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1.
Open Forum Infect Dis ; 11(1): ofad623, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38192382

RESUMO

We aimed to evaluate the effect of hepatitis C virus cure on serum inflammatory markers among people with HIV. Among 127 people with HIV, serum alanine aminotransferase, soluble tumor necrosis factor receptor 1, and inflammatory index score were significantly lower at the 24-week time point in patients who achieved sustained virologic response as compared with those who did not.

2.
Curr Top Microbiol Immunol ; 441: 61-73, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37695425

RESUMO

Biological sex has wide-ranging impacts on HIV infection spanning differences in acquisition risk, the pathogenesis of untreated infection, impact of chronic treated disease and prospects for HIV eradication or functional cure. This chapter summarizes the scope of these differences and discusses several features of the immune response thought to contribute to the clinical outcomes.


Assuntos
Infecções por HIV , Caracteres Sexuais , Feminino , Masculino , Humanos
3.
J Clin Invest ; 133(21)2023 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-37698927

RESUMO

BACKGROUNDHIV-1-infected CD4+ T cells contribute to latent reservoir persistence by proliferating while avoiding immune recognition. Integration features of intact proviruses in elite controllers (ECs) and people on long-term therapy suggest that proviruses in specific chromosomal locations can evade immune surveillance. However, direct evidence of this mechanism is missing.METHODSIn this case report, we characterized integration sites and full genome sequences of expanded T cell clones in an EC before and after chemoradiation. We identified the cognate peptide of infected clones to investigate cell proliferation and virus production induced by T cell activation, and susceptibility to autologous CD8+ T cells.RESULTSThe proviral landscape was dominated by 2 large clones with replication-competent proviruses integrated into zinc finger (ZNF) genes (ZNF470 and ZNF721) in locations previously associated with deeper latency. A third nearly intact provirus, with a stop codon in Pol, was integrated into an intergenic site. Upon stimulation with cognate Gag peptides, infected clones proliferated extensively and produced virus, but the provirus in ZNF721 was 200-fold less inducible. While autologous CD8+ T cells decreased the proliferation of cells carrying the intergenic provirus, they had no effect on cells with the provirus in the ZNF721 gene.CONCLUSIONSWe provide direct evidence that upon activation of infected clones by cognate antigen, the lower inducibility of intact proviruses in ZNF genes can result in immune evasion and persistence.FUNDINGOffice of the NIH Director and National Institute of Dental & Craniofacial Research; NIAID, NIH; Johns Hopkins University Center for AIDS Research.


Assuntos
Infecções por HIV , HIV-1 , Humanos , Provírus/genética , Linfócitos T CD4-Positivos , Células Clonais , Latência Viral
4.
HIV Res Clin Pract ; 24(1): 2246717, 2023 08 08.
Artigo em Inglês | MEDLINE | ID: mdl-37608645

RESUMO

BACKGROUND: Cisgender women represent over half of people living with HIV globally. However, current research efforts toward a cure for HIV focus predominantly on cisgender men. The under-representation of women in HIV cure clinical studies is particularly problematic given data suggesting that sex-dependent phenotypes limit scientific discovery. OBJECTIVE: We aimed to generate considerations to increase the meaningful involvement of women in HIV cure-related research. MATERIALS AND METHODS: We conducted in-depth interviews with biomedical researchers and community members to better understand factors that could increase the meaningful involvement of women in HIV cure clinical trials. Participants were affiliated with academia, industry, community advisory boards, and community-based organizations, and were identified using listings from the AIDS Clinical Trials Group and the Martin Delaney Collaboratories. We used conventional content analysis to analyze the qualitative data. RESULTS: We recruited 27 participants, of whom 11 were biomedical researchers and 16 were community members. Participants included 25 cisgender women, 1 transgender woman, and 1 cisgender man. Key considerations emerged, including the need to ensure that HIV cure studies reflect HIV epidemiologic trends and having accurate representation by sex and gender in HIV cure research. To increase the meaningful involvement of women, recommendations included instituting intentional enrollment goals, frequent and mandatory reporting on enrollment, and incentives for sites to enroll women. Additional themes included the need for agency and self-determination, attention to lived experiences, trauma and healing, and adequate support for women (e.g. logistical, psychosocial, mental, emotional, and physical). Participants noted that women would be willing to participate in HIV cure trials, related procedures (e.g. biopsies), and analytical treatment interruptions. They also expressed a desired for women-centered and holistic clinical trial designs that account for intersectionality. CONCLUSIONS: Our empirical inquiry extends recent calls to action to increase diversity of people involved in HIV cure research. Redressing the under-inclusion of women in HIV cure research is an urgent imperative. The entire field must mobilize and reform to achieve this goal. Meaningfully involving women across the gender spectrum in HIV cure research is needed to ensure that interventions are safe, effective, scalable, and acceptable for all people with HIV.


