Principles and Strategies for Effective Teaching: A Workshop for Pre- and Postdoctoral Trainees in the Biomedical Sciences

The 2012 National Institutes of Health (NIH) Biomedical Workforce Working Group Report documented that graduate training in the biomedical sciences predominantly prepares people for academic research positions. The report recommended that NIH provide funds for institutions to develop broader career development opportunities, including training related to teaching. Indeed, teaching is not only a required component of any faculty position, it is the primary task for trainees who seek employment at small liberal arts colleges and other primarily undergraduate institutions. NIH funding for the BEST (Broadening Experiences in Scientific Training) programs allowed us to develop a six-week training workshop for bioscience trainees to introduce participants to research-based, student-centered pedagogies and instructional design techniques and to inspire them to view teaching as an intellectual endeavor. The methods and outcomes of our case study should be applicable in a variety of programs and organizations, especially those with a separate health science campus, where faculty mentors often do not teach many classes and there are few, if any, apprenticeship-teaching opportunities for trainees.

Parental involvement in decision making about intracranial pressure monitor placement in children with traumatic brain injury

OBJECTIVE

Little is known about how parents of children with traumatic brain injury (TBI) participate or feel they should participate in decision making regarding placing an intracranial pressure (ICP) monitor. The objective of this study was to identify the perspectives and decisional or information needs of parents whose child sustained a TBI and may require an ICP monitor.

METHODS

This was a qualitative study at one US level I pediatric trauma center. The authors conducted in-depth semistructured interviews with 1) parents of critically injured children who have sustained a TBI and 2) clinicians who regularly care for children with TBI.

RESULTS

The authors interviewed 10 parents of 7 children (60% were mothers and 80% were white) and 28 clinicians (17 ICU clinicians and 11 surgeons). Overall, the authors found concordance between and among parents and clinicians about parental involvement in ICP monitor decision making. Parents and clinicians agreed that decision making about ICP monitoring in children who have suffered TBI is not and should not be shared between the parents and clinicians. The concordance was represented in 3 emergent themes. Parents wanted transparency, communication, and information (theme 2), but the life-threatening context of this decision (theme 1) created an environment where all involved reflected a clear preference for paternalism (theme 3).

CONCLUSIONS

The clear and concordant preference for clinician paternalistic decision making coupled with the parents' needs to be informed suggests that a decision support tool for this decision should be clinician facing and should emphasize transparency in collaborative decision making between clinicians.

TGFβ1-Mediated SMAD3 Enhances PD-1 Expression on Antigen-Specific T Cells in Cancer

Programmed death-1 (PD-1) is a coinhibitory receptor that downregulates the activity of tumor-infiltrating lymphocytes (TIL) in cancer and of virus-specific T cells in chronic infection. The molecular mechanisms driving high PD-1 expression on TILs have not been fully investigated. We demonstrate that TGFβ1 enhances antigen-induced PD-1 expression through SMAD3-dependent, SMAD2-independent transcriptional activation in T cells in vitro and in TILs in vivo The PD-1^hi subset seen in CD8⁺ TILs is absent in Smad3-deficient tumor-specific CD8⁺ TILs, resulting in enhanced cytokine production by TILs and in draining lymph nodes and antitumor activity. In addition to TGFβ1's previously known effects on T-cell function, our findings suggest that TGFβ1 mediates T-cell suppression via PD-1 upregulation in the tumor microenvironment (TME). They highlight bidirectional cross-talk between effector TILs and TGFβ-producing cells that upregulates multiple components of the PD-1 signaling pathway to inhibit antitumor immunity.

SIGNIFICANCE

Engagement of the coinhibitory receptor PD-1 or its ligand, PD-L1, dramatically inhibits the antitumor function of TILs within the TME. Our findings represent a novel immunosuppressive function of TGFβ and demonstrate that TGFβ1 allows tumors to evade host immune responses in part through enhanced SMAD3-mediated PD-1 expression on TILs. Cancer Discov; 6(12); 1366-81. ©2016 AACRThis article is highlighted in the In This Issue feature, p. 1293.

