1048. Biological Determinants of Post-Acute Sequelae of SARS-CoV-2

Background

The biological determinants of post-acute sequelae of SARS-CoV-2 infection (PASC), defined as the persistence or recurrence of symptoms not explained by an alternative medical diagnosis, are poorly understood. We assessed viral and immunological determinants during acute SARS-CoV-2 infection for an association with PASC at 4 to 8 months.

Methods

From September 2020 to February 2022, symptomatic non-hospitalized individuals with laboratory-confirmed SARS-CoV-2 infection were identified within 5 days of symptom onset. We used anterior nasal biospecimens to measure the magnitude and duration of RNA and infectious viral shedding as well as blood samples to measure soluble markers of inflammation during the acute phase (first 28 days post-enrollment). PASC was defined as self-report of 1 or more COVID-19 attributed symptoms between 4 and 8 months after initial illness. We compared virologic and inflammatory markers, GFAP (a marker of neuronal damage) and neutralizing antibody levels from the acute phase between those with and without PASC using Mann-Whitney U tests or repeated measures mixed effects linear models.

Results

Among 71 SARS-CoV-2-positive participants with a completed follow-up visit between 4 to 8 months, we included 69 with virologic data and 61 with inflammatory marker data. Median age was 37 (IQR: 29 to 48) Overall, 16/72 (23%) reported at least one qualifying PASC symptom. Report of PASC was associated with >9 days of RNA shedding (p=0.04); all participants stopped RNA shedding by day 20. During acute illness, those with subsequent PASC had increased levelsof INF-alpha, INF-gamma, IP-10, IL-10, and MCP-1; these differences were greatest in the early period and normalized over 2 to 3 weeks post-illness onset. Compared to those without PASC, during the acute illness those with PASC had increased levels of GFAP and decreased levels of neutralizing antibodies but these differences were not statistically significant.

Conclusion

We found indications that viral and immunological factors during acute illness may be associated with PASC, suggesting acute immunologic response to SARS-CoV-2 may have longer term effects and play a role in PASC. Further understanding of the clinically significance of these observations is needed.

Disclosures

Ahmed Chenna, PhD, LabCorp: Employee John Winslow, PhD, Labcorp-Monogram Bioscience: Issued patents on VeraTag immunoassay-not applicable to present work|Labcorp-Monogram Bioscience: Employee|Labcorp-Monogram Biosciences: Issued patents on VeraTag immunoassay-not applicable to present work|Labcorp-Monogram Biosciences: Employee of Labcorp-Monogram Biosciences Christos J. Petropoulos, PhD, Labcorp-Monogram Biosciences: employee, corporate officer|Labcorp-Monogram Biosciences: Stocks/Bonds.

Impact of Tamoxifen on Vorinostat-Induced Human Immunodeficiency Virus Expression in Women on Antiretroviral Therapy: AIDS Clinical Trials Group A5366, The MOXIE Trial

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.

Mitigation strategies to safely conduct HIV treatment research in the context of COVID-19

INTRODUCTION

The International AIDS Society convened a multidisciplinary committee of experts in December 2020 to provide guidance and key considerations for the safe and ethical management of clinical trials involving people living with HIV (PLWH) during the SARS-CoV-2 pandemic. This consultation did not discuss guidance for the design of prevention studies for people at risk of HIV acquisition, nor for the programmatic delivery of antiretroviral therapy (ART).

DISCUSSION

There is strong ambition to continue with HIV research from both PLWH and the research community despite the ongoing SARS-CoV-2 pandemic. How to do this safely and justly remains a critical debate. The SARS-CoV-2 pandemic continues to be highly dynamic. It is expected that with the emergence of effective SARS-CoV-2 prevention and treatment strategies, the risk to PLWH in clinical trials will decline over time. However, with the emergence of more contagious and potentially pathogenic SARS-CoV-2 variants, the effectiveness of current prevention and treatment strategies may be compromised. Uncertainty exists about how equally SARS-CoV-2 prevention and treatment strategies will be available globally, particularly for marginalized populations, many of whom are at high risk of reduced access to ART and/or HIV disease progression. All of these factors must be taken into account when deciding on the feasibility and safety of developing and implementing HIV research.

