Chronic Human Pegivirus 2 without Hepatitis C Virus Co-infection.

Most human pegivirus 2 (HPgV-2) infections are associated with past or current hepatitis C virus (HCV) infection. HPgV-2 is thought to be a bloodborne virus: higher prevalence of active infection has been found in populations with a history of parenteral exposure to viruses. We evaluated longitudinally collected blood samples obtained from injection drug users (IDUs) for active and resolved HPgV-2 infections using a combination of HPgV-2-specific molecular and serologic tests. We found evidence of HPgV-2 infection in 11.2% (22/197) of past or current HCV-infected IDUs, compared with 1.9% (4/205) of an HCV-negative IDU population. Testing of available longitudinal blood samples from HPgV-2-positive participants identified 5 with chronic infection (>6 months viremia in >3 timepoints); 2 were identified among the HCV-positive IDUs and 3 among the HCV-negative IDUs. Our findings indicate that HPgV-2 can establish chronic infection and replicate in the absence of HCV.

Hepatitis C virus surveillance and identification of human pegivirus 2 in a large Cameroonian cohort.

The prevalence of chronic hepatitis C virus (HCV) and the presence of human pegivirus 2 (HPgV-2) have not been examined in Cameroon, although HCV has been associated with HPgV-2 infections previously. Herein we aimed to characterize the burden and genetic diversity of HCV and the presence of HPgV-2 in Cameroon. Retrospective plasma specimens collected from N = 12 369 consenting subjects in South Cameroon from 2013 to 2016 were included in the study. The majority (97.1%) of participants were patients seeking health care. All specimens were screened for HCV using the Abbott RealTime HCV viral load assay and positive specimens with remaining volume were also screened for HPgV-2 antibodies on the Abbott ARCHITECT instrument, followed by molecular characterization. Overall, HCV RNA was detected in 305 (2.47%; 95% CI: 2.21%-2.75%) specimens. Notably, the prevalence of HCV RNA was 9.09% amongst participants over age 40 and 3.81% amongst males. Phylogenetic classification of N = 103 HCV sequences identified genotypes 1 (19.4%), 2 (15.5%) and 4 (65.1%) within the study cohort. Amongst HCV RNA-positive specimens, N = 28 (10.6%; 95% CI: 7.44%-14.90%) specimens also had detectable HPgV-2 antibodies. Of these, N = 2 viremic HPgV-2 infections were confirmed by sequencing and shared 93-94 median % identity with strains found on other continents. This is the first study to determine the prevalence of chronic HCV in Cameroon, and the discovery of HPgV-2 in this study cohort expands the geography of HPgV-2 to the African continent, indicating a widespread distribution exists.

Sensitive Next-Generation Sequencing Method Reveals Deep Genetic Diversity of HIV-1 in the Democratic Republic of the Congo.

As the epidemiological epicenter of the human immunodeficiency virus (HIV) pandemic, the Democratic Republic of the Congo (DRC) is a reservoir of circulating HIV strains exhibiting high levels of diversity and recombination. In this study, we characterized HIV specimens collected in two rural areas of the DRC between 2001 and 2003 to identify rare strains of HIV. The env gp41 region was sequenced and characterized for 172 HIV-positive specimens. The env sequences were predominantly subtype A (43.02%), but 7 other subtypes (33.14%), 20 circulating recombinant forms (CRFs; 11.63%), and 20 unclassified (11.63%) sequences were also found. Of the rare and unclassified subtypes, 18 specimens were selected for next-generation sequencing (NGS) by a modified HIV-switching mechanism at the 5' end of the RNA template (SMART) method to obtain full-genome sequences. NGS produced 14 new complete genomes, which included pure subtype C (n = 2), D (n = 1), F1 (n = 1), H (n = 3), and J (n = 1) genomes. The two subtype C genomes and one of the subtype H genomes branched basal to their respective subtype branches but had no evidence of recombination. The remaining 6 genomes were complex recombinants of 2 or more subtypes, including subtypes A1, F, G, H, J, and K and unclassified fragments, including one subtype CRF25 isolate, which branched basal to all CRF25 references. Notably, all recombinant subtype H fragments branched basal to the H clade. Spatial-geographical analysis indicated that the diverse sequences identified here did not expand globally. The full-genome and subgenomic sequences identified in our study population significantly increase the documented diversity of the strains involved in the continually evolving HIV-1 pandemic.IMPORTANCE Very little is known about the ancestral HIV-1 strains that founded the global pandemic, and very few complete genome sequences are available from patients in the Congo Basin, where HIV-1 expanded early in the global pandemic. By sequencing a subgenomic fragment of the HIV-1 envelope from study participants in the DRC, we identified rare variants for complete genome sequencing. The basal branching of some of the complete genome sequences that we recovered suggests that these strains are more closely related to ancestral HIV-1 strains than to previously reported strains and is evidence that the local diversification of HIV in the DRC continues to outpace the diversity of global strains decades after the emergence of the pandemic.