The Causal Role of IL-4 and IL-13 in Schistosoma mansoni Pulmonary Hypertension

RATIONALE

The etiology of schistosomiasis-associated pulmonary arterial hypertension (PAH), a major cause of PAH worldwide, is poorly understood. Schistosoma mansoni exposure results in prototypical type-2 inflammation. Furthermore, transforming growth factor (TGF)-β signaling is required for experimental pulmonary hypertension (PH) caused by Schistosoma exposure.

OBJECTIVES

We hypothesized type-2 inflammation driven by IL-4 and IL-13 is necessary for Schistosoma-induced TGF-β-dependent vascular remodeling.

METHODS

Wild-type, IL-4(-/-), IL-13(-/-), and IL-4(-/-)IL-13(-/-) mice (C57BL6/J background) were intraperitoneally sensitized and intravenously challenged with S. mansoni eggs to induce experimental PH. Right ventricular catheterization was then performed, followed by quantitative analysis of the lung tissue. Lung tissue from patients with schistosomiasis-associated and connective tissue disease-associated PAH was also systematically analyzed.

MEASUREMENTS AND MAIN RESULTS

Mice with experimental Schistosoma-induced PH had evidence of increased IL-4 and IL-13 signaling. IL-4(-/-)IL-13(-/-) mice, but not single knockout IL-4(-/-) or IL-13(-/-) mice, were protected from Schistosoma-induced PH, with decreased right ventricular pressures, pulmonary vascular remodeling, and right ventricular hypertrophy. IL-4(-/-)IL-13(-/-) mice had less pulmonary vascular phospho-signal transducer and activator of transcription 6 (STAT6) and phospho-Smad2/3 activity, potentially caused by decreased TGF-β activation by macrophages. In vivo treatment with a STAT6 inhibitor and IL-4(-/-)IL-13(-/-) bone marrow transplantation also protected against Schistosoma-PH. Lung tissue from patients with schistosomiasis-associated and connective tissue disease-associated PAH had evidence of type-2 inflammation.

CONCLUSIONS

Combined IL-4 and IL-13 deficiency is required for protection against TGF-β-induced pulmonary vascular disease after Schistosoma exposure, and targeted inhibition of this pathway is a potential novel therapeutic approach for patients with schistosomiasis-associated PAH.

Novosphingobium and its potential role in chronic obstructive pulmonary diseases: insights from microbiome studies

Bacterial infection of lung airways underlies some of the main complications of COPD, significantly impacting disease progression and outcome. Colonization by bacteria may further synergize, amplify, or trigger pathways of tissue damage started by cigarette smoke, contributing to the characteristic airway inflammation and alveolar destruction of COPD. We sought to elucidate the presence and types of lung bacterial populations in different stages of COPD, aimed at revealing important insights into the pathobiology of the disease. Sequencing of the bacterial small subunit ribosomal RNA gene in 55 well-characterized clinical lung samples, revealed the presence of Novosphingobium spp. (>2% abundance) in lungs of patients with GOLD 3-GOLD 4 COPD, cystic fibrosis and a subset of control individuals. Novosphingobium-specific quantitative PCR was concordant with the sequence data and high levels of Novosphingobium spp. were quantifiable in advanced COPD, but not from other disease stages. Using a mouse model of subacute lung injury due to inhalation of cigarette smoke, bronchoalveolar lavage neutrophil and macrophage counts were significantly higher in mice challenged intratracheally with N. panipatense compared to control mice (p<0.01). Frequencies of neutrophils and macrophages in lung tissue were increased in mice challenged with N. panipatense at room air compared to controls. However, we did not observe an interaction between N. panipatense and subacute cigarette smoke exposure in the mouse. In conclusion, Novosphingobium spp. are present in more severe COPD disease, and increase inflammation in a mouse model of smoke exposure.