CONCLUSIONS

It can be assumed for the foreseeable future that SARS-CoV-2 will persist and continue to pose challenges to conducting clinical research in PLWH. Guidelines regarding how best to implement HIV treatment studies will evolve accordingly. The risks and benefits of performing an HIV clinical trial must be carefully evaluated in the local context on an ongoing basis. With this document, we hope to provide a broad guidance that should remain viable and relevant even as the nature of the pandemic continues to develop.

LB8. Lower SARS-CoV-2 IgG and Pseudovirus Neutralization Titers Post-mRNA Vaccination among People Living with HIV

Background

Limited data are available on whether there are differences in the immune response to SARS-CoV-2 vaccination by HIV status or by mRNA vaccine type.

Methods

We saved residual outpatient laboratory samples of all previously mRNA-vaccinated individuals in the adult medicine clinics of a public hospital with a large outpatient HIV clinic during May 2021, and then excluded individuals with prior SARS-CoV-2 infection. We next 1:1 matched 100 PLWH to 100 outpatient HIV-negative adult medicine patients receiving care for chronic medical conditions on days since completion of second vaccination (minimum 10), sex, age +/-5 years, and the type of mRNA vaccine received. We defined a non-response as reciprocal pseudovirus neutralizing titer< 10 and anti-RBD IgG< 10 relative fluorescent units, and compared non-response by HIV status using mixed models.

Results

In each matched group there were 13 women; 25 received the mRNA-1273 vaccine and 75 received the BNT162b2 vaccine; the median age was 59. The median time from second vaccination was 35 days (IQR: 20–63). Among PLWH, the median CD4+ T-cell count was 511 (IQR: 351–796) and 5 individuals had HIV RNA > 200.

We found 2.4-fold greater odds of pseudovirus neutralizing antibody non-response among PLWH compared to people without HIV (95% CI=1.1–5.4). Although few individuals in each group did not mount an IgG response (12 among PLWH vs. 5; p=0.08), continuous anti-RBD IgG concentrations were 43% lower among PLWH (95% CI=0.36–0.88).

Among PLWH, when adjusting for age, sex, and days post-vaccination, each 100-cell increase in CD4+T-cell count was associated with 22% higher neutralizing antibody titers (GMR 1.22; 95% CI=1.09–1.37). Unsuppressed HIV RNA >200 was associated with 89% lower neutralizing antibody titers (GMR 0.11; 95% CI=0.01–0.84). Receipt of the BNT162b2 vs. mRNA-1273 vaccine was associated with 77% lower neutralizing titers (GMR 0.23; 95% CI=0.08–0.65) among PLWH.

Post-mRNA Vaccination SARS-CoV-2 IgG Concentrations and Pseudovirus Neutralizing Titers by HIV Status and Vaccine

Conclusion

PLWH had lower than expected response to mRNA SARS-CoV-2 vaccines, with the highest non-response among those with low CD4+ counts, unsuppressed HIV RNA, and those who received the BNT162b2 vaccine. Immunization strategies to improve immune responses among PLWH should be studied, and may include booster vaccination or preference of the mRNA-1273 vaccine in this group.

Disclosures

Matthew A. Spinelli, MD, MAS, Nothing to disclose Monica Gandhi, MD, MPH, Nothing to disclose

Frequency of post treatment control varies by antiretroviral therapy restart and viral load criteria

Clinical trials including an analytical treatment interruption (ATI) are vital for evaluating the efficacy of novel strategies for HIV remissions. We briefly describe an interactive tool for predicting viral rebound timing in ATI trials and the impact of posttreatment controller (PTC) definitions on PTC frequency estimates. A 4-week viral load threshold of 1000 cps/ml provides both high specificity and sensitivity for PTC detection. PTC frequency varies greatly based on the definition of a PTC.