Use of a multifaceted approach to analyze HIV incidence in a cohort study of women in the United States: HIV Prevention Trials Network 064 Study.

BACKGROUND: Reliable methods for estimating the incidence of human immunodeficiency virus (HIV) infection are needed to monitor the epidemic, identify at-risk populations, and evaluate HIV prevention strategies. We used a multifaceted approach to estimate HIV incidence in the HIV Prevention Trials Network (HPTN) 064 study. METHODS: The HPTN 064 study enrolled 2067 HIV-seronegative women and 32 HIV-seropositive women with no prior HIV infection diagnosis. Women were followed for up to 12 months. HIV incidence estimates were based on (1) detection of acute HIV infection, (2) documentation of HIV seroconversion, and (3) detection of recent HIV infection, using a multiassay algorithm (MAA). RESULTS: Two women had acute HIV infection at enrollment, 4 seroconverted, and 2 were identified as recently infected at enrollment using the MAA. The annual HIV incidence estimate based on acute infection at enrollment (2.52% [95% confidence interval {CI}, .17%-9.33%], using a 14-day window period) was higher than the estimate based on seroconversion (0.24% [95% CI, .07%-.62%]; P = .027). Incidence estimates obtained using the MAA at enrollment and at the end of study were 0.25% (95% CI, .03%-.93%) and 0.13% (95% CI, .006%-.76%), respectively. CONCLUSIONS: We detected a high frequency of acute infection at enrollment. Cross-sectional HIV incidence estimates obtained using the MAA were similar to the longitudinal estimate based on HIV seroconversion. CLINICAL TRIALS REGISTRATION: NCT00995176.

Characterization of HBV surface antigen isoforms in the natural history and treatment of HBV infection.

BACKGROUND: The loss of HBV HBsAg or functional cure is a desirable goal of hepatitis B management. The relative abundances of HBsAg isoforms may offer additional diagnostic and predicting values. To evaluate the clinical utility of HBsAg isoforms, we developed novel prototype assays on the ARCHITECT automated serology platform that specifically detects total-HBsAg (T-HBsAg), large (L-HBsAg), and middle (M-HBsAg) products of the S gene to determine the isoform composition of human specimens from acute and chronic HBV infection and during long-term nucleos(t)ide analog therapy. RESULTS: In the early phase of acute HBV infection, L-HBsAg and M-HBsAg emerged within days and were in parallel to T-HBsAg during the entire course of infection. M-HBsAg levels were consistently higher than L-HBsAg levels. Patients with HBeAg(+) chronic hepatitis B had higher T-HBsAg, M-HBsAg, and L-HBsAg levels compared with HBeAg(-) patients. Correlations of M-HBsAg and L-HBsAg to T-HBsAg were similar in both. In contrast, there was no strong correlation between L-HBsAg or M-HBsAg with HBV DNA levels. During long-term nucleos(t)ide analog treatment, changes in HBsAg isoform abundance were proportional to T-HBsAg regardless of treatment responses for both HBeAg(+) and HBeAg(-) chronic hepatitis B. A larger sample size may be necessary to detect a significant difference. CONCLUSION: HBsAg isoform compositions parallel T-HBsAg levels in both acute and chronic hepatitis B infection. L-HBsAg and M-HBsAg individual biomarkers do not appear to provide an additional diagnostic benefit for staging chronic disease or monitoring response to treatment with current therapies.

