Intestinal Secretory Immunoglobulin A Response to Enteroaggregative Escherichia coli in Travelers with Diarrhea

We examined stool samples from travelers for secretory immunoglobulin A (sIgA) to enteroaggregative Escherichia coli (EAEC) during episodes of acute diarrhea. Ten paired samples from 10 patients with diarrhea caused by EAEC were examined for the presence of specific sIgA by dot blot and Western blot immunoassays. Five samples were positive by dot blotting, and two samples were positive by Western blotting.     

Slow Human Immunodeficiency Virus (HIV) Infectivity Correlated with Low HIV Coreceptor Levels

The absolute number of CD4⁺ lymphocytes in blood is prognostic for disease progression, yet the cell surface density of CD4 receptors or chemokine receptors on a single cell has not previously been found to be predictive of human immunodeficiency virus (HIV) infectivity outcome. It has recently been shown that human leukocyte elastase (HLE) and its ligand α₁ proteinase inhibitor (α₁PI; α₁ antitrypsin) act as HIV fusion cofactors. The present study shows that decreased HIV infectivity is significantly correlated with decreased cell surface density of HLE but not with decreased CD4 nor chemokine receptors. In vitro HIV infectivity outcome in this study was predicted by the surface density of HLE on mononuclear phagocytes but not on lymphocytes. The set point HLE surface density was in part determined by α₁PI. Decreased circulating α₁PI was correlated with increased cell surface HLE and with increased HIV infectivity. The correlation of HIV infectivity outcome with surface HLE and circulating α₁PI supports the utility of these HIV cofactors in diagnostic analysis and therapeutic intervention.     

Human Immunodeficiency Virus (HIV) Infection of Human Macrophages Is Increased by Dopamine : A Bridge between HIV-Associated Neurologic Disorders and Drug Abuse