A cell-free antigen processing system reveals antigenic factors critical for HIV-1 epitope dominance and informs vaccine design

Certain CD4+T cell epitopes have been associated with immune control of HIV-1 replication and the presence of anti-Env neutralizing antibodies. However, it remains unclear what antigen-dependent factors influence the dominance of certain epitopes in HIV-1 proteins. To study HIV-1 epitope dominance, we used a cell-free antigen processing system previously developed by our group that utilizes soluble HLA-DR1*01:01 (DR1), HLA-DM (DM), protein antigen and three cathepsins in a reducing and low pH environment to allow for antigen binding and cleavage. We subjected HIV-1 antigens from Gag, Pol, Env and accessory proteins Vif, Nef, Tat, and Rev to this system. Immunoprecipitation of pMHC-II complexes followed by peptide elution and identification via LC-MS/MS revealed a map of DR1-bound epitopes across the near-full length HIV-1 proteome. Most identified epitopes were DM-resistant, and in some cases, DM narrowed the epitope diversity to one species. Importantly, we identified 28 novel epitopes, including several glycopeptides eluted from DR1. We noted epitope “hot spots” in HIV-1 antigens and striking similarities in epitopes from HIV polyproteins (Gag precursor) versus individual subunits (Gag capsid). Analysis of the location of several epitopes from smaller HIV-1 proteins based on their known crystal structures mapped to regions of low protein stability and higher solvent accessibility. Finally, we found that several epitopes induced memory CD4+T cell responses in persons living with HIV-1. Thus, by using a minimalist in vitro processing system, we can interrogate novel HIV-1 epitopes and understand how DM-resistance and antigen structure influence epitope dominance, which has important implications for vaccine design.

HIV cure research in the time of COVID-19 - Antiretroviral therapy treatment interruption trials: A discussion paper

This discussion paper addresses the safety of HIV cure studies, particularly those involving stopping antiretroviral therapy, known as an analytic treatment interruption (ATI) in the context of the SARS-CoV-2 pandemic. More than 30 studies listed on ClinicalTrials.gov include an ATI and many others were planned to begin over the next 12 months but most were halted due to the COVID-19 pandemic. We consider the ethics, risks and practical considerations to be taken into account before re-opening HIV cure clinical trials, noting the specific risks of ATI in the context of circulating SARS-CoV-2.

HIV elite control is associated with reduced TRAILshort expression

OBJECTIVE

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) dependent apoptosis has been implicated in CD4 T-cell death and immunologic control of HIV-1 infection. We have described a splice variant called TRAILshort, which is a dominant negative ligand that antagonizes TRAIL-induced cell death in the context of HIV-1 infection. HIV-1 elite controllers naturally control viral replication for largely unknown reasons. Since enhanced death of infected cells might be responsible, as might occur in situations of low (or inhibited) TRAILshort, we tested whether there was an association between elite controller status and reduced levels of TRAILshort expression.

DESIGN

Cohort study comparing TRAILshort and full length TRAIL expression between HIV-1 elite controllers and viremic progressors from two independent populations.

METHODS

TRAILshort and TRAIL gene expression in peripheral blood mononuclear cells (PBMCs) was determined by RNA-seq. TRAILshort and TRAIL protein expression in plasma was determined by antibody bead array and proximity extension assay respectively.

RESULTS

HIV-1 elite controllers expressed less TRAILshort transcripts in PBMCs (P = 0.002) and less TRAILshort protein in plasma (P < 0.001) than viremic progressors.

CONCLUSION

Reduced TRAILshort expression in PBMCs and plasma is associated with HIV-1 elite controller status.

Blunted response to combination antiretroviral therapy in HIV elite controllers: an international HIV controller collaboration

Objective

HIV “elite controllers” (ECs) spontaneously control viral load, but some eventually require combination antiretroviral treatment (cART), due to a loss of viral control or a decline in CD4 T-cell counts. Here we studied the CD4 T-cell count dynamics after cART initiation among 34 ECs followed in U.S. and European cohorts, by comparison with chronically viremic patients (VIRs).