Confirmation of putative HIV-1 group P in Cameroon.

We report the second human immunodeficiency virus (HIV) belonging to the new HIV type 1 (HIV-1) group P lineage that is closely related to the simian immunodeficiency virus found in gorillas. This virus was identified in an HIV-seropositive male hospital patient in Cameroon, confirming that the group P virus is circulating in humans. Results from screening 1,736 HIV-seropositive specimens collected in Cameroon indicate that HIV-1 group P infections are rare, accounting for only 0.06% of HIV infections. Despite its rarity, group P shows evidence of adaptation to humans.

HIV surveillance in a large, community-based study: results from the pilot study of Project Accept (HIV Prevention Trials Network 043).

BACKGROUND: Project Accept is a community randomized, controlled trial to evaluate the efficacy of community mobilization, mobile testing, same-day results, and post-test support for the prevention of HIV infection in Thailand, Tanzania, Zimbabwe, and South Africa. We evaluated the accuracy of in-country HIV rapid testing and determined HIV prevalence in the Project Accept pilot study. METHODS: Two HIV rapid tests were performed in parallel in local laboratories. If the first two rapid tests were discordant (one reactive, one non-reactive), a third HIV rapid test or enzyme immunoassay was performed. Samples were designated HIV NEG if the first two tests were non-reactive, HIV DISC if the first two tests were discordant, and HIV POS if the first two tests were reactive. Samples were re-analyzed in the United States using a panel of laboratory tests. RESULTS: HIV infection status was correctly determined based on-in country testing for 2,236 (99.5%) of 2,247 participants [7 (0.37%) of 1,907 HIV NEG samples were HIV-positive; 2 (0.63%) of 317 HIV POS samples were HIV-negative; 2 (8.3%) of 24 HIV DISC samples were incorrectly identified as HIV-positive based on the in-country tie-breaker test]. HIV prevalence was: Thailand: 0.6%, Tanzania: 5.0%, Zimbabwe 14.7%, Soweto South Africa: 19.4%, Vulindlela, South Africa: 24.4%, (overall prevalence: 14.4%). CONCLUSIONS: In-country testing based on two HIV rapid tests correctly identified the HIV infection status for 99.5% of study participants; most participants with discordant HIV rapid tests were not infected. HIV prevalence varied considerably across the study sites (range: 0.6% to 24.4%). TRIAL REGISTRATION: ClinicalTrials.gov registry number NCT00203749.

Expanding access to SARS-CoV-2 IgG and IgM serologic testing using fingerstick whole blood, plasma, and rapid lateral flow assays.

