Dynamics of HIV-1 replication following influenza vaccination of HIV+ individuals

Impact of influenza and pneumococcal vaccines on HIV persistence and immune dynamics during suppressive antiretroviral therapy

OBJECTIVE

We sought to determine if standard influenza and pneumococcal vaccines can be used to stimulate HIV reservoirs during antiretroviral therapy (ART).

DESIGN

A prospective, randomized, double-blinded, placebo-controlled, crossover trial of two clinically recommended vaccines (influenza and pneumococcal).

METHODS

Persons with HIV on ART ( N  = 54) were enrolled in the clinical trial. Blood was collected at baseline and days 2,4,7,14, and 30 postimmunizations. Levels of cellular HIV RNA and HIV DNA were measured by ddPCR. Expression of immunological markers on T cell subsets was measured by flow cytometry. Changes in unspliced cellular HIV RNA from baseline to day 7 postinjection between each vaccine and placebo was the primary outcome.

RESULTS

Forty-seven participants completed at least one cycle and there were no serious adverse events related to the intervention. We observed no significant differences in the change in cellular HIV RNA after either vaccine compared with placebo at any timepoint. In secondary analyses, we observed a transient increase in total HIV DNA levels after influenza vaccine, as well as increased T cell activation and exhaustion on CD4 + T cells after pneumococcal vaccine.

CONCLUSION

Clinically recommended vaccines were well tolerated but did not appear to stimulate the immune system strongly enough to elicit significantly noticeable HIV RNA transcription during ART.Clinicaltrials.gov identifier: NCT02707692.

SARS-CoV-2 mRNA Vaccines Induce Greater Complement Activation and Decreased Viremia and Nef Antibodies in Men With HIV-1

BACKGROUND

Immune dysregulation in people with human immunodeficiency virus-1 (PWH) persists despite potent antiretroviral therapy and, consequently, PWH tend to have lower immune responses to licensed vaccines. However, limited information is available about the impact of mRNA vaccines in PWH. This study details the immunologic responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccines in PWH and their impact on HIV-1.

METHODS

We quantified anti-S immunoglobulin G (IgG) binding and neutralization of 3 SARS-CoV-2 variants of concern and complement activation in blood from virally suppressed men with HIV-1 (MWH) and men without HIV-1 (MWOH), and the characteristics that may impact the vaccine immune responses. We also studied antibody levels against HIV-1 proteins and HIV-1 plasma RNA.

RESULTS

MWH had lower anti-S IgG binding and neutralizing antibodies against the 3 variants compared to MWOH. MWH also produced anti-S1 antibodies with a 10-fold greater ability to activate complement and exhibited higher C3a blood levels than MWOH. MWH had decreased residual HIV-1 plasma viremia and anti-Nef IgG approximately 100 days after immunization.

CONCLUSIONS

MWH respond to SARS-CoV-2 mRNA vaccines with lower antibody titers and with greater activation of complement, while exhibiting a decrease in HIV-1 viremia and anti-Nef antibodies. These results suggest an important role of complement activation mediating protection in MWH.

A link between IL-23 and anti-CD4 autoantibody production in antiretroviral-treated HIV-infected individuals

Potential mechanisms of poor CD4+ T cell reconstitution after viral suppression with antiretroviral therapy (ART) in HIV disease have been extensively investigated. We recently discovered that anti-CD4 autoantibody plays a role in impaired CD4+ T cell recovery from ART in HIV-infected individuals with viral suppression, which accounts for a mechanism specific for CD4+ T cell depletion. However, the mechanism of pathologic anti-CD4 autoantibody production in treated HIV disease remains unknown. Here we report that seasonal influenza vaccination induced IgG anti-CD4 autoantibodies, predominant IgG3 subclass, in some viral-suppressed ART-treated HIV+ subjects. To explore the mechanism of anti-CD4 antibody production in this population, we performed and analyzed gene profiles in isolated B cells using a gene microarray and plasma 32 cytokines. Notably, both gene expression and multiple cytokine analyses showed pre-vaccination plasma level of IL-23 was the key cytokine linked to IgG anti-CD4 antibody production in response to immunization in vivo Exogenous rIL-23 increased autoreactive IgG binding on CD4+ T cells from HIV+ subjects in vitro Results from this study may reveal a role of IL-23 in anti-CD4 autoantibody production in treated HIV.IMPORTANCEIn our published studies, we determine that pathological anti-CD4 IgGs from immunologic non-responders on virally-suppressive ART (CD4 cell counts < 350 cells/μL) mediated CD4+ T cell death via antibody-mediated cytotoxicity (ADCC), which play a role in poor CD4+ T cell recovery from ART. Up to 25% of HIV-infected individuals are non-responders and demonstrate increased morbidity and mortality. However, the mechanism of anti-CD4 autoantibody production in treated HIV remains unknown. In this study, we report that IL-23 may be the key cytokine to promote anti-CD4 autoantibody production after immunization in ART-treated HIV-infected individuals.

Safety and Immunogenicity of Conventional Subunit and MF59-adjuvanted Influenza Vaccines in Human Immunodeficiency Virus-1-seropositive Patients

In this study of influenza vaccination, 37 human immunodeficiency virus (HIV)-1-seropositive patients were randomized to receive either a vaccine with a conventional subunit or one adjuvanted with MF59. Blood samples were collected at the time of vaccination, and then 30 and 180 days later, to evaluate immunogenicity, CD4+ T-lymphocyte count and HIV-1 RNA levels. Seroconversion rates against the three viral strains included in the vaccine ranged between 44% and 72% and 53% and 68% for the adjuvanted vaccine and the subunit vaccine, respectively. Other criteria of the European Medicines Evaluation Agency were also met. Vaccination was not associated with serious adverse events. Local and systemic effects were mild and of short duration. CD4+ T-lymphocyte counts and viraemia levels were not negatively affected by vaccination. These results confirmed the safety and immunogenicity of these currently available vaccines in HIV-1-seropositive patients, thus supporting the recommendation for influenza immunization in this high-risk category.