Methods

ECs were defined as patients with at least ≥5 viral load (VL) measurements below 400 copies/mL during at least a 5-year period despite never receiving ART and were selected from the French ANRS CO18 cohort, the U.S. SCOPE cohort, the International HIV Controllers study and the European CASCADE collaboration. VIRs were selected from the ANRS COPANA cohort of recently-diagnosed (<1 year) ART-naïve HIV-1-infected adults. CD4 T-cell count dynamics after cART initiation in both groups were modelled with piecewise mixed linear models.

Results

After cART initiation, CD4 T-cell counts showed a biphasic rise in VIRs with: an initial rapid increase during the first 3 months (+0.63/month), followed by +0.19/month. This first rapid phase was not observed in ECs, in whom the CD4Tc count increased steadily, at a rate similar to that of the second phase observed in VIRs. After cART initiation at a CD4 T-cell count of 300/mm³, the estimated mean CD4 T-cell gain during the first 12 months was 139/mm³ in VIRs and 80/mm³ in ECs (p = 0.048).

Conclusions

cART increases CD4 T-cell counts in elite controllers, albeit less markedly than in other patients.

Temporal changes in HCV genotype distribution in three different high risk populations in San Francisco, California

Background

Hepatitis C virus (HCV) genotype (GT) has become an important measure in the diagnosis and monitoring of HCV infection treatment. In the United States (U.S.) HCV GT 1 is reported as the most common infecting GT among chronically infected patients. In Europe, however, recent studies have suggested that the epidemiology of HCV GTs is changing.

Methods

We assessed HCV GT distribution in 460 patients from three HCV-infected high risk populations in San Francisco, and examined patterns by birth cohort to assess temporal trends. Multiple logistic regression was used to assess factors independently associated with GT 1 infection compared to other GTs (2, 3, and 4).

Results

Overall, GT 1 was predominant (72.4%), however younger injection drug users (IDU) had a lower proportion of GT 1 infections (54.7%) compared to older IDU and HIV-infected patients (80.5% and 76.6%, respectively). Analysis by birth cohort showed increasing proportions of non-GT 1 infections associated with year of birth: birth before 1970 was independently associated with higher adjusted odds of GT 1: AOR 2.03 (95% CI: 1.23, 3.34). African-Americans as compared to whites also had higher adjusted odds of GT 1 infection (AOR: 3.37; 95% CI: 1.89, 5.99).

Conclusions

Although, HCV GT 1 remains the most prevalent GT, especially among older groups, changes in GT distribution could have significant implications for how HCV might be controlled on a population level and treated on an individual level.

Bacterial meningitis among cochlear implant recipients--Canada, 2002

INTRODUCTION

In July 2002, a cluster of bacterial meningitis (BM) cases was identified among European cochlear implant recipients (CIRs), prompting Health Canada to conduct a retrospective cohort study to determine the rate of BM infection among Canadian CIRs and to identify risk factors for acquiring BM.

METHODS

A survey was mailed to 1,432 Canadian CIRs who had received implants during January 1995-July 2002 to assess occurrence of postimplant BM infection. Data collection included demographics, episodes of meningitis, and vaccination status.

RESULTS

A total of 1,024 (72%) surveys were completed. Median age of CIRs at implantation was 16 years (range: 7 months-81 years). Five (0.5%) cases of BM infection were reported (two pneumococcal, one meningococcal, and two of unknown etiology); one CIR died. Four cases occurred among children aged <18 years. Time between implantation and BM infection varied (range: 7 months-7.7 years; median: 11 months). The rate of BM infection per 1,000 person-years was 0.7 among CIRs aged > or =18 years and 2.9 among those aged <18 years. The proportion of CIRs vaccinated against pneumococcal and meningococcal disease was low (46% and 41%, respectively). Preimplant meningitis was identified as a risk factor for postimplant BM (p = 0.002). No other risk factors evaluated were associated with an increased risk for BM infection.

CONCLUSION

CIRs have a high rate of postimplant BM infection. Preimplant BM infection was identified as a risk factor. Cases of BM infection might have been prevented through vaccination.