The prevalence of human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) that result from HIV infection of the central nervous system is increasing. Macrophages, the primary target for HIV within the central nervous system, play a central role in HIV-induced neuropathogenesis. Drug abuse exacerbates HAND, but the mechanism(s) by which this increased neuropathology results in more severe forms of HAND in HIV-infected drug abusers is unclear. The addictive and reinforcing effects of many drugs of abuse, such as cocaine and methamphetamine, are mediated by increased extracellular dopamine in the brain. We propose a novel mechanism by which drugs of abuse intensify HIV neuropathogenesis through direct effects of the neurotransmitter dopamine on HIV infection of macrophages. We found that macrophages express dopamine receptors 1 and 2, and dopamine activates macrophages by increasing ERK 1 phosphorylation. Our results demonstrate for the first time that dopamine increases HIV replication in human macrophages and that the mechanism by which dopamine mediates this change is by increasing the total number of HIV-infected macrophages. This increase in HIV replication is mediated by activation of dopamine receptor 2. These findings suggest a common mechanism by which drugs of abuse enhance HIV replication in macrophages and indicate that the drug abuse-heightened levels of central nervous system dopamine could increase viral replication, thereby accelerating the development of HAND.Human immunodeficiency virus (HIV) enters the central nervous system (CNS) soon after initial infection,¹ resulting in ongoing inflammation and neurological damage that leads to the development of HIV-associated neurocognitive disorders (HAND) in as many as 50% of infected individuals.^2,3 The prevalence of these complications is increasing despite the advent of antiretroviral therapy, due to the longer lifespan of infected individuals on antiretroviral therapies⁴ and the poor ability of most antiretroviral drugs to penetrate the blood-brain barrier.^5,6 HIV is thought to enter the brain through the transmigration of infected monocytes across the blood-brain barrier.^7,8,9,10 Within the CNS, macrophages are the primary source of HIV and the virus spreads primarily through infection of brain macrophages and microglia.^11,12 Infected macrophages produce numerous factors that are neurotoxic and contribute to the neurological damage that occurs in HIV-infected individuals.^13,14,15 Thus, HIV infection and replication within CNS macrophages plays a central role in the development of HANDs.The incidence and severity of HAND are exacerbated by drugs of abuse, such as the psychostimulants cocaine and methamphetamine,^16,17,18,19 which have been shown to increase both HIV neuropathogenesis and viral replication.^{20,21,22,23,24} However, the mechanism(s) by which drugs of abuse enhance HIV-related neuropathologies are not well understood. Dopamine (DA), a neurotransmitter involved in the control of locomotion, cognition, positive reinforcement, and neuroendocrine secretion,²⁵ is central to the action of drugs of abuse. Psychostimulants such as cocaine and methamphetamine exert addictive and reinforcing effects through elevation of extracellular DA levels in the CNS.^{26,27,28,29,30} The use of both cocaine and methamphetamine generates extracellular CNS dopamine levels far higher than those found in the brains of non-drug-abusers.^{26,31,32,33,34,35,36}Dopamine acts through dopamine receptors, which are members of the G-protein coupled seven transmembrane domain family of receptors. Dopamine receptors (DRs) are divided into two subtypes designated D1-like DRs, comprised of dopamine receptor 1 (D1R) and D5R, and D2-like DRs, comprised of D2R, D3R, and D4R.²⁵ Classically, DRs have been studied on neurons, but DR expression has also been reported in several types of peripheral blood leukocytes, including T lymphocytes and monocytes.^37,38,39 Dopamine receptors have been shown to modulate the immune function of T lymphocytes.^25,40,41 A recent study showed D1R on human macrophages,²⁴ but the expression of other DRs and the functions of DRs in this cell type have not been well characterized.In studies with simian immunodeficiency virus-infected macaques, injection with or oral administration of L-DOPA, a DA precursor that crosses the blood-brain barrier, or selegiline, a blocker of DA breakdown by monoamine oxidase, resulted in increased levels of simian immunodeficiency virus in the CNS.^42,43 In addition, infected macaques exhibited an increased incidence of simian immunodeficiency virus encephalitis and induction of a spongiform polioencephalopathy in dopaminergic regions of the CNS.^42,43 These studies suggest that the enhanced extracellular DA elicited by use of drugs like cocaine and methamphetamine could be sufficient to increase HIV replication in the CNS and exacerbate HIV neuropathogenesis. Macrophages play a central role in the development of HIV-induced neuropathology. Thus, examination of DA modulation of HIV infection of macrophages, as well as the characterization of intracellular signaling pathways that are involved in the DA-mediated increase in HIV infectivity, are important to the identification of mechanisms by which drugs of abuse enhance the development of HAND.This report demonstrates that primary human monocyte-derived macrophages (MDMs) inoculated with HIV in the presence of DA exhibit increased levels of viral replication when compared with MDMs inoculated with HIV in the absence of DA. The DA-induced increase in viral replication correlated with an increase in the percentage of MDMs infected with HIV. HIV infection in the presence of the D2R agonist, quinpirole, increased viral replication similarly to DA, while infection in the presence of the D1R agonist, SKF 82958, did not alter HIV replication, suggesting that D2R is involved in the DA-mediated increase in HIV replication. The data also confirm that uninfected MDMs expressed both D1R and D2R on the cell surface and show that endogenous macrophage D2R was active by demonstrating that DA induced extracellular signal regulated kinase 1 (ERK 1) phosphorylation in macrophages through D2R. These results suggest that dopamine-induced increases in HIV replication in macrophages may be an important mechanism by which specific drugs of abuse, characterized by their ability to increase extracellular DA levels in the CNS, exacerbate the neuropathogenesis of HIV infection.     

Immunity to Human Immunodeficiency Virus (HIV) in Children with Chronic HIV Infection Receiving Highly Active Antiretroviral Therapy

Our objective was to describe the CD4-mediated human immunodeficiency virus (HIV)-specific cell-mediated immunity (CMI) and its virologic and immunologic correlates in children with chronic HIV infection on highly active antiretroviral therapy (HAART). Twelve HIV-infected children on stable antiretroviral therapy with a median level of CD4⁺ lymphocytes (CD4%) of 25.5% and a median viral load (VL) of 786 HIV RNA copies/ml were enrolled in this study. Nine of these children were also cytomegalovirus (CMV) seropositive. Blood mononuclear cells, stimulated with HIV and CMV antigens, were used to measure lymphocyte proliferation and to enumerate gamma interferon (IFN-γ)-producing CD4⁺ cells. HIV CMI and CMV CMI were detected in similar proportions of patients and correlated with each other, although the HIV responses were less robust. HIV lymphocyte proliferation significantly increased with lower HIV VL and showed a trend to increase with higher CD4% and longer time on HAART. The in vitro IFN-γ response to HIV or CMV was not affected by CD4%, VL, or HAART. Pediatric patients with established HIV infection on HAART frequently exhibit HIV CMI despite undetectable HIV replication. We concluded that the association between HIV CMI and CMV CMI indicates that the same factors govern responsiveness to either antigen.     