Interleukin (IL)-17/IL-22-producing T cells enriched within the liver of patients with chronic hepatitis C viral (HCV) infection

BACKGROUND

Effector CD4+ helper T cells have historically been classified into T helper 1 (Th1) and Th2 based on the production of signature cytokines. The recently identified interleukin (IL)-17 cytokine family plays important roles in host immunity against intracellular pathogens and in chronic inflammatory conditions; data have implicated IL-17 in autoimmune and viral liver disease.

METHODS

This study used three patient groups with HCV infection: acute HCV who either cleared spontaneously or became chronically infected (n = 12), endstage liver disease from whom both peripheral and intrahepatic lymphocytes were studied directly ex vivo (n = 11), and 134 patients with different stages of HCV-related fibrosis from whom serum was collected concurrently with liver biopsy. Normal healthy subjects (n = 41) served as controls.

RESULTS

Acute HCV was not associated with expansion of either CD4+ or CD8+ T cells producing IL-17 (Th17, Tc17) or IL-22, and frequencies did not differ in the blood of patients who cleared versus became persistently infected. The hepatic compartment of chronic HCV patients demonstrated statistically more CD4+ and CD8+ that produced IL-17, IL-22 or both as compared to peripheral blood. These T cells displayed a distinct phenotypic profile, high expression of the homing receptor CD161 and low levels of inhibitory receptors, mucin-domain-containing-molecule-3 (Tim-3) and programmed-death 1. Using a sensitive ELISA, we found no significant differences in serum levels of IL-17 according to HCV-related fibrosis.

CONCLUSIONS

In chronic HCV, T cells producing IL-17/IL-22 may home to the liver; however, circulating levels of IL-17 do not correlate with fibrosis.

Protective interleukin-28B genotype affects hepatitis C virus clearance, but does not contribute to HIV-1 control in a cohort of African-American elite controllers/suppressors

We tested the hypothesis that a single nucleotide polymorphism (SNP) located near the interleukin-28B gene is associated with the control of hepatitis C virus and HIV-1 replication in elite controllers/suppressors. We show here that the protective genotype is not overrepresented in elite controllers/suppressors compared with HIV-1-seronegative patients and HIV-1-infected patients with viral loads more than 10 000 copies/ml. Thus, it appears that this SNP is not associated with the elite control of HIV-1 infection.

High-programmed death-1 levels on hepatitis C virus-specific T cells during acute infection are associated with viral persistence and require preservation of cognate antigen during chronic infection

Hepatitis C virus (HCV) is an important human pathogen that represents a model for chronic infection given that the majority of infected individuals fail to clear the infection despite generation of virus-specific T cell responses during the period of acute infection. Although viral sequence evolution at targeted MHC class I-restricted epitopes represents one mechanism for immune escape in HCV, many targeted epitopes remain intact under circumstances of viral persistence. To explore alternative mechanisms of HCV immune evasion, we analyzed patterns of expression of a major inhibitory receptor on T cells, programmed death-1 (PD-1), from the time of initial infection and correlated these with HCV RNA levels, outcome of infection, and sequence escape within the targeted epitope. We show that the level of PD-1 expression in early HCV infection is significantly higher on HCV-specific T cells from subjects who progress to chronic HCV infection than from those who clear infection. This correlation is independent of HCV RNA levels, compatible with the notion that high PD-1 expression on HCV-specific CD8 T cells during acute infection inhibits viral clearance. Viral escape during persistent infection is associated with reduction in PD-1 levels on the surface of HCV-specific T cells, supporting the necessity of ongoing antigenic stimulation of T cells for maintenance of PD-1 expression. These results support the idea that PD-1 expression on T cells specific for nonescaped epitopes contributes to viral persistence and suggest that PD-1 blockade may alter the outcome of HCV infection.