Modified anthrax fusion proteins deliver HIV antigens through MHC Class I and II pathways

T cell-based HIV vaccine candidates have focused on eliciting both CD4- and CD8-mediated responses. One challenge in vaccine development is the successful introduction and presentation of exogenous antigen to elicit an immune response. Modified bacterial toxins have been studied extensively as intracellular delivery agents because of their unique capability to translocate antigen across the cell membrane without affecting cell viability. Modified anthrax toxin lethal factor (LFn) fusion protein is able to effectively induce anti-HIV cytotoxic T lymphocytes in the absence of protective antigen (PA) and is being evaluated as a vaccine candidate. Here we describe, for the first time, the processing and presentation of LFn fusion proteins by the MHC Class II pathway. The ability of LFn--HIV to induce both CD8- and CD4-mediated responses may have relevance in current approaches to vaccine design. Furthermore, the translocation and presentation of antigens occurs in the absence of PA, which proposes a modified molecular mechanism of antigen presentation by the anthrax toxin model. Additionally, we found that LFn--HIV is specific and sensitive in detecting HIV-specific CD4(+) and CD8(+) T cell responses in T cell assays, further broadening the value of this antigen delivery system as a useful immunologic tool.

Poor CD4 T cell restoration after suppression of HIV-1 replication may reflect lower thymic function

OBJECTIVE

To characterize immune phenotype and thymic function in HIV-1-infected adults with excellent virologic and poor immunologic responses to highly active antiretroviral therapy (HAART).

METHODS

Cross-sectional study of patients with CD4 T cell rises of > or = 200 x 10(6) cells/l (CD4 responders; n = 10) or < 100 x 10(6) cells/l (poor responders; n = 12) in the first year of therapy.

RESULTS

Poor responders were older than CD4 responders (46 versus 38 years; P < 0.01) and, before HAART, had higher CD4 cell counts (170 versus 35 x 106 cells/l; P = 0.11) and CD8 cell counts (780 versus 536 x 10(6) cells/l; P = 0.02). After a median of 160 weeks of therapy, CD4 responders had more circulating naive phenotype (CD45+CD62L+) CD4 cells (227 versus 44 x 10(6) cells/l; P = 0.001) and naive phenotype CD8 cells (487 versus 174 x 10(6) cells/l; P = 0.004) than did poor responders (after 130 weeks). Computed tomographic scans showed minimal thymic tissue in 11/12 poor responders and abundant tissue in 7/10 responders (P = 0.006). Poor responders had fewer CD4 cells containing T cell receptor excision circles (TREC) compared with CD4 responders (2.12 versus 27.5 x 10(6) cells/l; P = 0.004) and had shorter telomeres in CD4 cells (3.8 versus 5.3 kb; P = 0.05). Metabolic labeling studies with deuterated glucose indicated that the lower frequency of TREC-containing lymphocytes in poor responders was not caused by accelerated proliferation kinetics.

CONCLUSION

Poor CD4 T cell increases observed in some patients with good virologic response to HAART may be caused by failure of thymic T cell production.

Implications of antiretroviral resistance on viral fitness

Treatment of HIV infected patients with antiretroviral drugs often results in the emergence of virus variants with reduced sensitivity to these drugs. However, the viral load often remains partially suppressed below pretherapy levels, which might be explained by a reduced fitness of the drug resistant viral population. This review describes the effects of antiretroviral resistance development on the fitness of the viral population and its clinical implications.