Impairment of the humoral and CD4(+) T cell responses in HTLV-1-infected individuals immunized with tetanus toxoid

T cells from HTLV-1-infected individuals have a decreased ability to proliferate after stimulation with recall antigens. This abnormality may be due to the production of regulatory cytokine or a dysfunctional antigen presentation. The aims of this study were to evaluate the antibody production and cytokine expression by lymphocytes before and after immunization with tetanus toxoid (TT) and to evaluate the immune response of monocytes after stimulation with TT and frequency of dendritic cells (DC) subsets. HTLV-1 carriers (HC) and uninfected controls (UC) with negative serology for TT were immunized with TT, and the antibody titers were determined by ELISA as well as the cell activation markers expression by monocytes. The frequencies of DC subsets were determined by flow cytometry. Following immunization, the IgG anti-TT titers and the frequency of CD4(+) T cells expressing IFN-γ, TNF-α and IL-10 in response to TT were lower in the HC than in the UC. Additionally, monocytes from HC did not exhibit increased HLA-DR expression after stimulation with TT, and presented low numbers of DC subsets, therefore, it's necessary to perform functional studies with antigen-presenting cells. Collectively, our finding suggests that HC present an impairment of the humoral and CD4(+) T cell immune responses after vaccination.

2013 IDSA clinical practice guideline for vaccination of the immunocompromised host

An international panel of experts prepared an evidenced-based guideline for vaccination of immunocompromised adults and children. These guidelines are intended for use by primary care and subspecialty providers who care for immunocompromised patients. Evidence was often limited. Areas that warrant future investigation are highlighted.

Short communication: HIV type 1 accumulates in influenza-specific T cells in subjects receiving seasonal vaccination in the context of effective antiretroviral therapy

Whether or not HIV-1 continues to infect cells in individuals treated with effective antiretroviral therapy (ART) remains controversial. Here, we determined whether the redistribution of the HIV-1 proviral burden with respect to antigen specificity of CD4(+) cells would provide evidence for ongoing infection cycles in vivo. HIV-1 preferentially infects antigen-stimulated CD4(+) T cells. In the setting of prolonged effective ART, we postulated that if infection cycles were occurring, influenza-specific CD4(+) T cells, activated by influenza vaccination, would preferentially accumulate proviral burden. Peripheral blood mononuclear cells (PBMCs) were collected from HIV-1-infected subjects who had been treated with effective ART for >5 years, before and after influenza vaccination. CD4(+) T cells were sorted by antigen specificity and HIV-1 proviral burdens were determined. Levels of HIV-1 production upon in vitro antigenic stimulation were also measured. At baseline, influenza-specific CD4(+) T cells carried higher HIV-1 proviral loads than HIV-1-p55-specific CD4(+) T cells. Upon influenza vaccination we observed trends toward elevated levels of HIV-1 proviral DNA in influenza and HIV-1-p55-specific, but not tetanus toxoid or cytomegalovirus (CMV)-specific CD4(+) T cells. Higher levels of HIV-1 virions were produced upon influenza stimulation in postvaccination as compared to baseline samples. While the trends toward increased proviral burdens in influenza-specific cells failed to reach statistical significance, our observation of disproportionately high levels of provirus in influenza-specific cells at baseline indicates that this may represent a real increase that is cumulative over multiple annual vaccinations. This has implications for the eradication of HIV-1 by adding to the evidence that the resting CD4(+) T cell viral reservoir is continually replenished in ART-treated subjects.

Influenza vaccination for immunocompromised patients: systematic review and meta-analysis by etiology

Many national guidelines recommend annual influenza vaccination of immunocompromised patients, although the decision to vaccinate is usually at clinical discretion. We conducted a systematic review and meta-analyses to assess the evidence for influenza vaccination in this group, and we report our results by etiology. Meta-analyses showed significantly lower odds of influenza-like illness after vaccination in patients with human immunodeficiency virus (HIV) infection, patients with cancer, and transplant recipients and of laboratory-confirmed influenza in HIV-positive patients, compared with patients receiving placebo or no vaccination. Pooled odds of seroconversion and seroprotection were typically lower in HIV-positive patients, patients with cancer, and transplant recipients, compared with immunocompetent controls. Vaccination was generally well tolerated, with variation in mild adverse events between etiological groups. Limited evidence of a transient increase in viremia and a decrease in the percentage of CD4(+) cells in HIV-positive patients was found although not accompanied by worsening of clinical symptoms. Clinical judgment remains important when discussing the benefits and safety profile with immunocompromised patients.

Variable effect of co-infection on the HIV infectivity: within-host dynamics and epidemiological significance

Background

Recent studies have implicated viral characteristics in accounting for the variation in the HIV set-point viral load (spVL) observed among individuals. These studies have suggested that the spVL might be a heritable factor. The spVL, however, is not in an absolute equilibrium state; it is frequently perturbed by immune activations generated by co-infections, resulting in a significant amplification of the HIV viral load (VL). Here, we postulated that if the HIV replication capacity were an important determinant of the spVL, it would also determine the effect of co-infection on the VL. Then, we hypothesized that viral factors contribute to the variation of the effect of co-infection and introduce variation among individuals.

Methods

We developed a within-host deterministic differential equation model to describe the dynamics of HIV and malaria infections, and evaluated the effect of variations in the viral replicative capacity on the VL burden generated by co-infection. These variations were then evaluated at population level by implementing a between-host model in which the relationship between VL and the probability of HIV transmission per sexual contact was used as the within-host and between-host interface.

Results

Our within-host results indicated that the combination of parameters generating low spVL were unable to produce a substantial increase in the VL in response to co-infection. Conversely, larger spVL were associated with substantially larger increments in the VL. In accordance, the between-host model indicated that co-infection had a negligible impact in populations where the virus had low replicative capacity, reflected in low spVL. Similarly, the impact of co-infection increased as the spVL of the population increased.

Conclusion

Our results indicated that variations in the viral replicative capacity would influence the effect of co-infection on the VL. Therefore, viral factors could play an important role driving several virus-related processes such as the increment of the VL induced by co-infections. These results raise the possibility that biological differences could alter the effect of co-infection and underscore the importance of identifying these factors for the implementation of control interventions focused on co-infection.