Hepatitis C virus immune escape via exploitation of a hole in the T cell repertoire

Hepatitis C virus (HCV) infection frequently persists despite eliciting substantial virus-specific immune responses. Thus, HCV infection provides a setting in which to investigate mechanisms of immune escape that allow for viral persistence. Viral amino acid substitutions resulting in decreased MHC binding or impaired Ag processing of T cell epitopes reduce Ag density on the cell surface, permitting evasion of T cell responses in chronic viral infection. Substitutions in viral epitopes that alter TCR contact residues frequently result in escape, but via unclear mechanisms because such substitutions do not reduce surface presentation of peptide-MHC complexes and would be expected to prime T cells with new specificities. We demonstrate that a known in vivo HCV mutation involving a TCR contact residue significantly diminishes T cell recognition and, in contrast to the original sequence, fails to effectively prime naive T cells. This mutant epitope thus escapes de novo immune recognition because there are few highly specific cognate TCR among the primary human T cell repertoire. This example is the first on viral immune escape via exploitation of a "hole" in the T cell repertoire, and may represent an important general mechanism of viral persistence.

Evaluation of aldrithiol-2-inactivated preparations of HIV type 1 subtypes A, B, and D as reagents to monitor T cell responses

The development of HIV vaccines is an urgent priority and there is need to generate reagents representing multiple subtypes that can be used to screen HIV-1-specific responses. We used Aldrithiol-2 (AT-2), a mild oxidizing reagent, to eliminate the infectivity of HIV while maintaining its structure and ability to be processed for presentation to T cells. Inactivated subtype A, B, and D viruses were evaluated for their ability to stimulate T cell responses in PBMC samples from 18 U.S. subjects infected with HIV-1 subtype B and 32 Ugandan subjects infected with subtypes A and D or recombinants AC and AD. Five HIV-1-negative samples were also analyzed. T cell responses to AT-2-inactivated viral isolates were monitored by interferon-gamma (IFN-gamma) intracellular cytokine secretion (ICS) analysis; matched microvesicle preparations served as negative controls. Among the 18 subtype B infected subjects, 39% had CD3(+) CD4 (+) IFN-gamma responses and 67% had CD3(+) CD8(+) IFN-gamma responses. Of the 32 Ugandan subjects, 34% demonstrated CD3(+) CD4(+) IFN-gamma responses and 78% demonstrated CD3(+) CD8(+) IFN-gamma responses. Both subtype-specific and cross-reactive responses were observed. Responses to the AT-2 viruses tended to be lower in magnitude than those detected by a set of overlapping gag peptides. Robust lymphoproliferative responses to AT-2 viruses were seen in a subset of subjects. In conclusion, AT-2-inactivated HIV-1 virions stimulated both CD4 and CD8 HIV-1-specific responses and may provide an additional reagent for screening HIV-1-specific responses in HIV seropositives and vaccinees.

HIV-1 MN Env 15-mer peptides better detect HIV-1 specific CD8 T cell responses compared with consensus subtypes B and M group 15-mer peptides

OBJECTIVE

To compare the ability of three Env (15-mer) peptide sets derived from the HIV-1 MN, the subtype B consensus, and the group M consensus to detect HIV-1 specific interferon (IFN)-gamma responses in HIV-1 subtype B infected subjects.

METHODS

Peripheral blood mononuclear cells were obtained from 17 HIV-1 subtype B seropositive and 5 HIV-1 seronegative subjects. Peptide matrices comprising each peptide set were used in IFN-gamma Elispot assays to screen for T cell epitopes. Following matrix deconvolution, individual peptides were analyzed by IFN-gamma intracellular cytokine-staining to confirm and characterize the responding cells.

RESULTS

HIV specific IFN-gamma responses were detected in 17 of 17 HIV-1 seropositive and none of 5 HIV-1 seronegative subjects by Elispot. Within the 17 HIV-1 seropositives, 16, 14, and 11 subjects responded to MN, B consensus, and group M env peptides, respectively. Responses were confirmed by intracellular cytokine analysis in 14 subjects and were in the CD3CD8 compartment. Cross-recognition of 'equivalent' peptides (i.e., peptides mapping to the same sequence region from the three peptide sets) was observed in 9 of 17 subjects. Peptide set specific responses to individual peptides were also observed; 11, 1, and 1 subjects demonstrated peptide set specific responses to MN, B consensus, and consensus group M, respectively.