Factors influencing T-cell turnover in HIV-1-seropositive patients

HIV-1 disease is associated with pathological effects on T-cell production, destruction, and distribution. Using the deuterated (2H) glucose method for endogenous labeling, we have analyzed host factors that influence T-cell turnover in HIV-1-uninfected and -infected humans. In untreated HIV-1 disease, the average half life of circulating T cells was diminished without compensatory increases in cell production. Within 12 weeks of the initiation of highly active antiretroviral therapy (HAART), the absolute production rates of circulating T cells increased, and normal half-lives and production rates were restored by 12-36 months. Interpatient heterogeneity in the absolute degree of turnover correlated with the relative proportion of naive- and memory/effector-phenotype T cells in each of the CD4+ and CD8+ populations. The half-lives of naive-phenotype T cells ranged from 116-365 days (fractional replacement rates of 0.19-0.60% per day), whereas memory/effector-phenotype T cells persisted with half-lives from 22-79 days (fractional replacement rates of 0.87-3.14% per day). Naive-phenotype T cells were more abundant, and the half-life of total T cells was prolonged in individuals with abundant thymic tissue, as assessed by computed tomography. Such interpatient variation in T-cell kinetics may be reflective of differences in functional immune reconstitution after treatment for HIV-1 disease.

Efficacy and safety of adefovir dipivoxil with antiretroviral therapy: a randomized controlled trial

CONTEXT

Adefovir dipivoxil is a nucleotide analog that has demonstrated effective antiretroviral activity against human immunodeficiency virus (HIV) with once-daily administration.

OBJECTIVE

To determine if adefovir confers antiretroviral or immunologic benefit when added to stable antiretroviral therapy.

DESIGN

Multicenter, 24-week, randomized, double-blind, placebo-controlled study. Enrollment was conducted from June 3, 1996, through May 6, 1997.

SETTING

Thirty-three US HIV treatment centers.

PARTICIPANTS

Of 1171 patients screened, 442 patients infected with HIV receiving stable antiretroviral therapy for at least 8 weeks with plasma HIV RNA greater than 2500 copies/mL and CD4+ cell count above 0.20 x 10(9)/L were randomized.

INTERVENTION

Patients were randomized to receive either a single 120-mg/d dose of adefovir dipivoxil (n = 219) or an indistinguishable placebo (n = 223). All patients received L-carnitine, 500 mg/d. Open-label adefovir was offered after 24 weeks and was continued until the end of the study.

MAIN OUTCOME MEASURES

Changes in HIV RNA from baseline, based on area under the curve and CD4+ cell levels, adverse events, and effect of baseline genotypic resistance on response to adefovir.

RESULTS

Patients assigned to adefovir demonstrated a 0.4-log10 decline from baseline in HIV RNA compared with no change in the placebo group (P<.001), which continued through 48 weeks. CD4+ cell counts did not change. During the initial 24 weeks, elevated hepatic enzyme levels (P<.001), gastrointestinal tract complaints (P<.001), and weight loss (P<.001) were associated with use of adefovir. Between 24 weeks and 48 weeks elevations in serum creatinine occurred in 60% of patients, usually returning to baseline after discontinuation of adefovir. Patients with lamivudine or lamivudine and zidovudine resistance mutations demonstrated anti-HIV effects with adefovir (P< or =.01 vs placebo group).

CONCLUSIONS

This study suggests that once-daily adefovir therapy reduces HIV RNA and is active against isolates resistant to lamivudine or lamivudine and zidovudine. Nephrotoxicity occurred when treatment extended beyond 24 weeks but was reversible.

Pneumococcal immunization and public health: the Canadian experience

Pneumococcal vaccine has been poorly used in Canada, despite strong recommendations for its use by the Canadian National Advisory Committee on Immunization. In a recent survey of health officials, however, seven of the 12 Canadian provinces and territories were found to either have a programme for all persons > 65 years of age or were planning to implement one within the next year. Factors that have contributed to this increased interest include: better data on disease incidence and preventable illness from population-based surveillance; data on emerging resistance of Streptococcus pneumoniae in Canada to penicillin and other antimicrobials; implementation of vaccine programmes for the elderly by public health officials in Ontario, Nova Scotia and British Columbia; completion of a cost-benefit study of pneumococcal vaccine for Canada; and increased attention to pneumococcal vaccination at national immunization meetings and in the medical literature. Increased availability of vaccine and competitive pricing are also making programmes for the elderly more feasible and affordable. A national meeting entitled 'Preventing Pneumococcal Disease: A Canadian Consensus Conference' was held in February 1998 to further build on this growing interest.