Influenza vaccination for immunocompromised patients: systematic review and meta-analysis from a public health policy perspective

BACKGROUND

Immunocompromised patients are vulnerable to severe or complicated influenza infection. Vaccination is widely recommended for this group. This systematic review and meta-analysis assesses influenza vaccination for immunocompromised patients in terms of preventing influenza-like illness and laboratory confirmed influenza, serological response and adverse events.

METHODOLOGY/PRINCIPAL FINDINGS

Electronic databases and grey literature were searched and records were screened against eligibility criteria. Data extraction and risk of bias assessments were performed in duplicate. Results were synthesised narratively and meta-analyses were conducted where feasible. Heterogeneity was assessed using I(2) and publication bias was assessed using Begg's funnel plot and Egger's regression test. Many of the 209 eligible studies included an unclear or high risk of bias. Meta-analyses showed a significant effect of preventing influenza-like illness (odds ratio [OR]=0.23; 95% confidence interval [CI]=0.16-0.34; p<0.001) and laboratory confirmed influenza infection (OR=0.15; 95% CI=0.03-0.63; p=0.01) through vaccinating immunocompromised patie nts compared to placebo or unvaccinated controls. We found no difference in the odds of influenza-like illness compared to vaccinated immunocompetent controls. The pooled odds of seroconversion were lower in vaccinated patients compared to immunocompetent controls for seasonal influenza A(H1N1), A(H3N2) and B. A similar trend was identified for seroprotection. Meta-analyses of seroconversion showed higher odds in vaccinated patients compared to placebo or unvaccinated controls, although this reached significance for influenza B only. Publication bias was not detected and narrative synthesis supported our findings. No consistent evidence of safety concerns was identified.

CONCLUSIONS/SIGNIFICANCE

Infection prevention and control strategies should recommend vaccinating immunocompromised patients. Potential for bias and confounding and the presence of heterogeneity mean the evidence reviewed is generally weak, although the directions of effects are consistent. Areas for further research are identified.

Influenza in immunocompromised patients: considerations for therapy

Influenza infection results in substantial morbidity and mortality in immunocompromised patients, and the risks for influenza and its related complications depend on the degree of immunosuppression. In addition to influenza vaccination and infection control precautions, two classes of antiviral drugs are currently approved for treatment and prophylaxis in uncomplicated infected patients. However, there are no randomized controlled trials assessing the efficacy and safety of licensed antivirals for influenza management in immunocompromised patients. The purpose of this article is to highlight some considerations for therapy in immunocompromised patients, the usefulness of vaccination for the prevention of influenza and the clinical interest in surveillance of antiviral resistance.

Poor immunogenicity of the H1N1 2009 vaccine in well controlled HIV-infected individuals

OBJECTIVE

To evaluate the safety and immunogenicity of the H1N1 2009 vaccine in HIV-positive individuals.

DESIGN

A single-arm study.

SETTING

Clinic at the Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA.

PARTICIPANTS

HIV-infected adults with an indication for H1N1 vaccination.

INTERVENTION

Single intramuscular 15 microg dose of the monovalent, unadjuvanted, inactivated, split virus H1N1 vaccine.

MAIN OUTCOMES

Immunogenicity, safety and tolerability.

RESULTS

A total of 120 participants were enrolled, 71% men, 68% African-American, with median age of 46 years. All of them but one were on antiretroviral treatment, with a median current CD4 cell counts of 502 cells/microl, and a nadir CD4 cell counts of 132 cells/microl. The HIV RNA level was below 400 copies/ml in 92% of participants. All participants completed the 3 weeks of follow-up. Thirty of the 120 (25%) participants had antibody hemagglutination-inhibition assay titers equal or greater than 1: 40 at baseline. Among participants without evidence of previous exposure, only 61% develop protective titers by week 3 of the study. Nonresponders had lower current and nadir CD4 cell counts than responders. Only four of nine participants with detectable HIV viral load at baseline developed protective antibody titers. Age and race were not predictors of the response to the vaccine. The vaccine was well tolerated.

CONCLUSION

These results suggest that only 60% of well controlled HIV-infected individuals without preexisting immunity to H1N1 develop protective antibody titers after immunization. Alternative vaccines, dosing, adjuvants or schedule strategies are needed to achieve effective immunization of this vulnerable population.

Influenza in immunosuppressed populations: a review of infection frequency, morbidity, mortality, and vaccine responses

Patients that are immunosuppressed might be at risk of serious influenza-associated complications. As a result, multiple guidelines recommend influenza vaccination for patients infected with HIV, who have received solid-organ transplants, who have received haemopoietic stem-cell transplants, and patients on haemodialysis. However, immunosuppression might also limit vaccine responses. To better inform policy, we reviewed the published work relevant to incidence, outcomes, and prevention of influenza infection in these patients, and in patients being treated chemotherapy and with systemic corticosteroids. Available data suggest that most immunosuppressed populations are indeed at higher risk of influenza-associated complications, have a general trend toward impaired humoral vaccine responses (although these data are mixed), and can be safely vaccinated--although longitudinal data are largely lacking. Randomised clinical trial data were limited to one study of HIV-infected patients with high vaccine efficacy. Better trial data would inform vaccination recommendations on the basis of efficacy and cost in these at-risk populations.

[Effects of influenza vaccination on the percentage of CD4+ T lymphocytes in HIV 1/2 positive patients: a cohort study]

OBJECTIVE

To determine the incidence of immunologic change in the percentage of CD4+ T lymphocytes in HIV 1/2 positive patients in the first quarter after influenza vaccination (P-CIR) and to compare the demographic and clinical characteristics associated with this change.

METHODS

We studied 105 patients with HIV/AIDS in a retrospective hospital cohort between 2001-2006. P-CIR was considered as a decrease of >3% in the prevaccination CD4+ percentage. Crude and adjusted OR (sex, age, antiretroviral therapy, clinical stability, prevaccination viremia and prevaccination total CD4) were evaluated by logistic regression (95%CI).