Serologic testing for SARS-CoV-2 antibodies can be used to confirm diagnosis, estimate seroprevalence, screen convalescent plasma donors, and assess vaccine efficacy. Dried blood spot (DBS) samples have been used for serology testing of various diseases in resource-limited settings. We examined the use of DBS samples and capillary blood (fingerstick) plasma collected in Microtainer tubes for SARS-CoV-2 testing with the automated Abbott ARCHITECT™ SARS-CoV-2 IgG and IgM assays and use of venous whole blood with a prototype PANBIO™ rapid point-of-care lateral flow SARS-CoV-2 IgG assay. The ARCHITECT™ SARS-CoV-2 IgG assay was initially optimized for use with DBS, venous and capillary plasma, and venous whole blood collected from patients with symptoms and PCR-confirmed COVID-19 and negative asymptomatic controls. Linearity and reproducibility was confirmed with 3 contrived DBS samples, along with sample stability and signal recovery after 14 days. ARCHITECT™ SARS-CoV-2 IgG and IgM assay results showed high concordance between fingerstick DBS and venous DBS samples, and between fingerstick DBS and venous whole blood samples (n = 61). Fingerstick plasma collected in Microtainer tubes (n = 109) showed 100% concordant results (R2=0.997) with matched patient venous plasma on the ARCHITECT™ SARS-CoV-2 IgG assay. High concordance of assay results (92.9% positive, 100% negative) was also observed for the PANBIO™ SARS-CoV-2 IgG assay compared to the ARCHITECT™ SARS-CoV-2 IgG assay run with matched venous plasma (n = 61). Fingerstick DBS and plasma samples are easy and inexpensive to collect and, along with the use of rapid point-of-care testing platforms, will expand access to SARS-CoV-2 serology testing, particularly in resource-limited areas.

SARS-CoV-2 antibody magnitude and detectability are driven by disease severity, timing, and assay.

Interpretation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serosurveillance studies is limited by poorly defined performance of antibody assays over time in individuals with different clinical presentations. We measured antibody responses in plasma samples from 128 individuals over 160 days using 14 assays. We found a consistent and strong effect of disease severity on antibody magnitude, driven by fever, cough, hospitalization, and oxygen requirement. Responses to spike protein versus nucleocapsid had consistently higher correlation with neutralization. Assays varied substantially in sensitivity during early convalescence and time to seroreversion. Variability was dramatic for individuals with mild infection, who had consistently lower antibody titers, with sensitivities at 6 months ranging from 33 to 98% for commercial assays. Thus, the ability to detect previous infection by SARS-CoV-2 is highly dependent on infection severity, timing, and the assay used. These findings have important implications for the design and interpretation of SARS-CoV-2 serosurveillance studies.

SARS-CoV-2 antibody magnitude and detectability are driven by disease severity, timing, and assay.

Serosurveillance studies are critical for estimating SARS-CoV-2 transmission and immunity, but interpretation of results is currently limited by poorly defined variability in the performance of antibody assays to detect seroreactivity over time in individuals with different clinical presentations. We measured longitudinal antibody responses to SARS-CoV-2 in plasma samples from a diverse cohort of 128 individuals over 160 days using 14 binding and neutralization assays. For all assays, we found a consistent and strong effect of disease severity on antibody magnitude, with fever, cough, hospitalization, and oxygen requirement explaining much of this variation. We found that binding assays measuring responses to spike protein had consistently higher correlation with neutralization than those measuring responses to nucleocapsid, regardless of assay format and sample timing. However, assays varied substantially with respect to sensitivity during early convalescence and in time to seroreversion. Variations in sensitivity and durability were particularly dramatic for individuals with mild infection, who had consistently lower antibody titers and represent the majority of the infected population, with sensitivities often differing substantially from reported test characteristics (e.g., amongst commercial assays, sensitivity at 6 months ranged from 33% for ARCHITECT IgG to 98% for VITROS Total Ig). Thus, the ability to detect previous infection by SARS-CoV-2 is highly dependent on the severity of the initial infection, timing relative to infection, and the assay used. These findings have important implications for the design and interpretation of SARS-CoV-2 serosurveillance studies.

Brief Report: Complete Genome Sequence of CG-0018a-01 Establishes HIV-1 Subtype L.