Assuntos
Academias e Institutos , Infecções por HIV , Feminino , Humanos , Masculino , Estados Unidos/epidemiologia , Pesquisa Qualitativa , Pesquisa Empírica , Biópsia , Infecções por HIV/tratamento farmacológico , Infecções por HIV/epidemiologia
5.
JCI Insight ; 8(11)2023 06 08.
Artigo em Inglês | MEDLINE | ID: mdl-37097752

RESUMO

Biological sex and host genetics influence HIV pathogenesis. Females have a higher likelihood of spontaneous viral control and lower set point viral load (spVL). No prior studies have assessed sex-specific genetics of HIV. To address this, we performed a sex-stratified genome-wide association study using data from the ICGH. Although it is the largest collection of genomic data in HIV, this multiethnic sample of 9,705 people is 81.3% male. We sought to identify sex-specific genetic variants and genes associated with HIV spVL and control. We confirmed associations in the HLA and CCR5 regions in males and HLA in females. Gene-based analyses detected associations between HIV spVL and PET100, PCP2, XAB2, and STXBP2 only in males. We detected variants with a significant sex-differential effect on spVL in SDC3 and PUM1 (rs10914268) and PSORS1C2 (rs1265159) and on HIV control in SUB1 (rs687659), AL158151.3, PTPA, and IER5L (rs4387067). Those variants have epigenetic and genetic interactions with relevant genes with both cis and trans effects. In summary, we identified sex-shared associations at the single-variant level, sex-specific associations at the gene-based level, and genetic variants with significant differential effects between the sexes.


Assuntos
Infecções por HIV , HIV-1 , Feminino , Humanos , Masculino , Infecções por HIV/genética , HIV-1/genética , Carga Viral/genética , Estudo de Associação Genômica Ampla , Genômica , Proteínas de Ligação a RNA/genética
8.
Clin Infect Dis ; 75(8): 1389-1396, 2022 10 12.
Artigo em Inglês | MEDLINE | ID: mdl-35176755

RESUMO

BACKGROUND: Biological sex and the estrogen receptor alpha (ESR1) modulate human immunodeficiency virus (HIV) activity. Few women have enrolled in clinical trials of latency reversal agents (LRAs); their effectiveness in women is unknown. We hypothesized that ESR1 antagonism would augment induction of HIV expression by the LRA vorinostat. METHODS: AIDS Clinical Trials Group A5366 enrolled 31 virologically suppressed, postmenopausal women on antiretroviral therapy. Participants were randomized 2:1 to receive tamoxifen (arm A, TAMOX/VOR) or observation (arm B, VOR) for 5 weeks followed by 2 doses of vorinostat. Primary end points were safety and the difference between arms in HIV RNA induction after vorinostat. Secondary analyses included histone 4 acetylation, HIV DNA, and plasma viremia by single copy assay (SCA). RESULTS: No significant adverse events were attributed to study treatments. Tamoxifen did not enhance vorinostat-induced HIV transcription (between-arm ratio, 0.8; 95% confidence interval [CI], .2-2.4). Vorinostat-induced HIV transcription was higher in participants with increases in H4Ac (fold increase, 2.78; 95% CI, 1.34-5.79) vs those 9 who did not (fold increase, 1.04; 95% CI, .25-4.29). HIV DNA and SCA plasma viremia did not substantially change. CONCLUSIONS: Tamoxifen did not augment vorinostat-induced HIV RNA expression in postmenopausal women. The modest latency reversal activity of vorinostat, postmenopausal status, and low level of HIV RNA expression near the limits of quantification limited assessment of the impact of tamoxifen. This study is the first HIV cure trial done exclusively in women and establishes both the feasibility and necessity of investigating novel HIV cure strategies in women living with HIV. CLINICAL TRIALS REGISTRATION: NCT03382834.