RESULTS

The incidence of P-CIR was 33.3%. P-CIR was persistent in 31.4% for 7 months after vaccination regardless of high prevaccination viremia. No association was found between demographic and clinical variables and P-CIR [crude OR: 0.90 (0.17-4.8); adjusted OR: 1.09 (0.17-6.8)].

CONCLUSIONS

The results showed that the immunological change after vaccination was not inconsiderable. However, this change was mainly transient.

Safety and immunogenicity of two influenza virus subunit vaccines, with or without MF59 adjuvant, administered to human immunodeficiency virus type 1-seropositive and -seronegative adults

The objective of this study was to evaluate and compare both the safety and tolerability and the humoral and cell-mediated immune responses for two influenza virus subunit vaccines, one with MF59 adjuvant (Fluad) and one without an adjuvant (Agrippal), in healthy and in human immunodeficiency virus type 1 (HIV-1)-infected adult individuals. To achieve this aim, an open, randomized, comparative clinical trial was performed during the 2005-2006 season. A total of 256 subjects were enrolled to receive one dose of vaccine intramuscularly. Blood samples were taken at the time of vaccination and at 1 and 3 months postvaccination. A good humoral antibody response was detected for both vaccines, meeting all the criteria of the Committee for Medical Products for Human Use. After Beyer's correction for prevaccination status, Fluad exhibited better immunogenicity than Agrippal, as shown from the analysis of the geometric mean titers, with significant differences for some virus strains; however, no definitive conclusions on the clinical significance of such results can be drawn, because the method used to estimate antibody response is currently nonstandard for influenza virus vaccines. Significant induction of an antigen-specific CD4+ T-lymphocyte proliferative response was detected at all time points after immunization, for both the vaccines, among HIV-1-seronegative subjects. This was different from what was observed for HIV-1-infected individuals. In this group, significance was not reached at 30 days postvaccination (T30) for those immunized with Agrippal. Also when data were compared between treatment groups, a clear difference in the response at T30 was observed in favor of Fluad (P = 0.0002). The safety profiles of both vaccines were excellent. For HIV-1-infected individuals, no significant changes either in viremia or in the CD4+ cell count were observed at any time point. The results showed good safety and immunogenicity for both vaccines under study for both uninfected and HIV-1-infected adults, confirming current recommendations for immunization of this high-risk category.

Efficacy and clinical effectiveness of influenza vaccines in HIV-infected individuals: a meta-analysis

Background

Though influenza vaccines are the cornerstone of medical interventions aimed at protecting individuals against epidemic influenza, their effectiveness in HIV infected individuals is not certain. With the recent detection of influenza strains in countries with high HIV prevalence rates, we aimed at evaluating the current evidence on the efficacy and clinical effectiveness of influenza vaccines in HIV-infected individuals.

Methods

We used electronic databases to identify studies assessing efficacy or effectiveness of influenza vaccines in HIV patients. We included studies that compared the incidence of culture- or serologically-confirmed influenza or clinical influenza-like illness in vaccinated to unvaccinated HIV infected individuals. Characteristics of study participants were independently abstracted and the risk difference (RD), the number needed to vaccinate to prevent one case of influenza (NNV) and the vaccine effectiveness (VE) computed.

Results

We identified six studies that assessed the incidence of influenza in vaccinated HIV-infected subjects. Four of these studies compared the incidence in vaccinated versus unvaccinated subjects. These involved a total of 646 HIV-infected subjects. In all the 4 studies, the incidence of influenza was lower in the vaccinated compared to unvaccinated subjects with RD ranging from -0.48 (95% CI: -0.63, -0.34) to -0.15 (95% CI: -0.25, 0.05); between 3 and 7 people would need to be vaccinated to prevent one case of influenza. Vaccine effectiveness ranged from 27% to 78%. A random effects model was used to obtain a summary RD of -0.27 (95%CI: -0.42, -0.11). There was no evidence of publication bias.

Conclusion

Current evidence, though limited, suggests that influenza vaccines are moderately effective in reducing the incidence of influenza in HIV-infected individuals. With the threat of a global influenza pandemic, there is an urgent need to evaluate the effectiveness of influenza vaccines in trials with a larger number of representative HIV-infected persons.

Humoral response to hepatitis B vaccination and its relationship with T CD45RA+ (naïve) and CD45RO+ (memory) subsets in HIV-1-infected subjects

HIV disease leads to defects in cell-mediated immunity, impairing the immune response to new and recall antigens. We studied 55 HIV 1-infected patients who received of recombinant DNA hepatitis B vaccine and 20 controls. The overall hepatitis B virus (HBV) seroconversion rate was 59%. The median CD4+ T cell count among responders was 452 cell/mm(3), higher than non-responders (359 cells/mm(3)). The HIV plasmaviral loads were higher in non-responders. We concluded that total T CD4 cell count, memory T CD4+ cells and lower plasma viral load among HIV-1-infected subjects treated with HAART could be used to predict the immune response to vaccination with hepatitis B vaccine. Thus, considering cost benefits, HVB vaccination should be preferentially provided to HIV-infected patients with T CD4 cells count over 450 cells/mm(3), preferentially whose under HIV replication controlled.

Antibody responses and HIV-1 viral load in HIV-1-seropositive subjects immunised with either the MF59-adjuvanted influenza vaccine or a conventional non-adjuvanted subunit vaccine during highly active antiretroviral therapy

OBJECTIVE

To study immunological and virological parameters in HIV-1-seropositive adults treated with highly active antiretroviral therapy (HAART) for at least 7 months after immunisation with MF59-adjuvanted (FLUAD, Chiron, Siena, Italy) or with non-adjuvanted (AGRIPPAL, Chiron) trivalent influenza vaccine.

DESIGN

Blood samples, collected before and after vaccination, were analysed for the presence of antibodies against the vaccine antigens, for number of CD4+ T lymphocytes and HIV-1 RNA levels.