CONCLUSION

MN derived Env peptides were better able to detect HIV-1 specific CD8 T cell responses, many of which were not detectable by the equivalent clade or group consensus peptides. No single peptide set detected all the IFN-gamma responses within an individual. These results demonstrate the importance of reagent selection for monitoring of HIV responses in HIV-1 infected individuals and subsequently vaccine recipients.

HIV type 1-specific inter- and intrasubtype cellular immune responses in HIV type 1-infected Ugandans

Investigations concerning the extent and nature of subtype-specific and intersubtype immune responses in HIV-1-infected persons are necessary for the development of appropriate candidate vaccines. In the cross-sectional study described here, 26 HIV-1-positive Ugandan patients were tested for their ability to mount HIV antigen-specific cellular immune responses. Subjects were infected with either HIV-1 subtypes A, C, or D. Recombinant vaccinia virus (rVV)-based and peptide-based enzyme-linked immunospot (Elispot) assays were used to evaluate HIV-1-specific gamma-interferon (IFN-gamma) cellular responses. rVV expressing gag, pol, or env proteins derived from HIV-1 subtypes A, B, and D were evaluated for their ability to induce whole HIV-1-protein-specific IFN-gamma responses in 14 patients. A panel of previously identified HLA class I-restricted peptides based on representative sequences from HIV-1 subtypes A, B, C, and D and restricted through HLA-A2, -A29, -B42, -B53, and -B57 alleles were used to evaluate the presence of HIV-1-peptide-specific T cells in 19 patients. Using rVV, 27 of a possible 38 subtype-specific responses (71%) and 56 of a possible 110 intersubtype responses (51%) were observed. When appropriate peptides were used 18 of 39 (46.2%) subtype-specific and 13 of 39 (33.3%) intersubtype responses were observed. Peptide responses were higher quantitatively than those seen when rVV were used. In 7 patients, both rVV and specific peptides were evaluated; in 3 of 7 individuals, global responses were seen despite a lack of measurable HLA-restricted peptide-specific responses demonstrating the need to evaluate a broader range of HIV-specific immune responses.

Effect of human immunodeficiency virus (HIV) type 1 envelope subtypes A and D on disease progression in a large cohort of HIV-1-positive persons in Uganda

The effect of human immunodeficiency virus (HIV) type 1 envelope subtypes A and D on disease progression was investigated in 1045 adults in Uganda. At enrollment and every 6 months, a clinical history, examination, and laboratory investigations that included CD4 cell counts were done. HIV-1 envelope subtype was assessed mainly by peptide serology supplemented by heteroduplex mobility assay and DNA sequencing. A multivariate analysis of survival was performed to assess the prognostic value of HIV-1 subtype on death. A marginal general linear model also determined the effect of subtype on CD4 cell count during follow-up. Subtype D was associated with faster progression to death (relative risk, 1.29; 95% confidence interval, 1.07-1.56; P=.009) and with a lower CD4 cell count during follow-up (P=.001), compared with subtype A, after adjusting for CD4 cell count at enrollment. In Africa, envelope subtype D is associated with faster disease progression, compared with subtype A.

Comparative loss and maturation of peripheral blood dendritic cell subpopulations in African and non-African HIV-1-infected patients

OBJECTIVES

To quantify the percentage of the two major subpopulations of blood dendritic cells (DC) in HIV-1-seropositive Ugandan individuals infected with non-clade B viruses and compare this with that seen in clade B HIV-1 infected non-African individuals. DC maturation/activation status was also investigated via the expression of CD86.