BACKGROUND: The full spectrum of HIV-1 diversity can be found in Central Africa, including 2 divergent HIV-1 strains collected in 1983 and 1990 in Democratic Republic of Congo (DRC) that were preliminarily classified as group M subtype L. However, a third epidemiologically distinct subtype L genome must be identified to designate L as a true subtype. METHODS: Specimen CG-0018a-01 was collected in 2001 in DRC as part of an HIV diversity study. Previous subgenomic HIV-1 sequences from this specimen branched closely with proposed subtype L references. Metagenomic next-generation sequencing (mNGS) and HIV-specific target-enriched (HIV-xGen) libraries were combined for NGS to extend genome coverage. mNGS reads were analyzed for the presence of other coinfections with the sequence-based ultrarapid pathogen identification bioinformatics pipeline. RESULTS: A complete HIV-1 genome was generated with an average coverage depth of 47,783×. After bioinformatic analysis also identified hepatitis B virus reads, a complete hepatitis B virus genotype A genome was assembled with an average coverage depth of 73,830×. The CG-0018a-01 HIV-1 genome branched basal to the 2 previous putative subtype L strains with strong bootstrap support of 100. With no evidence of recombination present, the strain was classified as subtype L. CONCLUSIONS: The CG-0018a-01 HIV-1 genome establishes subtype L and confirms ongoing transmission in DRC as recently as 2001. Since CG-0018a-01 is more closely related to an ancestral strain than to isolates from 1983 to 1990, additional strains are likely circulating in DRC and possibly elsewhere.

Diverse HCV Strains And HIV URFS Identified Amongst People Who Inject Drugs In India.

Although the prevalences of HIV and HCV are significantly higher amongst PWID in India compared to the general population, the strains circulating within this group have not been well-characterized. Through subgenomic sequencing of viruses present in residual plasma from an HIV/HCV prevalence study conducted amongst PWID across five cities in India in 2016-2017, a total of N = 498 HCV and N = 755 HIV strains were classified from N = 975 study participants. Considerable HCV diversity was identified, with different strains predominating in each region of the country. Overall, the most common strain was genotype 3a (39.0%), with genotypes 1a (26.9%), 1b (3.0%), 1c (0.2%), 3b (20.7%), 3i (2.0%), 4a (0.2%), 4d (1.0%), 6 (1.8%), 6n (4.8%), 6 v (0.2%) and one unclassifiable recombinant specimen (0.2%) also identified. The majority of the HIV specimens were subtype C (96.7%), although subtype A (0.4%), CRF01_AE (0.4%) and unique recombinant forms (URFs, 2.5%) were also detected. Notably, the geographical restriction of HIV subtype A and CRF01_AE, and HCV genotypes 4 and 6 to specific sites suggests distinct novel introductions of HIV and HCV into PWID populations, potentially via drug trafficking routes from neighboring countries where these strains are common.

Human pegivirus 2 exhibits minimal geographic and temporal genetic diversity.

We applied an NGS based target capture approach to amplify HPgV-2 sequences from metagenomic libraries and enable full genome characterization. Despite expanded geographical sampling, sequence variability remains low, with diversity concentrated in approximately 3.3% of all amino acids. Serial samples from one HPgV-2 positive individual co-infected with comparable titers of HIV, HCV, and GBV-C showed that HPgV-2 remains highly stable over several weeks compared to other RNA viruses, despite a similarly error-prone polymerase. The consistent epidemiological association with and structural similarities to HCV, and the weak positive correlation of HCV and HPgV-2 titers shown here, suggests it may benefit from co-infection. While minimal selective pressure on HPgV-2 to evolve could suggest fitness, the rarity of HPgV-2 and the tight phylogenetic clustering of global strains likely indicates origination from a common source and a virus that is ill-suited to its host. Sporadic infections may explain the limited genetic diversity observed worldwide.

A comparative evaluation between the Abbott Panbio™ COVID-19 IgG/IgM rapid test device and Abbott Architect™ SARS CoV-2 IgG assay.