RESULTS

Forty-four volunteers received FLUAD and 40 AGRIPPAL influenza vaccine. Thirty days after vaccination both adjuvanted and non-adjuvanted vaccines induced significant increases of anti-influenza virus antibodies. However, antibody titres found in volunteers receiving adjuvanted vaccine were in general significantly higher when compared with those found in the non-adjuvanted vaccine group. The requirements of the European Commission of influenza vaccine for a non-elderly adult population were always met by recipients of the adjuvanted vaccine, even in those with the lowest CD4+ cell counts (<200 cells/mmc). The subjects receiving the non-adjuvanted vaccine failed to met these requirements. The CD4+ T lymphocytes and plasma HIV-1 RNA levels remained stable in the long term, both in people receiving adjuvanted or non-adjuvanted vaccine.

CONCLUSION

MF59-adjuvanted influenza induced a significant higher immune responses as compared with conventional vaccine in HIV-seropositive HAART-treated patients. Both vaccines were safe regarding HIV RNA viral replication and loss of CD4+ T lymphocytes.

Modeling the effects of vaccination on chronically infected HIV-positive patients

T-cell activation plays a critical role in the initiation and propagation of HIV-1 infection and yet transient activation of the immune system is a normal response to immunization. While it is now considered wise to vaccinate HIV-1-positive patients, it is crucial to anticipate any lasting effects of vaccination on plasma HIV-1 RNA levels and on infected T-cell populations. We extend a simple dynamic model of HIV infection to include T-cell activation by vaccination. We show that the model can reproduce many but not all of the features of the post-tetanus immunization rise in viral load observed and reported on by Stanley et al. in 1966 ( 334:1222-1230). Amplitudes and approximate timing of postimmunization peak viral loads were matched in 10 of 12 cases; in patients with double postimmunization peaks of nearly equal amplitude the later peaks were matched. Furthermore, our simulations suggest that productively infected cell populations track postvaccination increases in plasma viral load, rising and falling in concert over a period of about 4 weeks, whereas chronically infected cells peak later and remain elevated over baseline levels for up to 6 weeks postvaccination.

Viral load response to a pneumococcal conjugate vaccine, polysaccharide vaccine or placebo among HIV-infected patients

We determined the HIV viral load in 66 adults randomly assigned to receive pneumococcal immunization with one or two doses of protein conjugate vaccine, one dose of polysaccharide vaccine, one dose of each, or placebo. Second doses were given 8 weeks after the first. Mean baseline viral load and CD4 cell count were 3.41 copies/ml (log10) and 457 cells/microl, respectively. We found no change in viral load during 24 weeks of follow-up for any vaccine or combination of vaccines or placebo.

Syncytium formation and HIV-1 replication are both accentuated by purified influenza and virus-associated neuraminidase

The degree of sialylation has been shown previously to modulate the process of human immunodeficiency virus type-1 (HIV-1) infection by affecting the interaction between the virus and CD4-expressing target cells. In the present study, we investigated whether HIV-1 replication cycle was affected by neuraminidase (NA) derived from the human influenza (flu) virus. We first demonstrate that the level of HIV-1-mediated syncytium formation was greatly enhanced in the presence of purified flu NA. Pretreatment of established monocytic and lymphocytic cell lines as well as primary mononuclear cells with purified flu NA augmented also the process of virus infection. A comparable up-regulating effect was observed when using several strains of UV-inactivated whole flu virus, thereby suggesting that virus-anchored NA enzymes positively modulate the HIV-1 life cycle. Furthermore, flu NA-mediated positive effect on HIV-1 biology was abrogated with zanamivir, a specific flu NA inhibitor. Our results provide a new model allowing the investigation of the potential benefit of using NA inhibitors in the treatment of HIV-1-infected patients suffering from coinfection with NA-bearing pathogens.

Genotypic analysis of plasma HIV-1 RNA after influenza vaccination of patients with previously undetectable viral loads

OBJECTIVE

In this study we evaluated the possibility that plasma viral load elevations secondary to influenza vaccination in HIV-1-seropositive individuals with previously undetectable viral loads (< 200 copies/ml) could develop resistance-bearing mutations in the viral reverse transcriptase (RT) and protease regions.

METHODS

Thirty-four patients with undetectable viral burdens on highly active antiretroviral therapy (HAART) were evaluated for elevations in plasma viral load 2 and 4 weeks post-influenza vaccination. Plasma from patients whose viral load increased after vaccination was subject to genotypic resistance analysis by the line probe assay (LiPA) to determine whether primary resistance-bearing mutations developed during this period and at follow-up. Stored plasma was used to evaluate whether RT or protease mutations existed pre-vaccination.

RESULTS

Seven out of 34 patients were found to experience elevations in their viral load after influenza vaccination. Two of the patients revealed evidence of primary RT or protease mutations not demonstrated in earlier pre-vaccination samples. One patient failed therapy after vaccination, and one patient revealed post-vaccination viral load elevations that eventually led to the progressive development of primary zidovudine mutations.

CONCLUSION

Evidence is presented that supports the contention that a small subset of patients who experience viral load elevations after influenza vaccination can develop mutational changes in the RT region of the viral genome either acutely or after a failure of the viral load to return to undetectable levels.

Safety, vaccine virus shedding and immunogenicity of trivalent, cold-adapted, live attenuated influenza vaccine administered to human immunodeficiency virus-infected and noninfected children

OBJECTIVE

To assess the safety of live, attenuated influenza vaccine (LAIV) administered to relatively asymptomatic or mildly symptomatic HIV-infected children and non-HIV-infected children.

METHODS

Twenty-five non-HIV and 24 HIV-infected children (CDC Class N or A1,2) were enrolled into this double blind, placebo-controlled study. Children were randomized within each HIV status group to one of two dosing regimens: Regimen 1, Dose 1 = LAIV, Dose 2 = placebo, Dose 3 = LAIV; or Regimen 2, Dose 1 = placebo, Dose 2 = LAIV, Dose 3 = LAIV. Study doses were separated by 28 to 35 days. Reactogenicity events within 10 days and adverse events within 28 to 35 days after each study dose were recorded. Blood HIV RNA concentrations, CD4 counts and CD4% were measured throughout the study on HIV-infected children. Quantitative influenza cultures were performed on nasal aspirates collected periodically from all children up to 28 to 35 days after each study dose. Influenza isolates were assessed for retention of the temperature-sensitive phenotype. Serum influenza HAI antibodies were measured before and after each LAIV vaccination.