Human Immunodeficiency Virus (HIV) Risk Among the Seriously Mentally III

Seriously mentally ill adults are at high risk for human immunodeficiency virus (HIV) infection. We review the empirical literature that documents this elevated risk in psychiatric patients and identify factors that have been associated with enhanced risk. Our review indicates five characteristics related to HIV risk in psychiatric populations: psychopathology severity and symptomatology, substance abuse proximal to sexual behavior, misinformation about HIV transmission, perceptions of invulnerability, and sttuational, lifestyle factors. Understanding these characteristics can lead to improved HIV preventive intervention models. However, we also note that studies have been limited by unreliable psychiatric diagnoses and sampling constraints. We conclude with suggestions for research, practice, and prevention based on findings in the empirical literature and theories of HIV risk reduction.     

Bilateral peripheral facial palsy in a patient with Human Immunodeficiency Virus (HIV) infection

Neurological complications are important causes of morbidity and mortality in patients with human immunodeficiency virus (HIV) infection. They can occur at any stage of the disease and can affect any level of the central or peripheral nervous systems. In the literature, several cases of HIV-associated facial paralysis have been reported; however, bilateral facial palsy is rarely reported. In this paper, we present the first case in Korea, of a bilateral facial palsy occurring as the first clinical manifestation of HIV infection.     

Intestinal immune response of volunteers ingesting a strain of enteroadherent (HEp-2 cell-adherent) Escherichia coli.

Enteroadherent Escherichia coli (EAEC) strains identified by adherence to HEp-2 tissue culture cells have been incriminated epidemiologically as important etiologic agents of diarrheal disease in both adult travelers and children in developing countries. One strain, JM 221, with no recognized E. coli virulence characteristics other than adherence to HEp-2 cells, caused diarrhea in 5 of 16 volunteers ingesting it. We studied the secretory immunoglobulin A (sIgA) responses to EAEC JM 221 of five volunteers with diarrhea and five volunteers who remained healthy after challenge. sIgA was extracted from stools obtained prechallenge and 7 days postchallenge. Total sIgA was standardized for all specimens. Specific sIgA titers were determined by dot blotting with the following JM 221 antigens: water-extractable surface antigens, whole cells, lipopolysaccharides, and outer membrane proteins. All five subjects who became ill had fourfold or greater rises in titers against each of the four antigens. The five subjects who remained healthy following challenge did not exhibit significant rises in titers to any JM 221 antigens, but their mean titers were significantly higher than the mean prechallenge titers of the volunteers with diarrhea, suggesting that high intestinal sIgA titers may be protective. The significant increases in intestinal antibody against JM 221 in the subjects who became ill is further evidence of the enteropathogenicity of EAEC strains.     

Molecular Confirmation of Human Immunodeficiency Virus (HIV) Type 2 in HIV-Seropositive Subjects in South India

Nested PCRs for human immunodeficiency virus type 1 (HIV-1) and HIV-2 were compared with immunoblot test results. Twelve of 13 immunoblot-positive HIV-2 samples were positive by PCR. There were five INNO-LIA (Innogenetics, Zwijnaarde, Belgium) and/or HIVBLOT 2.2 (Genelabs, Singapore) samples that tested positive for dual infection. HIV-1 PCR was positive in all samples, while HIV-2 PCR was positive in two and RIBA (Chiron Corporation, San Diego, Calif.) was positive for HIV-2 in three samples. Thus the prevalence of HIV-2 is accurately estimated by the use of immunoblotting, but that of HIV-1 and -2 dual infection may be overestimated.     