Assuntos
Síndrome da Imunodeficiência Adquirida , Infecções por HIV , HIV-1 , Síndrome da Imunodeficiência Adquirida/tratamento farmacológico , Linfócitos T CD4-Positivos , DNA/uso terapêutico , Receptor alfa de Estrogênio/metabolismo , Feminino , HIV-1/genética , Inibidores de Histona Desacetilases/metabolismo , Inibidores de Histona Desacetilases/farmacologia , Inibidores de Histona Desacetilases/uso terapêutico , Histonas/metabolismo , Histonas/uso terapêutico , Humanos , RNA/metabolismo , RNA/uso terapêutico , Tamoxifeno/efeitos adversos , Tamoxifeno/metabolismo , Viremia/tratamento farmacológico , Latência Viral , Vorinostat/metabolismo , Vorinostat/farmacologia , Vorinostat/uso terapêutico
9.
Clin Infect Dis ; 75(1): 73-80, 2022 08 24.
Artigo em Inglês | MEDLINE | ID: mdl-34612493

RESUMO

BACKGROUND: Sex differences in human immunodeficiency virus (HIV) reservoir dynamics remain underexplored. METHODS: Longitudinal samples from virally suppressed midlife women (n = 59, median age 45 years) and age-matched men (n = 31) were analyzed retrospectively. At each time point, we measured sex hormones (by means of enzyme-linked immunosorbent assay) and cellular HIV DNA and RNA (by means of digital droplet polymerase chain reaction). Number of inducible HIV RNA+ cells, which provides an upper estimate of the replication-competent reservoir, was quantified longitudinally in a different subset of 14 women, across well-defined reproductive stages. Mixed-effects models included normalized reservoir outcomes and sex, time since antiretroviral therapy (ART) initiation, and the sex-by-time interaction as predictors. RESULTS: At ART initiation, women and men had median (interquartile range [IQR]) CD4+ T-cell counts of 204/µL (83-306/µL) versus 238/µL (120-284/µL), respectively; median ages of 45 (42-48) versus 47 (43-51) years; and median follow-up times of 79.2/µL (60.5-121.1/µL) versus 66.2/µL (43.2-80.6/µL) months. We observed a significant decline of total HIV DNA over time in both men and women (P < .01). However, the rates of change differed significantly between the sexes (P < .01), with women having a significantly slower rate of decline than men, more pronounced with age. By contrast, the levels of inducible HIV RNA increased incrementally over time in women during reproductive aging (P < .01). CONCLUSIONS: In contrast to men, in whom the HIV reservoir steadily declines with aging, the HIV reservoir in women is more dynamic. Total HIV DNA (including intact and defective genomes) declines more slowly in women than in men, while the inducible HIV RNA+ reservoir, which is highly enriched in replication-competent virus, increases in women after menopause.


Assuntos
Infecções por HIV , Caracteres Sexuais , Envelhecimento , Linfócitos T CD4-Positivos , Feminino , HIV , Infecções por HIV/tratamento farmacológico , Infecções por HIV/epidemiologia , Humanos , Masculino , Pessoa de Meia-Idade , RNA , Estudos Retrospectivos , Carga Viral
10.
J Clin Invest ; 131(22)2021 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-34779416

RESUMO

HIV and Mycobacterium tuberculosis (M. tuberculosis) coinfection increases the risk of active tuberculosis (aTB), but how HIV infection and medications contribute to drive risk remains unknown. In this issue of the JCI, Correa-Macedo and Fava et al. investigated alveolar macrophages (AMs) from people living with HIV (PLWH). To mimic the earliest event in tuberculosis (TB), the authors isolated AMs from broncheoalveolar lavage (BAL) of PLWH, healthy individuals, and healthy individuals taking antitretroviral therapy (ART) as preexposure prophylaxis (PrEP) to prevent HIV acquisition. These AMs were exposed to M. tuberculosis and epigenetic configuration, transcriptional responses, and cytokine production were assessed. M. tuberculosis-stimulated AMs from PLWH and from healthy individuals on PrEP showed blunted responses compared with healthy controls. While HIV infection is the major risk factor for TB, these findings suggest that ART may modulate AM responses and potentially contribute to residual risk of aTB in fully treated HIV.