RESULTS

No significant differences were found in rates of reactogenicity events and vaccine-related adverse events after placebo or the first dose of LAIV within each HIV status group, nor were differences found between HIV-infected and HIV-uninfected children after each dose of LAIV. Overall none of the HIV-infected children experienced a significant LAIV-related serious adverse event or influenza-like illness, making the one sided 95% CI of such a serious event occurring after LAIV 0 to 12%. No significant changes in geometric mean HIV RNA concentrations, CD4 counts or CD4% or prolonged or increased quantity of LAIV virus shedding occurred in HIV-infected children after receiving either dose of LAIV. All recovered influenza isolates retained the temperature-sensitive phenotype. After two doses of LAIV, 83% of the non-HIV-infected and 77% of the HIV-infected children had a > or = 4-fold rise in influenza antibody to at least one of the three LAIV strains.

CONCLUSION

If relatively healthy HIV-infected children become exposed to LAIV inadvertently, then serious adverse outcomes would not be expected to occur frequently.

Contribution of immune activation to the pathogenesis and transmission of human immunodeficiency virus type 1 infection

The life cycle of human immunodeficiency virus type 1 (HIV-1) is intricately related to the activation state of the host cells supporting viral replication. Although cellular activation is essential to mount an effective host immune response to invading pathogens, paradoxically the marked systemic immune activation that accompanies HIV-1 infection in vivo may play an important role in sustaining phenomenal rates of HIV-1 replication in infected persons. Moreover, by inducing CD4+ cell loss by apoptosis, immune activation may further be central to the increased rate of CD4+ cell turnover and eventual development of CD4+ lymphocytopenia. In addition to HIV-1-induced immune activation, exogenous immune stimuli such as opportunistic infections may further impact the rate of HIV-1 replication systemically or at localized anatomical sites. Such stimuli may also lead to genotypic and phenotypic changes in the virus pool. Together, these various immunological effects on the biology of HIV-1 may potentially enhance disease progression in HIV-infected persons and may ultimately outweigh the beneficial aspects of antiviral immune responses. This may be particularly important for those living in developing countries, where there is little or no access to antiretroviral drugs and where frequent exposure to pathogenic organisms sustains a chronically heightened state of immune activation. Moreover, immune activation associated with sexually transmitted diseases, chorioamnionitis, and mastitis may have important local effects on HIV-1 replication that may increase the risk of sexual or mother-to-child transmission of HIV-1. The aim of this paper is to provide a broad review of the interrelationship between immune activation and the immunopathogenesis, transmission, progression, and treatment of HIV-1 infection in vivo.

Influenza A among patients with human immunodeficiency virus: an outbreak of infection at a residential facility in New York City

Although annual influenza vaccination is recommended for persons who are infected with human immunodeficiency virus (HIV), data are limited regarding the epidemiology of influenza or the effectiveness of influenza vaccination in this population. We investigated a 1996 outbreak of infection with influenza A at a residential facility for persons with AIDS. We interviewed 118 residents and employees, reviewed 65 resident medical records, and collected serum samples for measurement of influenza antibody titers. After controlling for history of smoking, influenza vaccination, and resident or employee status, in a multivariate model, HIV infection was not statistically associated with influenza-like illness (ILI). Symptoms and duration of ILI were similar for most HIV-infected and HIV-uninfected persons. However, 8 (21.1%) of 38 HIV-infected persons with ILI (vs. none of 15 HIV-uninfected persons) were either hospitalized, evaluated in an emergency room, or had ILI lasting > or = 14 days (P=.06). Vaccination effectiveness (VE) was similar for HIV-infected and HIV-uninfected persons. Vaccination was most effective among HIV-infected persons with CD4 cell counts of >100 cells/microL (VE, 65%; 95% CI, 36%--81%) or HIV type 1 virus load of <30,000 copies/mL (VE, 52%; 95% CI, 11%--75%). Providers should continue to offer influenza vaccination to HIV-infected persons.

Influenza and human immunodeficiency virus infection: absence of HIV progression after acute influenza infection

Influenza is a major cause of morbidity for people with significant underlying disease, but the impact of influenza on people infected with human immunodeficiency virus (HIV) remains unclear. We studied a population of HIV-infected adults during the 1998-1999 influenza season to see whether influenza had any adverse effects on the course of HIV infection. During 5 months of follow-up, we found no unique clinical manifestations or negative impact on CD4(+) cell count, virus load, or clinical progression of HIV disease. Although half of our cohort received antibiotic therapy, none received specific anti-influenza therapy and none required hospitalization. Acute influenza does not appear to be a risk for progression of HIV disease.

Effect of influenza vaccination on disease progression among HIV-infected persons

OBJECTIVE

To describe the effect of influenza vaccination on long-term change in CD4 count and HIV RNA level, and on progression to AIDS or death.

DESIGN AND SETTING

A longitudinal medical record review set in 113 medical clinics in 10 United States cities.

PATIENTS

A total of 36,050 HIV-infected persons aged > or = 13 years in care for HIV infection.

MAIN OUTCOME MEASURES

Change in CD4 count and HIV RNA level at follow-up (3-12 months after vaccination); hazard ratios (HR) for association of influenza vaccine with progression from baseline CD4 or HIV RNA level to AIDS and to death.

RESULTS

The median CD4 count among all persons decreased 28 cells/year during follow-up, with no difference in change in CD4 count between the 8007 (40%) vaccinated (median = 6 months, vaccine to follow-up CD4 count) and the 11,794 unvaccinated persons. In a viral load subanalysis, median HIV RNA level decreased 90 copies/ml per year among all persons during follow-up; decreases were not different between vaccinated and unvaccinated persons (median = 7 months, vaccine to follow-up HIV RNA level determination). Influenza vaccination was weakly associated with decreased risk of progression to clinical AIDS [HR 0.93; 95% confidence interval (CI), 0.87-0.99], but not associated with time to death (HR, 0.97; CI, 0.93-1.01).