Time course of cerebrospinal fluid responses to antiretroviral therapy: evidence for variable compartmentalization of infection

OBJECTIVES

To compare the kinetics and magnitude of HIV-1 RNA responses to antiretroviral therapy (ART) in the cerebrospinal fluid (CSF) and plasma.

DESIGN

Repeated lumbar punctures (LPs) were performed after the initiation or change in ART in 15 HIV-1-infected subjects, with the focus on two phases of response: an acute phase within the first 11 days, for which crude estimates of viral RNA half-lives and decay rates were derived and CSF:plasma relative decay ratios quantitatively analysed; and a longer-term phase beyond 4 weeks that was descriptively assessed.

RESULTS

In 13 subjects studied during the acute phase, the crude HIV-1 RNA half-life was longer (median 2.0 compared with 1.9 days), the decay rate slower (median 0.13 compared with 0.16 log10 copies/day) and, most notably, the variability greater (intraquartile range of half-life 1.8-4.3 compared with 1.7-2.1 days) in the CSF than in the plasma. A slower decay in the CSF correlated with lower initial blood CD4 T lymphocyte counts (P = 0.001). Seven of 11 subjects studied at 4 weeks or later, including some with slower acute-phase CSF responses, showed greater or more durable viral suppression in the CSF.

CONCLUSION

Divergent acute-phase viral kinetics in the CSF and plasma, and proportionally greater long-term decrements in CSF HIV-1 RNA in slow early-responders or poor overall plasma responders indicate variable compartmentalization of CSF infection, consistent with a model of two prototypes of CSF infection: short-lived, transitory infection that predominates in early HIV-1 infection and longer-lived, more autonomous CSF infection predominating in late HIV-1 infection. Additional studies will be needed to define more precisely the acute and longer-term CSF kinetics in different clinical settings and to assess this model.

Failure of physicians to consider the diagnosis of pertussis in children

To determine the ability of physicians to make a diagnosis of pertussis and factors associated with improved diagnosis, 8,235 children from 88 child care centers and 14 elementary schools from Quebec City, Quebec, Canada, were evaluated by using a questionnaire completed by parents and a medical record review. Children must have consulted a physician to be included in the evaluation. There were 558 children meeting the surveillance case definition and 416 meeting a modified World Health Organization case definition who consulted a physician. A diagnosis of pertussis was considered in 24%-26% of children meeting either case definition, made in 12%-14%, and reported for 6%. Pertussis diagnosis was significantly associated with having a history of pertussis exposure (P < or = .003), four pertussis-related symptoms (P < .001), and a cough for > or = 5 weeks (P < or = .05) and consulting in a hospital setting (P < or = .03). The proportion of cases of pertussis diagnosed and reported is low even when children present with classical symptoms.

Directly measured kinetics of circulating T lymphocytes in normal and HIV-1-infected humans

The dynamic basis for T-cell depletion in late-stage HIV-1 disease remains controversial. Using a new, non-radioactive, endogenous labeling technique, we report direct measurements of circulating T-cell kinetics in normal and in HIV-1-infected humans. In healthy, HIV-1-seronegative subjects, CD4+ and CD8+ T cells had half-lives of 87 days and 77 days, respectively, with absolute production rates of 10 CD4+ T cells/microl per day and 6 CD8+ T cells/microl per day. In untreated HIV-1-infected subjects (with a mean CD4 level of 342 cells/microl), the half-life of each subpopulation was less than 1/3 as long as those of healthy, HIV-1-seronegative subjects but was not compensated by an increased absolute production rate of CD4+ T cells. After viral replication was suppressed by highly active antiretroviral therapy for 12 weeks, the production rates of circulating CD4+ and CD8+ T cells were considerably elevated; the kinetic basis of increased CD4 levels was greater production, not a longer half-life, of circulating cells. These direct measurements indicate that CD4+ T-cell lymphopenia is due to both a shortened survival time and a failure to increase the production of circulating CD4+ T cells. Our results focus attention on T-cell production systems in the pathogenesis of HIV-1 disease and the response to antiretroviral therapy.