INTRODUCTION: Antibodies to SARS-CoV-2 serve as critical diagnostic markers for determining how broadly the COVID-19 pandemic has spread, confirming patient recovery, monitoring potential long-term effects of infection, and evaluating potential protection from reinfection. As new antibody tests become available, it is important to evaluate their performance and utility. The aim of this study was to compare the performance of the Abbott PanbioTM COVID-19 IgG/IgM Rapid Test Device against the Abbott ArchitectTM SARS CoV-2 IgG Assay for the detection of the COVID-19 IgG antibody. METHODS: Two panels of specimens were utilized to challenge both antibody tests: (1) a set of 150 prepandemic negative specimens collected in 2014, and (2) a set of 122 specimens from 87 hospitalized COVID-19 patients in the US and UK that were confirmed with a positive SARS-CoV-2 RNA test result. RESULTS: The ArchitectTM test had a specificity of 100 % and sensitivity of 99.1 % and 93.9 % when excluding or including immunocompromised patients, respectively for specimens collected >14 days post symptom onset or >5 days post-RNA testing. The PanbioTM test had 99.3 % agreement to ArchitectTM. Notably, N = 6 immune-compromised individuals were identified that did not develop detectable antibodies by day 30. CONCLUSION: There is good concordance between the ArchitectTM SARS CoV-2 IgG Assay and PanbioTM COVID-19 IgG/IgM Rapid Test Device for the detection of SARS CoV-2 IgG.

New Genomes from the Congo Basin Expand History of CRF01_AE Origin and Dissemination.

Although the first HIV circulating recombinant form (CRF01_AE) is the predominant strain in many Asian countries, it is uncommonly found in the Congo Basin from where it first originated. To fill the gap in the evolutionary history of this important strain, we sequenced near complete genomes from HIV samples with subgenomic CRF01_AE regions collected in Cameroon and the Democratic Republic of the Congo from 2001 to 2006. HIV genomes were generated from N = 13 plasma specimens by next-generation sequencing of metagenomic libraries prepared with spiked primers targeting HIV, followed by Sanger gap-filling. Genome sequences were aligned to reference strains, including Asian and African CRF01_AE sequences, and evaluated by phylogenetic and recombinant analysis to identify four CRF01_AE strains from Cameroon. We also identified two CRF02, one CRF27, and six unique recombinant form genomes (01|A1|G, 01|02|F|U, F|G|01, A1|D|01, F|G|01, and A1|G|01). Phylogenetic analysis, including the four new African CRF01_AE genomes, placed these samples as a bridge between basal Central African Republic CRF01_AE strains and all Asian, European, and American CRF01_AE strains. Molecular dating confirmed previous estimates indicating that the most recent common CRF01_AE ancestor emerged in the early 1970s (1968-1970) and spread beyond Africa around 1980 to Asia. The new sequences and analysis presented in this study expand the molecular history of the CRF01_AE clade, and are illustrated in an interactive Next Strain phylogenetic tree, map, and timeline at (https://nextstrain.org/community/EduanWilkinson/hiv-1_crf01).

Assessment of the ability of a fourth-generation immunoassay for human immunodeficiency virus (HIV) antibody and p24 antigen to detect both acute and recent HIV infections in a high-risk setting.

An immunoassay (IA) that simultaneously detects both antibody to human immunodeficiency virus (HIV) and HIV p24 antigen (Architect HIV Ag/Ab Combo) was evaluated for its ability to detect HIV infection by using a panel of specimens collected from individuals recently infected with HIV type 1 (HIV-1). This IA was found to be capable of detecting the majority (89%) of infections, including 80% of those considered acute infections based on the presence of HIV RNA and the lack of detectable antibody to HIV. Substantial improvements in detection of recent infections by the Architect HIV Ag/Ab Combo relative to previous generations of IAs as well as the capacity to detect acute infections have important implications for HIV prevention strategies.

HIV type 2 intergroup recombinant identified in Cameroon.

A unique HIV-2 intergroup recombinant strain was identified in Cameroon. The virus, CM-03-510-03, was amplified from blood collected from a 47-year-old female patient in Douala, Cameroon in 2003 who was seroreactive for HIV-2. A near full-length genome 9089 nucleotides in length was amplified from proviral DNA. The genome for CM-03-510-03 is composed of segments of HIV-2 groups A and B with four recombination break-points and has open reading frames for all the structural and regulatory genes. A comparison of CM-03-510-03 to the only previously reported HIV-2 intergroup recombinant shows that the two strains share one recombination breakpoint but are otherwise distinct from each other. Similar to HIV-1, HIV-2 intergroup recombination is an indication that coinfection with more than one strain has occurred in individuals and is a mechanism that increases strain genetic diversity.