Assuntos
Coinfecção , Infecções por HIV , Mycobacterium tuberculosis , Tuberculose , Infecções por HIV/complicações , Infecções por HIV/tratamento farmacológico , Humanos , Macrófagos Alveolares , Tuberculose/tratamento farmacológico , Tuberculose/epidemiologia
11.
Open Forum Infect Dis ; 8(9): ofab448, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34584899

RESUMO

BACKGROUND: Males experience increased severity of illness and mortality from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) compared with females, but the mechanisms of male susceptibility are unclear. METHODS: We performed a retrospective cohort analysis of SARS-CoV-2 testing and admission data at 5 hospitals in the Maryland/Washington DC area. Using age-stratified logistic regression models, we quantified the impact of male sex on the risk of the composite outcome of severe disease or death (World Health Organization score 5-8) and tested the impact of demographics, comorbidities, health behaviors, and laboratory inflammatory markers on the sex effect. RESULTS: Among 213 175 SARS-CoV-2 tests, despite similar positivity rates, males in age strata between 18 and 74 years were more frequently hospitalized. For the 2626 hospitalized individuals, clinical inflammatory markers (interleukin-6, C-reactive protein, ferritin, absolute lymphocyte count, and neutrophil:lymphocyte ratio) were more favorable for females than males (P < .001). Among 18-49-year-olds, male sex carried a higher risk of severe outcomes, both early (odds ratio [OR], 3.01; 95% CI, 1.75 to 5.18) and at peak illness during hospitalization (OR, 2.58; 95% CI, 1.78 to 3.74). Despite multiple differences in demographics, presentation features, comorbidities, and health behaviors, these variables did not change the association of male sex with severe disease. Only clinical inflammatory marker values modified the sex effect, reducing the OR for severe outcomes in males aged 18-49 years to 1.81 (95% CI, 1.00 to 3.26) early and 1.39 (95% CI, 0.93 to 2.08) at peak illness. CONCLUSIONS: Higher inflammatory laboratory test values were associated with increased risk of severe coronavirus disease 2019 for males. A sex-specific inflammatory response to SARS-CoV-2 infection may underlie the sex differences in outcomes.

12.
medRxiv ; 2021 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-33851190

RESUMO

BACKGROUND: Rates of severe illness and mortality from SARS-CoV-2 are greater for males, but the mechanisms for this difference are unclear. Understanding the differences in outcomes between males and females across the age spectrum will guide both public health and biomedical interventions. METHODS: Retrospective cohort analysis of SARS-CoV-2 testing and admission data in a health system. Patient-level data were assessed with descriptive statistics and logistic regression modeling was used to identify features associated with increased male risk of severe outcomes. RESULTS: In 213,175 SARS-CoV-2 tests, despite similar positivity rates (8.2%F vs 8.9%M), males were more frequently hospitalized (28%F vs 33%M). Of 2,626 hospitalized individuals, females had less severe presenting respiratory parameters and males had more fever. Comorbidity burden was similar, but with differences in specific conditions. Medications relevant for SARS-CoV-2 were used at similar frequency except tocilizumab (M>F). Males had higher inflammatory lab values. In a logistic regression model, male sex was associated with a higher risk of severe outcomes at 24 hours (odds ratio (OR) 3.01, 95%CI 1.75, 5.18) and at peak status (OR 2.58, 95%CI 1.78,3.74) among 18-49 year-olds. Block-wise addition of potential explanatory variables demonstrated that only the inflammatory labs substantially modified the OR associated with male sex across all ages. CONCLUSION: Higher levels of clinical inflammatory labs are the only features that are associated with the heightened risk of severe outcomes and death for males in COVID-19. TRIAL REGISTRATION: NA. FUNDING: Hopkins inHealth; COVID-19 Administrative Supplement (HHS Region 3 Treatment Center), Office of the ASPR; NIH/NCI U54CA260492 (SK), NIH/NIA U54AG062333 (SK).