Curdlan sulfate (CRDS) in a 21-day intravenous tolerance study in human immunodeficiency virus (HIV) and cytomegalovirus (CMV) infected patients: indication of anti-CMV activity with low toxicity

This study evaluated tolerance (and possible efficacy) for 21 days of i.v. administration at three dose levels of curdlan sulfate (CRDS) (a semisynthetic sulfated polysaccharide), administered over 30 minutes, in HIV and CMV (in some cases) infected individuals with CD4 levels < 500 cells/mm3. Half of the subjects were previously treated with reverse transcriptase inhibitors (RTI) (which were continued during the CRDS administration) and half the patients had no prior RTI treatment. Evaluation of other sulfated polysaccharides in HIV had been discontinued due to side effects and lack of activity. Three groups of HIV patients (also including subsets with CMV infection) were treated separately with 50 mg/70 Kg, 100 mg/70 Kg and 200 mg/70 Kg of CRDS infused i.v. over thirty minutes daily for 21 days. In each dose group, half of the patients selected were being treated with a RTI and half were on no RTI. Patients were monitored for CD4 cell levels, viral load in some cases, and safety parameters in blood. Samples of urine and semen were additionally taken for CMV by culture and for PCR assay in subsets of participants. CRDS in this 21 day study was well-tolerated and produced few reportable side effects. Systematic decreases in platelets and increases in p24 antigen previously seen with dextran sulfate were not observed in this study with CRDS. In the 21 patients testing positive for CMV at the start of the study, 12 were CMV negative at the end of 21 days. In an untreated historical control group, 0/36 went from CMV positive to negative over a period of 13-15 years. The anti-CMV activity of CRDS in this study, therefore, had a p value < 0.001, based on these historical controls. The marked temporary increases in CD4 levels seen in the single dose and the seven-day CRDS studies on HIV patients were also seen for 21 days in the current study (p = 0.0001). Treatment with CRDS seems promising against CMV in HIV infected patients, even with once daily dosing of this two-hour half-life drug. CRDS was well tolerated and its lack of toxicity makes it an attractive candidate for CMV-infected HIV patients. Multiple daily dosing, or the continuous infusion of CRDS, could lead to increased effectiveness against both HIV and CMV, especially in combination with other agents. Given the toxicity of existing anti-CMV agents, and considering the emerging importance of CMV in atherosclerotic disease, further studies on CRDS are warranted.

An approach to antiretroviral treatment of HIV disease. Combined antiretroviral therapy: the emerging role

Early, aggressive antiretroviral therapy may soon be considered state of the art. A new generation of antiretroviral agents will soon be available, many of them well tolerated and effective, particularly when used in combination with zidovudine and other nucleoside analogues. Combined antiretroviral therapy represents a significant step forward in the management of HIV infection.

Maintenance of normal rat mammary epithelial cells by insulin and insulin-like growth factor 1

Normal rat mammary epithelial cells were cultured within a rat tail collagen gel matrix formed under improved conditions for controlling pH and osmolarity. Under these conditions, growth can be maintained for up to 3 weeks with a 10- to 15-fold increase in cell number. The cells grow in response to prolactin, progesterone, epidermal growth factor, and cholera toxin, in a medium of DME: Ham's F12 supplemented with BSA and insulin at 10 micrograms/ml. When the insulin concentration was reduced to more physiological levels (10 ng/ml) the cells did not grow. However, at these more physiological concentrations it could be shown that insulin had a concentration-dependent effect on the maintenance of the cells with an optimum concentration around 25 ng/ml. The cells could be maintained in hormone-supplemented medium with low levels of insulin in a quiescent state for up to 14 days. The high levels of insulin needed for optimal growth could be replaced by insulin-like growth factor 1 (IGF-1) at much lower concentrations (25-50 ng/ml). The superphysiological level of insulin required for optimum growth is probably due to its acting weakly through an IGF-1-mediated growth-promoting mechanism. Insulin's effect on cell maintenance occurs at physiological levels and may better reflect its role in mammary cell growth.