METHODS

The percentage of blood DC was quantified by using flow cytometry. DC were identified as the lineage (CD3, CD14, CD16, CD19, CD20, CD56)-negative, HLA-DR-positive population and the two major subpopulations were differentiated by CD11c expression.

RESULTS

The percentage of blood DC was reduced significantly in HIV-1-seropositive African individuals when compared with controls (0.21 and 0.39% respectively). A similar reduction was also seen in non-African patients residing in the UK (0.19% compared with 0.36% for controls). However, there was no selective loss in either CD11c-positive or CD11c-negative subpopulations. The percentage of blood DC expressing CD86 was significantly greater in HIV-1-seropositive individuals when compared with controls and the increased expression was largely confined to CD11c-negative DC.

CONCLUSIONS

Africans infected with non-clade B HIV-1 showed similar reductions in the percentage of blood DC to non-Africans infected with clade B viruses. There was no selective loss of either DC subpopulation, suggesting that the ability of DC to acquire and present antigens or to produce interferon-alpha may both be impaired in HIV-1 infection.

Relationship between HIV-1 Env subtypes A and D and disease progression in a rural Ugandan cohort

OBJECTIVE

To investigate the role of HIV-1 envelope subtypes on disease progression in a rural cohort of Ugandan adults where two major HIV-1 subtypes (A and D) exist.

METHODS

Participants of a clinical cohort seen between December 1995 and December 1998 had blood collected for HIV-1 subtyping. These included prevalent cases (people already infected with HIV at the start of the study in 1990) and incident cases (those who seroconverted between 1990 and December 1998). HIV-1 subtyping was carried out by heteroduplex mobility assay and DNA sequencing in the V3 env region. Disease progression was measured by the rate of CD4 lymphocyte count decline, clinical progression for the incident cases as time from seroconversion to AIDS or death, to first CD4 lymphocyte count < 200 x 10(6)/l and to the World Health Organization clinical stage 3. All analyses were adjusted for age and sex.

RESULTS

One hundred and sixty-four individuals, including 47 prevalent and 117 incident cases, had V3 env subtype data of which 65 (40%) were subtyped as A and 99 as D. In the incident cases, 44 (38%) were subtyped as A and 73 as D. There was a suggestion that for most end-points A had a slower progression than D. The cumulative probability of remaining free from AIDS or death at 6 years post-seroconversion was 0.72 [95% confidence interval (CI), 0.50 to 0.85] for A and 0.58 (95% CI, 0.42 to 0.71) for D, and the adjusted hazard ratio of subtype D compared to A was estimated to be 1.39 (95% CI, 0.66 to 2.94; P = 0.39). The estimated difference in rates of decline in square root CD4 lymphocyte counts was -0.41 per year (95% CI, -0.98 to 0.15; P = 0.15).

CONCLUSION

This study suggests that although subtype A may have a slower progression than D, HIV-1 envelope subtype is not a major factor in determining the progression of HIV-1 disease in a rural population in Uganda.

The stability between two HIV-1 RNA measurements one year apart and the relationship with HIV subtype in rural Uganda

We compared HIV-1 RNA levels using the nucleic acid sequenced based amplification (NASBA) test kit in 2 samples taken one year apart from participants infected with env subtype A or D in a population-based cohort in Uganda. Fifty participants were infected with subtype A and 70 with subtype D. HIV-1 RNA levels were significantly higher in subtype D unadjusted (P=0.001), and after adjusting for age, gender, and CD4 count (P<0.001). Eighty-six participants had HIV-1 RNA measurements in both years and 67 (78%) were within one log10 of their result a year before. There was no relationship between the difference in log viral load and proportion of CD4 change. Individuals infected with subtype D had a higher average increase in viral load and this was statistically significant if adjusted for baseline levels and CD4 count (P=0.015).

Vaccines for the control of HIV/AIDS

This review discusses the feasibility of an HIV vaccine and describes the history, efficacy and potential to succeed of old and new vaccine concepts.