ARCHITECT HIV Combo Ag/Ab and RealTime HIV-1 Assays Detect Diverse HIV Strains in Clinical Specimens.

Periodic evaluation of the impact of viral diversity on diagnostic tests is critical to ensure current technologies are keeping pace with viral evolution. To determine whether HIV diversity impacts the ARCHITECT HIV Combo Ag/Ab (HIV Combo) or RealTime HIV-1 (RT) assays, a set of N = 199 HIV clinical specimens from Cameroon, Senegal, Saudi Arabia, and Thailand were sequenced and tested in both assays. The panel included historical groups N and P specimens and a newly identified group N specimen. These and specimens classified as H, U (unclassified)/URF (unique recombinant form), CRF (circulating recombinant form) 01, 02, 06, 09, 11, 13, 18, 22, 37, and 43 were detected by both the RT assay (1.75-6.84 log copies/ml) and the HIV Combo assay (3.26-1121.96 sample to cutoff ratios). Sequence alignment identified 3 or fewer mismatches to the RT assay oligos in 82.4% of samples. Altogether, these data demonstrate the HIV Combo and RT assays detect diverse strains of HIV in clinical specimens.

HIV-1 strains identified in Brazilian blood donors: significant prevalence of B/F1 recombinants.

In the Brazilian HIV-1 epidemic subtypes B, C, and F1 are cocirculating in the high risk population groups, and there is a high prevalence of intersubtype recombinant forms. The dynamic nature of the HIV epidemic in Brazil led us to study HIV-1 subtypes present in HIV-infected blood donations collected from 2001 to 2003. Donations from 91 seropositive donors were evaluated. Genetic subtype was obtained for 88 specimens based on sequence analysis of gag p24, pol IN, and env gp41 IDR. HIV-1 subtype B was the predominant strain present in the donor population (73.9%). A significant prevalence of intersubtype recombinants of subtypes B and F1 was found (22.7%). Subtype C (1.1%) and F1 (2.3%) were rare. None of the B/F1 recombinants is CRF28_BF or CRF29_BF. The high level of unique B/F1 recombinant strains in this population demonstrates the dynamic and complex nature of the HIV epidemic in Brazil.

Identification of HIV type 1 group N infections in a husband and wife in Cameroon: viral genome sequences provide evidence for horizontal transmission.

HIV-1 is classified into three groups, M (major), N (non-M non-O), and O (outlier); each group arose from a separate transmission of SIVcpz into humans. HIV-1 group N was recently discovered and infections with this virus are rare with only eight documented cases. All group N infections have been found in Cameroon and there is no evidence of direct linkage between the infected patients. We report here the identification of HIV-1 group N infections in a husband and wife. The group N infection in the husband, 1131-03, was identified first based on seroreactivity in peptide EIAs and confirmed by PCR amplification of group N viral sequences. Subsequently the wife, 1015-04, was evaluated and confirmed to also be infected with a group N virus. Near full-length viral genomes were amplified and sequenced from each patient's specimen. The low level of diversity between the two viral sequences provides evidence of horizontal transmission of group N from one spouse to the other. Patient 1131-03 was receiving antiviral therapy consisting of reverse transcriptase inhibitors; the treatment appears effective for suppression of group N viral replication based on apparently low viral load in plasma specimens collected from the patient and the absence of drug resistance mutations in RT sequences amplified from 1131-03. This report brings to 10 the number of group N infections identified and to 5 the number of group N genomes sequenced. Although group N infections continue to be rare, group N is a pathogenic virus and its prevalence needs to be monitored.