Complement Activation is Associated with the Presence of Specific Human Immunodeficiency Virus (HIV)-Anti-HIV Immune Complexes in Patients with Acquired Immunodeficiency Syndrome-Related Complex or Lymphoadenopathy Syndrome

The complement system was examined in a group of eight patients (six with lymphoadenopathy syndrome (LAS); two with acquired immunodeficiency syndrome (AIDS)-related complex (ARC], who were found to be human immunodeficiency virus (HIV)-positive, for the presence of specific HIV-anti-HIV complexes. A significant impairment of the classical and/or alternative pathway was found associated with the presence of cleavage fragments of C3 and/or B and a significant reduction in the complement factors studied. Ultracentrifugation fractions of serum samples obtained from one of the patients were assessed for the detection of specific HIV-anti-HIV (GP41-anti-GP41) complexes and were incubated with normal human serum to determine their complement activation capacity. A clear complement activation was found with the fraction in which a clear peak of HIV-anti-HIV (GP41-anti-GP41) immune complexes was present. The results demonstrate that specific immune complexes and complement activation are sometimes concomitantly present in patients with AIDS-related disease and that specific immune complexes may be one of the causal factors of the pathogenesis of complement activation in these patients. Possible consequences for the severe immune regulation with relevance to the dramatic failure in treating the virus effectively are discussed.     

Escherichia coli adherence to HEp-2 cells with prefixed cells.

We describe a new method which uses cold absolute methanol-prefixed cells for adherence of enteropathogenic Escherichia coli to HEp-2 cells. We found that a method using bacteria grown in Penassay broth to 10(6) to 10(7) CFU/ml and incubated with prefixed cells for 3 h at 37 degrees C, showed 100% sensitivity and specificity against a method using live cells.     

Response to Standard Syphilis Treatment in Patients Infected with the Human Immunodeficiency Virus

 In a study designed to evaluate the efficacy of penicillin in HIV-infected patients with syphilis and to determine the clinical and laboratory responses after treatment, 13 patients with HIV infection and syphilis were assessed at enrollment and at the last follow-up examination (median time of 21 months). The Venereal Diseases Research Laboratory (VDRL) test, the Treponema pallidum hemaglutination test, and leukocyte counts in cerebrospinal fluid were evaluated both at enrollment and at the last follow-up visit, and the polymerase chain reaction for Treponema pallidum DNA and the rabbit infectivity test were performed on cerebrospinal fluid samples at the last follow-up visit. Primary syphilis was confirmed in four patients, latent syphilis in five, and neurosyphilis in four. After penicillin treatment, all patients were asymptomatic. The serum rapid plasma reagin test became negative in five patients, and titers declined in eight. The VDRL test, Treponema pallidum DNA, and the rabbit infectivity test were negative in all 13 patients. Except for one patient whose serological titer was slow to decline, all patients had good clinical and serological responses to penicillin. In certain settings, factors other than penicillin treatment failure should be considered in HIV-infected patients with suspected relapse of syphilis.     

HLA typing in heavily transfused haemophiliacs with or without antibodies against Human Immunodeficiency Virus (HIV)

HLA-A, B, DR antigens were determined in 46 patients, heavily transfused with blood products. Patients were 44 haemophiliacs, one case of afibrinogenemia and one case of von Willebrand's disease. Thirty-three patients had HIV antibodies. No significant difference for HLA antigen frequencies was observed in haemophiliacs with or without HIV antibodies, nor between haemophiliacs and a control population.     

Deficient Antibody-Dependent Cellular Cytotoxicity against Human Immunodeficiency Virus (HIV)-Expressing Target Cells in Perinatal HIV Infection

Peripheral blood mononuclear cells (PBMC) of human immunodeficiency virus (HIV)-infected children, age-matched HIV-seronegative controls, and HIV-infected asymptomatic and symptomatic adults were compared for their ability to mediate antibody-dependent cellular cytotoxicity (ADCC) and natural killer (NK) cell-mediated cytotoxicity against target cells expressing HIV or herpes simplex virus (HSV) antigens. Target cells consisted of CD4 lymphocytes purified from PBMC of HIV-seronegative adults and incubated with the IIIB strain of HIV, HUT78 cells chronically infected with IIIB, and HSV-infected human fibroblasts. PBMC of asymptomatic HIV-infected adults were generally able to lyse CD4 cells expressing HIV antigens. Direct correlation was found between the magnitude of lysis and absolute CD4 cell counts in these individuals. In contrast to these results, PBMC from HIV-infected children were generally unable to lyse IIIB-expressing CD4 cells, regardless of the children’s clinical status, age, or absolute CD4 cell counts. Cells from HIV-seronegative adults and children did not directly lyse these target cells either but, in contrast to cells of HIV-seropositive children, were able to mediate cell lysis when serum from an HIV-seropositive adult was added. However, effector cells from these HIV-infected children were able to mediate both ADCC against HSV-infected fibroblasts and NK cell-mediated cytotoxicity against IIIB-infected HUT78 cells. Reduced ability of PBMC from vertically HIV-infected children to mediate ADCC against HIV antigen-expressing CD4 cells may contribute to rapid progression to AIDS.     