An improved algorithm for determining HIV type 1 subtypes in a primary laboratory in Uganda

A pilot study was undertaken with the objective of developing a simple, economical, and efficient algorithm through which to subtype HIV-1 in a large epidemiological cohort study in Uganda. A peptide enzyme immunoassay (PEIA) employing both V3 and gp41 regions and a heteroduplex mobility assay (HMA) were evaluated in comparison with DNA sequencing. Of 146 samples selected, 115 (79%) were successfully sequenced. Taking sequence data as the "gold standard," other assays were compared with these data. The HMA correctly identified 95 (83%) of the samples, and only 1 sample was wrongly identified. The V3 PEIA alone and in combination with gp41 peptides correctly identified 76 and 78% of the samples, respectively; however, the number of wrongly identified samples was four times less with the combination compared with V3 peptides alone (4 versus 16%). The sensitivity, specificity, and positive and negative predictive values for serotype A and D samples were greater for the combination than V3 peptides alone. We have described a new algorithm to segregate subtypes A and D. This algorithm uses the two peptide assays followed by HMA and then DNA sequencing for untypable samples, giving an accuracy of 95% at a cost of 37 and 21% for consumables compared with subtyping all the samples by HMA or DNA sequencing, respectively. This proposed approach is suitable for epidemiological studies in Uganda and other regions with a predominance of A and D subtypes.

Molecular epidemiology of HIV type 1 in a rural community in southwest Uganda

The molecular epidemiology of a population-based cohort in a cluster of 15 villages in southwestern Uganda was investigated by sequencing part of the p24 gag gene and performing heteroduplex mobility assays (HMAs) of the V3 region of the env gene. Sequence and HMA data, obtained for 69 and 88 proviruses, respectively, showed that the clade A and D viruses were present at a ratio of about 0.67:1. No other clades were detected. Thirteen (22%) of 59 proviruses for which both gag and env data were obtained appeared to be recombinants. Although both clade A and D viruses were present in 13 of the villages, their distribution was unequal: for example, from env data 59% of clade A viruses were found in the eastern villages, compared with only 27% of clade D viruses. Phylogenetic (maximum likelihood) analysis of the p24 gag sequences showed a total of five clusters supported by bootstrap resampling values above or close to 75%. Four clusters were sexual partners, but there was no known sexual contact between the persons in the other cluster. The DNA sequences showed between 0.5 and 8.3% divergence from the cohort clade A or D consensus sequences. The sequences were not closely related to those published for other clade A or D proviruses.

HIV-1 RNA levels in an African population-based cohort and their relation to CD4 lymphocyte counts and World Health Organization clinical staging

Apart from a small number of reports from people who are based in hospitals, data on viral load in HIV-infected people in sub-Saharan Africa, where most infections occur, are lacking. We report serum HIV-1 RNA levels in a population-based cohort in rural Uganda using the nucleic acid sequence-based amplification procedure (NASBA) test kit and describe their relation to CD4 counts and World Health Organization (WHO) clinical staging. The median (interquartile range [IQR]) viral loads were 87,000 copies/ml (37,500-295,000 copies/ml) in 40 prevalent cases infected for >6 years, and 31,000 copies/ml (7800-174,000 copies/ml) in 65 incident cases with seroconversion dates within the previous 6 years. Although we found a correlation between viral load and absolute CD4 count (p < .0001), there was no evidence for an association with CD4 decline (p = .1). Overall, there was a significant trend of increasing viral load with worsening clinical stage from a median viral load of 15,000 for those in WHO stage 1 (asymptomatic) to 150,600 copies/ml for those in stage 4 (AIDS; p < .001). However, the association was seen only in incident cases. Thus, we found that the NASBA test on serum was a useful indicator of disease stage especially in persons known to be infected for <6 years. Such baseline data are important for vaccine research, and if antiretroviral drugs become available to more than a few people in Africa, it will be important that accurate viral load estimations are available at least in a proportion of people to monitor the effectiveness of treatment, and measure the compliance and emerging resistance to these drugs.