14.
Curr Opin HIV AIDS ; 16(1): 48-53, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33278160

RESUMO

PURPOSE OF REVIEW: The global pandemic caused by the severe acute respiratory virus coronavirus 2 (SARS-CoV-2) has a male bias in mortality likely driven by both gender and sex-based differences between male and female individuals. This is consistent with sex and gender-based features of HIV infection and overlap between the two diseases will highlight potential mechanistic pathways of disease and guide research questions and policy interventions. In this review, the emerging findings from SARS-CoV-2 infection will be placed in the context of sex and gender research in the more mature HIV epidemic. RECENT FINDINGS: This review will focus on the new field of literature on prevention, immunopathogenesis and treatment of SARS-CoV-2 referencing relevant articles in HIV for context from a broader time period, consistent with the evolving understanding of sex and gender in HIV infection. Sex-specific features of epidemiology and immunopathogenesis reported in COVID-19 disease will be discussed and potential sex and gender-specific factors of relevance to prevention and treatment will be emphasized. SUMMARY: Multilayered impacts of sex and gender on HIV infection have illuminated pathways of disease and identified important goals for public health interventions. SARS-CoV-2 has strong evidence for a male bias in disease severity and exploring that difference will yield important insights.


Assuntos
COVID-19/virologia , SARS-CoV-2/fisiologia , Animais , COVID-19/epidemiologia , Feminino , HIV/genética , HIV/fisiologia , Infecções por HIV/virologia , Humanos , Masculino , Pandemias , SARS-CoV-2/genética , Fatores Sexuais
15.
Cell Rep ; 33(11): 108502, 2020 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-33326789

RESUMO

Changes in antibody glycosylation are linked to inflammation across several diseases. Alterations in bulk antibody galactosylation can predict rheumatic flares, act as a sensor for immune activation, predict gastric cancer relapse, track with biological age, shift with vaccination, change with HIV reservoir size on therapy, and decrease in HIV and HCV infections. However, whether changes in antibody Fc biology also track with reservoir rebound time remains unclear. The identification of a biomarker that could forecast viral rebound time could significantly accelerate the downselection and iterative improvement of promising HIV viral eradication strategies. Using a comprehensive antibody Fc-profiling approach, the level of HIV-specific antibody Fc N-galactosylation is significantly associated with time to rebound after treatment discontinuation across three independent cohorts. Thus virus-specific antibody glycosylation may represent a promising, simply measured marker to track reservoir reactivation.


Assuntos
Anticorpos Anti-HIV/metabolismo , Carga Viral/métodos , Glicosilação , Humanos
16.
Nat Rev Immunol ; 20(7): 442-447, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32528136

RESUMO

A male bias in mortality has emerged in the COVID-19 pandemic, which is consistent with the pathogenesis of other viral infections. Biological sex differences may manifest themselves in susceptibility to infection, early pathogenesis, innate viral control, adaptive immune responses or the balance of inflammation and tissue repair in the resolution of infection. We discuss available sex-disaggregated epidemiological data from the COVID-19 pandemic, introduce sex-differential features of immunity and highlight potential sex differences underlying COVID-19 severity. We propose that sex differences in immunopathogenesis will inform mechanisms of COVID-19, identify points for therapeutic intervention and improve vaccine design and increase vaccine efficacy.


Assuntos
Infecções por Coronavirus/epidemiologia , Pneumonia Viral/epidemiologia , Imunidade Adaptativa , Fatores Etários , Betacoronavirus/fisiologia , COVID-19 , Infecções por Coronavirus/imunologia , Infecções por Coronavirus/patologia , Infecções por Coronavirus/fisiopatologia , Feminino , Humanos , Interferons/imunologia , Masculino , Pandemias , Pneumonia Viral/imunologia , Pneumonia Viral/patologia , Pneumonia Viral/fisiopatologia , SARS-CoV-2 , Índice de Gravidade de Doença , Fatores Sexuais , Fatores Sociológicos
17.
JCI Insight ; 5(14)2020 07 23.
Artigo em Inglês | MEDLINE | ID: mdl-32544096

RESUMO

HIV-1 infection remains incurable owing to the persistence of a viral reservoir that harbors integrated provirus within host cellular DNA. Increasing evidence links sex-based differences in HIV-1 immune responses and pathogenesis; however, little is known about differences in HIV-1 infection persistence. Here, we quantified persistent HIV-1 infection in 90 adults on suppressive antiretroviral therapy in Rakai, Uganda (57 female patients). Total HIV-1 DNA was quantified by PCR, and replication-competent provirus by quantitative viral outgrowth assay (QVOA). Immune phenotyping of T cell subsets and plasma biomarkers was also performed. We found that whereas both sexes had similar total HIV DNA levels, female patients had significantly fewer resting CD4+ T cells harboring replication-competent virus, as measured by viral outgrowth in the QVOA. Factors associated with viral outgrowth differed by sex; notably, frequency of programmed cell death 1 (PD1+) CD4+ T cells correlated with reservoir size in male but not female patients. The sex-based differences in HIV-1 persistence observed in this cohort warrant additional research, especially given the widespread use of the QVOA to assess reservoir size and current explorations of PD1 agonists in cure protocols. Efforts should be made to power future cure studies to assess outcomes in both male and female patients.