CONCLUSIONS

No negative long-term effect of influenza vaccination on CD4 counts, HIV RNA levels, or progression to AIDS or death was found in this HIV-infected population. These data suggest that physicians should not withhold influenza vaccine because of concerns about long-term detrimental effects of increased viral replication.

Effect of clinical events on plasma HIV-1 RNA levels in persons with CD4+ T-lymphocyte counts of more than 500 x 10(6) cells/l

OBJECTIVE

Immune stimulation of CD4 lymphocytes is thought to enhance HIV-1 replication in vivo. Therefore, we sought to define the impact of clinical events identified as putative immune activators on the variability of plasma HIV-1 RNA levels in persons with CD4 cell counts greater than 500 x 10(6) cells/l.

DESIGN

We prospectively recorded clinical events and measured plasma HIV-1 RNA levels weekly for 24 weeks in 16 HIV-1-infected adults who were not receiving antiretroviral therapy and who had CD4 cell counts greater than 500 x 10(6) cells/l.

METHODS

Standard weekly interviews were conducted to capture potential immune activators (e.g., infections, immunizations, and allergic reactions). All plasma HIV-1 RNA levels were measured using the Amplicor HIV-1 Monitor assay (Roche Diagnostics, Branchburg, New Jersey, USA) according to the manufacturer's instructions.

RESULTS

Participants had remarkably stable viral loads during the 6 month study period. Infections were significantly more frequent during the 7 days prior to individual HIV-1 RNA measurements that exceeded the assay variation thresholds determined for this study (+/- 0.324 log) than during the comparable time periods preceding stable measurements (P = 0.023). As a group, the eight participants who had one to four HIV-1 RNA measurements that exceeded the thresholds experienced more infections and declining CD4 cell counts over the study course compared to the eight participants whose measurements all fell within the thresholds (P = 0.058 and 0.053 respectively).

CONCLUSIONS

Our study suggests that in untreated HIV-1-infected persons with CD4 cell count greater than 500 x 10(6) cells/l, viral load is generally quite stable, although acute minor infections are associated with transient fluctuations generally lasting no more than 1 week.

Early changes in peripheral blood T cell subsets induced by antiretroviral treatment of human immunodeficiency virus-1 positive individuals

Human immunodeficiency virus (HIV)-1 infection causes a gradual decline in peripheral blood CD4+ T cells. Shortly after the primary infection, an expansion of the activated memory CD8+ T-cell pool is also observed paralleling increased levels of plasma viraemia. In the present study we investigated the immediate effects of zidovudine therapy on peripheral blood T-cell subsets during the first 3 weeks of therapy in a group of HIV-1 positive individuals receiving influenza vaccine. HIV-1 positive individuals who received vaccine, but no treatment, were included as controls. Both the number of CD4+ and CD8+ T cells increased during the first week of therapy in parallel with a decline in plasma viraemia. The majority of CD4+ T cells contributing to this expansion expressed CD28, CD45RO and Fas, whereas the expanded CD8+ T cells were predominantly CD28-, CD45RO+, CD38+, Fas+ and Fas+ (CD95). We propose that the increase in the number of activated memory T cells observed in peripheral blood immediately after the onset of antiretroviral treatment is most likely caused by the redistribution of cells from various lymphoid organs in response to decreased levels of viral load in these compartments. The degree of T-cell redistribution is probably dependent on the magnitude of virus suppression.

Pertussis immunization in HIV-1-infected infants: a model to assess the effects of repeated T cell-dependent antigen administrations on HIV-1 progression. Italian Register for HIV infection in children

Several data evidence that HIV-1 replication may increase in temporal association with immunizations, raising concerns on potential negative effects of vaccinations on HIV-1 progression. Among patients prospectively followed by the "Italian Register for HIV infection in children", we evaluated, using the Cox-Mantel method, conditional probabilities of progressing to CDC clinical categories 'B' or 'C', and immunological categories '2' or '3' in 88 children immunized against pertussis and 244 non-immunized. No selection criteria were followed in vaccinating children. No significant differences were observed between the two groups. The lack of a significant impact on clinical and immunological deterioration by the repeated administrations of a T cell-dependent vaccine endorses the current recommendations for routine immunizations in HIV-1-infected children.

Vaccination and HIV: a review of the literature

People with HIV are at risk for a variety of infections both at home and abroad. Recent studies have reported conflicting data concerning potential harmful effects following several inactivated vaccines. Antigenic stimulation by vaccines designed to prevent secondary infections may promote HIV-1 replication in certain patients. In HIV-positive subjects, immune response worsens with progression of the HIV infection. When vaccination is considered, administration of the vaccine must be performed as early as possible in the course of HIV infection because an HIV-infected patient's response to inactivated vaccines is closely related to HIV infection stage. A minority of subjects have a protective antibody response to vaccination. Consequently, specific antibody titers should be measured after vaccination to ensure immune protection. Immune response is improved by highly active antiretroviral therapy. Some live attenuated vaccines are considered as beneficial in some specific indications and if administered in the early stages of AIDS. However, viral load variations following administration of live attenuated vaccines have not been studied yet.

Influenza vaccines: present and future

Immunization is the most feasible method for preventing influenza. Vaccination against influenza is recommended for everyone 65 years of age and older and for persons less than 65 years of age who are at risk for developing complications of influenza. Immune correlates of protection have been established, and a global network is in place to monitor the appearance and circulation of antigenic variants of influenza viruses, as well as the appearance of novel subtypes of influenza A. Antigenic and genetic analyses of circulating viruses and testing of serum from vaccine recipients guide vaccine composition updates. The efficacy of influenza vaccines depends in part on the closeness of the antigenic match between the vaccine strain and the epidemic strain. Currently licensed influenza vaccines are trivalent, formalin-inactivated, egg-derived vaccines; their efficacy ranges from 70 to 90% in young, healthy populations when there is a close antigenic match between vaccine strains and epidemic strains. Development of intranasally administered alternative vaccines and improvement of the existing vaccine are areas of active research. A trivalent, ca live vaccine is the most promising LAIV candidate. In a field trial, efficacy rates of LAIV in young children were 96% against influenza A (H3N2) and 91% against influenza B. However, few data are available to compare this formulation of the trivalent ca live vaccine with the trivalent, inactivated vaccine. Influenza vaccine recommendations will most likely be revised on licensure of LAIV; each vaccine may offer distinct advantages in specific populations.