Immunological Changes in Human Immunodeficiency Virus (HIV)-Infected Individuals During HIV-Specific Protease Inhibitor Treatment

The present study examines the influence of effective anti-retroviral treatment on immune function, evaluated by a broad array of immunological tests. We followed 12 individuals infected with human immunodeficiency virus (HIV) for 6 months after initiation of combination anti-retroviral treatment including a protease inhibitor. Unstimulated and pokeweed mitogen (PWM)-, interleukin (IL)-2- and phytohaemagglutinin (PHA)-stimulated lymphocyte proliferative responses increased during follow-up reaching average levels from 1.3-fold (PHA) to 3.7-fold (PWM) above baseline values. The total CD4+ lymphocyte count increased mainly due to increases in numbers of CD4+ CD28+ and CD4+ CD45RO+ cells, whereas increases in numbers of CD4+ CD45RA+ cells contributed little to the increase in CD4+ cell count. The total cytotoxic T-cell (CTL) killing of autologous B cells infected with HIV-encoding recombinant Vaccinia virus was increased after 3-6 months, whereas the specific HIV-directed CTL activity and the concentration and lytic activity of natural killer (NK) cells were unchanged during follow-up. These results demonstrate that the initiation of a treatment including an HIV protease inhibitor is followed by an increase in lymphocyte proliferation and lymphocyte-mediated cytotoxicity. However, unchanged levels of specific HIV CTL and NK cell activity warn us that not all measures of immune function may respond simultaneously to anti-retroviral treatment.     

Enhancement of Human Immunodeficiency Virus (HIV) Replication in Human Monocytes by Low Titres of Anti-HIV Antibodies in Vitro

Low concentrations of serum obtained from a patient with acquired immunodeficiency syndrome (AIDS) enhanced the replication of human immunodeficiency virus type 1 (HIV-1) in a particular subclone of the CD-4-positive monocytoid cell line U937 clone 2. Cells of this subclone have a high expression of Fc receptors and a considerable degree of Fc-mediated phagocytic activity. IgG purified from the serum was also able to enhance the replication. These results indicate that low concentrations of human anti-HIV antibody may enhance HIV replication on human monocyte-macrophages. Furthermore, two mouse IgG1 monoclonal antibodies against gp120, the envelope glycoprotein of HIV-1, also induced enhancement at low concentrations. The binding of radiolabelled gp120 to the cells was increased at the same low concentrations. Antibodies against envelope glycoproteins may cause enhancement of HIV infection. Both normal and enhanced replication of HIV were completely inhibited by the masking of the binding site of CD4 molecules with F(ab')2 fragments of anti-CD4 antibody. Moreover, CD4-positive, Fc gamma RI-negative K562 cells and mouse macrophages failed to show any infection in the presence of antibody. These results suggest that CD4 molecules on the cell surface are necessary to cause enhancement of infection of HIV on monocyte-macrophages.     

Hepatitis B Virus (HBV) Mutations Associated with Resistance to Lamivudine in Patients Coinfected with HBV and Human Immunodeficiency Virus

Mutations associated with hepatitis B virus (HBV) resistance to lamivudine have not been extensively addressed in human immunodeficiency virus (HIV)-HBV coinfection. We have studied the HBV polymerase sequences from nine coinfected patients who experienced HBV recurrence while under lamivudine treatment. In seven of these nine patients, Met(550), belonging to the highly conserved YMDD motif, was mutated to Val and was associated with a substitution of Met for Leu(526) in each case. In the two remaining patients, we found a Met(550)-to-Ile change that was associated in only one case with a Leu(526)-to-Met mutation. No mutation was observed in three control patients not receiving lamivudine. This study demonstrates the emergence of particular genetic profiles in HBV-HIV-coinfected patients experiencing a loss of control of HBV infection despite high doses of lamivudine.