Assuntos
Reservatórios de Doenças/virologia , Infecções por HIV/imunologia , HIV-1/genética , Carga Viral/imunologia , Adulto , Fármacos Anti-HIV/administração & dosagem , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD4-Positivos/virologia , Feminino , Infecções por HIV/tratamento farmacológico , Infecções por HIV/genética , Infecções por HIV/virologia , HIV-1/patogenicidade , Humanos , Masculino , Caracteres Sexuais , Uganda/epidemiologia , Carga Viral/efeitos dos fármacos , Latência Viral/efeitos dos fármacos , Latência Viral/imunologia , Replicação Viral/efeitos dos fármacos , Replicação Viral/imunologia
18.
AIDS Res Hum Retroviruses ; 36(4): 268-282, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32160755

RESUMO

Women remain underrepresented in HIV research. The AIDS Clinical Trials Group (ACTG) 5366 study was the first HIV cure-related trial conducted exclusively in women. Our multidisciplinary team integrated participant-centered reports into the ACTG 5366 protocol to elicit their perspectives. We nested mixed-methods surveys at the enrollment and final study visits to assess ACTG 5366 participants' perceptions and experiences. Of 31 participants enrolled in the ACTG 5366, 29 study agreed to complete the entry questionnaire and 27 completed the exit survey. The majority of study participants were nonwhite. We identified societal and personal motivators for participation, understanding of risks and benefits, and minor misconceptions among some trial participants. Stigma was pervasive for several women who joined the study, and served as a motivator for study participation. Reimbursements to defray costs of study participation were reported to facilitate involvement in the trial by about one-third of participants. Almost all respondents reported positive experiences participating in the ACTG 5366 trial. The ACTG 5366 study showed that it is possible to recruit and retain women in HIV cure-related research and to embed participant-centered outcomes at strategic time points during the study. The findings could help in the design, implementation, recruitment, and retention of women in HIV cure-related research and highlight the value of assessing psychosocial factors in HIV cure-related research participation.


Assuntos
Infecções por HIV/psicologia , Participação do Paciente/psicologia , Inquéritos e Questionários , Fármacos Anti-HIV/uso terapêutico , Feminino , Infecções por HIV/tratamento farmacológico , Humanos , Pesquisa Qualitativa , Medição de Risco , Estigma Social , Tamoxifeno/uso terapêutico , Estados Unidos , Vorinostat/uso terapêutico
19.
J Virus Erad ; 5(3): 167-173, 2019 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-31700665

RESUMO

Observational and interventional studies for HIV cure research often use single-copy assays to quantify rare entities in blood or tissue samples. Statistical analysis of such measurements presents challenges due to tissue sampling variability and frequent findings of 0 copies in the sample analysed. We examined four approaches to analysing such studies, reflecting different ways of handling observations of 0 copies: (A) replace observations of 0 copies with 1 copy; (B) add 1 to all observed numbers of copies; (C) treat observations of 0 copies as left-censored at 1 copy; and (D) leave the data unaltered and apply a method for count data, negative binomial regression. Because research seeks to estimate general patterns rather than individuals' values, we argue that unaltered use of 0 copies is suitable for research purposes and that altering those observations can introduce bias. When applied to a simulated study comparing preintervention to postintervention measurements within 12 participants, methods A-C showed more attenuation than method D in the estimated intervention effect, less chance of finding P < 0.05 for the intervention effect and a lower chance of including the true intervention effect within the 95% confidence interval. Application of the methods to actual data from a study comparing multiply-spliced HIV RNA among men and women estimated smaller differences by methods A-C than by method D. We recommend that negative binomial regression, which is readily available in many statistical software packages, be considered for analysis of studies of rare entities that are measured by single-copy assays.

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