Monocytes modulate enhancement of HIV-1 replication by Mycobacterium tuberculosis

To investigate the effects of Mycobacterium tuberculosis on HIV-1 replication, peripheral blood mononuclear cells (PBMC) of bacille Calmette-Guerin (BCG)-vaccinated donors and non-BCG-vaccinated donors were infected in vitro with a lymphotropic isolate of HIV-1 and cultured in the presence of purified protein derivative (PPD). Addition of PPD resulted in enhanced HIV-1 replication and lymphoproliferation in BCG-vaccinated donor PBMC, while PPD had no such effects in control PBMC. HIV-1 replication increased even more when monocytes were removed from PBMC, while lymphoproliferation was decreased. High percentages of monocytes were associated with a decreased HIV-1 replication and proliferation that could not be reversed by addition of antibodies against the cytokines IL-1, transforming growth factor-beta (TGF-beta) or indomethacin. PPD stimulates PBMC to release IL-10, a cytokine known to down-regulate proliferation and HIV-1 replication. PPD-induced effects on proliferation as well as HIV-1 replication could be partially blocked by adding a monoclonal antibody against MHC class II molecules, suggesting that part of the mechanism of PPD-induced enhancement is T memory cell activation.

Comparison of neutralizing and hemagglutination-inhibiting antibody responses to influenza A virus vaccination of human immunodeficiency virus-infected individuals

A neutralization enzyme immunoassay (N-EIA) was used to determine the neutralizing serum antibody titers to influenza A/Taiwan/1/86 (H1N1) and Beijing/353/89 (H3N2) viruses after vaccination of 51 human immunodeficiency virus (HIV) type 1-infected individuals and 10 healthy noninfected controls against influenza virus infection. Overall, the N-EIA titers correlated well with the hemagglutination-inhibition (HAI) titers that were observed in the same samples in a previous study (F. P. Kroon, J. T. van Dissel, J. C. de Jong, and R. van Furth, AIDS 8:469-476,1994). The N-EIA appeared to be more sensitive than the HAI test. Significantly more fourfold or higher rises in N-EIA titer and higher mean N-EIA titers occurred in HIV-infected individuals with > or =200 CD4+ cells per microl than in those with <200 CD4+ cells per microl.

Immunologic and virologic evaluation after influenza vaccination of HIV-1-infected patients

OBJECTIVE

The present study was designed to determine the effect of immune activation, achieved by influenza vaccination, on plasma HIV RNA levels and immunological parameters including CD4 cell levels, antigen-stimulated T-cell function and apoptotic death of peripheral blood mononuclear cells.

DESIGN AND METHODS

Thirty-four HIV-infected individuals and nine uninfected controls were immunized with influenza vaccine and blood was collected at weeks 0, 2, 4 and 16. Plasma was isolated and used for HIV RNA and influenza-specific antibody qualifications. CD4 cell counts, activation and maturation markers of T-lymphocyte subsets were determined by flow cytometry. In vitro T-helper responses, spontaneous- and activation-induced cell death assays were also performed.

RESULTS

Influenza-specific humoral and cellular immune responses correlated with CD4 count. Only in patients with CD4 counts > 300 x 10(6)/l there was a modest increase in T-cell responses to influenza virus, which was less than control subjects, observed after vaccination. Immunization had no significant effect on CD4 counts or plasma viral levels in the HIV-positive patients. Baseline apoptosis inversely correlated with CD4 counts and directly correlated with viral load. Activation-induced apoptosis did not change appreciably after vaccination and spontaneous apoptosis increased only in the < 300 CD4 group.

CONCLUSION

These results indicate that immune stimulation resulting from influenza vaccination did not significantly change the levels of plasma virus, CD4 cell counts, or activation-induced apoptosis in HIV-infected individuals, although an increase in the T-cell response to influenza and spontaneous apoptosis was observed in the > 300 and < 300 CD4 groups, respectively.

Community respiratory viruses in individuals with human immunodeficiency virus infection

Respiratory viruses, particularly influenza viruses, respiratory syncytial virus (RSV), parainfluenza viruses, and adenoviruses, are ubiquitous pathogens among humans, especially among young children. However, relatively little is known about the impact of these common infections on individuals with the human immunodeficiency virus (HIV). A review of the literature identifies three key areas that need further exploration. First, moderate-to-severe and even fatal lower respiratory viral illnesses in HIV-infected individuals have been reported. In general, the clinical presentation of these respiratory viral infections in persons with HIV infection is similar to their presentation in individuals without HIV infection. The major exception is the occurrence of fulminant, and often fatal, disseminated adenovirus infection in adults and children with HIV disease. Despite these reports, no information is available regarding the frequency of moderate-to-severe respiratory viral illnesses in individuals with HIV infection. Epidemiologic studies of respiratory viral illnesses in cohorts of HIV-infected adults and children are needed. Second, prolonged shedding of respiratory viruses for weeks and even months has been documented in HIV-infected adults and children. The frequency of prolonged shedding in this population has not been well defined, but data from a small newborn cohort study suggest that, at least for RSV, prolonged shedding is common. Prolonged respiratory viral shedding has implications for infection control in medical facilities where HIV-infected individuals are treated and in nursing homes, child care centers, and group foster homes that provide care for HIV-infected individuals. Therapies to help eliminate these chronic viral infections should be explored. Finally, indirect evidence suggests that respiratory viral infection may result in changes in HIV replication and, theoretically, HIV disease progression. Increased HIV-1 replication has been demonstrated in vitro in T lymphoma cells exposed to genetic material from adenovirus. Increased HIV replication in peripheral blood from adults following inactivated influenza vaccination has been reported. The impact of natural respiratory viral infection (and perhaps vaccination against these pathogens) on HIV replication and disease progression will be an important area of study.