in the infected donor. The gp140(R2) immunogen induced antibodies that achieved 50% neutralization of 48/48, and 80% neutralization of 43/46 primary strains of diverse HIV-1 subtypes tested. The strains tested included members of standard panels of subtype B and C strains, and other diverse strains known to be neutralization resistant. The gp120(R2) induced antibodies that neutralized 9/48 of the same strains. Neutralization was IgG-mediated and HIV-1-specific. These results demonstrate that induction of truly broad spectrum neutralizing antibodies is an achievable goal in HIV-1 vaccine development.

Cross-reactive HIV-1 neutralizing monoclonal antibodies selected by screening of an immune human phage library against an envelope glycoprotein (gp140) isolated from a patient (R2) with broadly HIV-1 neutralizing antibodies.

Elicitation of broadly cross-reactive neutralizing antibodies (bcnAbs) in HIV infections is rare. To test the hypothesis that such antibodies could be elicited by HIV envelope glycoproteins (Envs) with unusual immunogenic properties and to identify novel bcnAbs, we used a soluble Env ectodomain (gp140) from a donor (R2) with high level of bcnAbs as an antigen for panning of an immune phage-displayed antibody library. The panning with the R2 Env resulted in significantly higher number of cross-reactive antibody clones than by using Envs from two other isolates (89.6 and IIIB). Two of the identified human monoclonal antibodies (hmAbs), m22 and m24, had sequences, neutralizing and binding activities similar or identical to those of the gp120-specific bcnAbs m18 and m14. The use of the R2 Env but not other Envs for panning resulted in the identification of a novel gp41-specific hmAb, m46. For several of the tested HIV-1 primary isolates its potency on molar basis was comparable to that of T20. It inhibited entry of primary isolates from different clades with an increased activity for cell lines with low CCR5 surface concentrations. The m46 neutralizing activity against a panel of clade C isolates was significantly higher in an assay based on peripheral blood mononuclear cells (4 out of 5 isolates were neutralized with an IC(50) in the range from 1.5 to 25 microg/ml) than in an assay based on a cell line with relatively high concentration of cell-surface-associated CCR5. In contrast to 2F5 and Z13, this antibody did not bind to denatured gp140 and gp41-derived peptides indicating a conformational nature of its epitope. It bound to a 5-helix bundle but not to N-heptad repeat coiled coils and a 6-helix bundle construct indicating contribution of both gp41 heptad repeats to its epitope and to a possible mechanism of neutralization. These results indicate that the R2 Env may contain unique exposed conserved epitopes that could contribute to its ability to elicit broadly cross-reactive antibodies in animals and humans; the newly identified antibodies may help in the development of novel vaccine immunogens and therapeutics.

Neutralization and infectivity characteristics of envelope glycoproteins from human immunodeficiency virus type 1 infected donors whose sera exhibit broadly cross-reactive neutralizing activity.

In this study, we tested the hypothesis that donors with broadly cross-reactive HIV-1 neutralizing (BCN) sera are infected with viruses encoding envelope glycoproteins (Envs) with unusual immunogenic properties. Cloned env genes were from samples of donors previously identified as having BCN antibodies (BCN donors) and from other donors not known to have such antibodies (non-BCN donors). Neutralization properties of viruses pseudotyped with BCN and non-BCN Envs were determined using BCN, non-BCN sera and broadly cross-neutralizing monoclonal antibodies (Mabs). BCN sera neutralized with higher frequency and geometric mean titers than non-BCN sera. Viruses pseudotyped with BCN Envs were mostly resistant to neutralization by anti-gp120 Mabs but tended to be more sensitive to the anti-gp41 Mabs, 2F5 and 4E10 than non-BCN Env-pseudotyped viruses. Sequence analysis of clones obtained from sequential samples of two BCN donors revealed respective 2F5 epitope mutations T662A and K665T. The K665T mutation evolved as the predominant genotype in the respective donor, consistent with an escape mutation event. The A662T mutation reduced sensitivity to 4E10, as well as 2F5 and homologous sera, consistent with neutralization escape mutation and targeting of the 2F5 epitope region by the serum. Our study suggests that viruses infecting these BCN donors encoded Envs that may have been unusually competent for induction of antibodies against the membrane proximal epitope region (MPER) of gp41, and these Envs may be useful vaccine components.

Identification and characterization of a new cross-reactive human immunodeficiency virus type 1-neutralizing human monoclonal antibody.

The identification and characterization of new human monoclonal antibodies (hMAbs) able to neutralize primary human immunodeficiency virus type 1 (HIV-1) isolates from different subtypes may help in our understanding of the mechanisms of virus entry and neutralization and in the development of entry inhibitors and vaccines. For enhanced selection of broadly cross-reactive antibodies, soluble HIV-1 envelope glycoproteins (Envs proteins) from two isolates complexed with two-domain soluble CD4 (sCD4) were alternated during panning of a phage-displayed human antibody library; these two Env proteins (89.6 and IIIB gp140s), and one additional Env (JR-FL gp120) alone and complexed with sCD4 were used for screening. An antibody with relatively long HCDR3 (17 residues), designated m14, was identified that bound to all antigens and neutralized heterologous HIV-1 isolates in multiple assay formats. Fab m14 potently neutralized selected well-characterized subtype B isolates, including JRCSF, 89.6, IIIB, and Yu2. Immunoglobulin G1 (IgG1) m14 was more potent than Fab m14 and neutralized 7 of 10 other clade B isolates; notably, although the potency was on average significantly lower than that of IgG1 b12, IgG1 m14 neutralized two of the isolates with significantly lower 50% inhibitory concentrations than did IgG1 b12. IgG1 m14 neutralized four of four selected clade C isolates with potency higher than that of IgG1 b12. It also neutralized 7 of 17 clade C isolates from southern Africa that were difficult to neutralize with other hMAbs and sCD4. IgG1 m14 neutralized four of seven primary HIV-1 isolates from other clades (A, D, E, and F) much more efficiently than did IgG1 b12; for the other three isolates, IgG b12 was much more potent. Fab m14 bound with high (nanomolar range) affinity to gp120 and gp140 from various isolates; its binding was reduced by soluble CD4 and antibodies recognizing the CD4 binding site (CD4bs) on gp120, and its footprint as defined by alanine-scanning mutagenesis overlaps that of b12. These results suggest that m14 is a novel CD4bs cross-reactive HIV-1-neutralizing antibody that exhibits a different inhibitory profile compared to the only known potent broadly neutralizing CD4bs human antibody, b12, and may have implications for our understanding of the mechanisms of immune evasion and for the development of inhibitors and vaccines.

Quantification of Human T-lymphotropic virus type I (HTLV-I) provirus load in a rural West African population: no enhancement of human immunodeficiency virus type 2 pathogenesis, but HTLV-I provirus load relates to mortality.

Human T-lymphotropic virus type I (HTLV-I) provirus load was examined in a cohort of a population in Guinea-Bissau among whom human immunodeficiency virus (HIV) type 2 is endemic. Geometric mean of HIV-2 RNA load among HTLV-I-coinfected subjects was significantly lower than that in subjects infected with HIV-2 alone (212 vs. 724 copies/mL; P=.02). Adjusted for age, sex, and HIV status, the risk of death increased with HTLV-I provirus load; mortality hazard ratio was 1.59 for each log10 increase in HTLV-I provirus copies (P=.038). There is no enhancing effect of HTLV-I coinfection on HIV-2 disease, but high HTLV-I provirus loads may contribute to mortality.