Journal of human virology最新文献

Objective: To identify a lipopolysaccharide (LPS) that retains the capacity to induce beta-chemokine secretion without the concomitant activation of pyrogenic cytokines.

Methods: LPS was extracted from strain MLK986 (mLPS), an htrB1::Tn10, msbB::ocam mutant of Escherichia coli that is defective for lipid A synthesis, and from wild-type parent E coli strains, W3110 (wtLPS). The capacity of these LPS preparations to induce tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), and macrophage inflammatory proteins 1 alpha (MIP-1 alpha) and MIP-1 beta was assessed using a human peripheral blood mononuclear cell (PBMC) activation assay.

Results: Stimulation of PBMCs with mLPS did not induce measurable levels of pyrogenic cytokines TNF-alpha and IL-1 beta, whereas wtLPS induced high levels of these cytokines. Furthermore, mLPS antagonized the induction of TNF-alpha secretion by wtLPS. Nonetheless, mLPS retained a discrete agonist activity that induced MIP-1 alpha and MIP-1 beta secretion by PBMCs. This latter agonist activity appears to be unique to mLPS, since two previously documented LPS antagonists, Rhodobacter sphaeroides diphosphoryl lipid A and synthetic lipid IVA, did not induce MIP-1 alpha and MIP-1 beta secretion. Furthermore, synthetic lipid IVA was an antagonist of MIP-1 alpha and MIP-1 beta induction by mLPS.

Conclusion: These results show that mLPS exhibits a novel bipartite activity, being an effective antagonist of TNF-alpha induction by wtLPS, while paradoxically being an agonist of MIP-1 alpha and MIP-1 beta secretion.

Objective: Cocultivation of the CD4+CD95+ T-cell line (MT4) with monocyte-derived macrophages (MDMs) infected with the HIV-1 resulted in costimulation of proliferation and apoptosis after 20 hours of contact. This study sought to determine whether tumor necrosis factor (TNF) produced by HIV-1-infected MDMs was involved in the costimulation of cell proliferation, the apoptotic pathway, or both.

Study design/methods: MT4 cells were cocultivated with infected or noninfected MDMs in the presence or absence of soluble TNF receptors (sTNFRs) or antagonistic anti-Fas antibody (ZB4). Cell proliferation was assessed by measuring thymidine incorporation. Apoptosis was monitored by using flow cytometry and enzyme-linked immunosorbent assay (ELISA).

Results: Thymidine incorporation was higher in cells cocultivated with HIV-infected or noninfected MDMs than it was in controls grown in culture medium. It also was higher in cells cocultivated with HIV-infected MDMs than it was in cells cocultivated with noninfected MDMs. sTNFRs blocked the increase of thymidine incorporation specifically induced by HIV-infected MDMs. They did not inhibit apoptosis at 20 hours. Cells recovered from cocultures involving HIV-infected or noninfected MDMs exhibited decreased sensitivity to apoptosis induced through the Fas receptor.

Conclusion: TNF produced by HIV-infected MDMs acts as an accessory T-cell growth factor that synergizes with an as yet unidentified growth-inducing signal or signals produced by HIV-infected and noninfected MDMs. Stimulation of cell proliferation by MDMs induces transient resistance to Fas-induced apoptosis.

Objectives: To antagonize the deleterious effects of the HIV-1 toxin extracellular Tat on uninfected immune cells, we developed a new strategy of anti-HIV-1 vaccine using an inactivated but immunogenic Tat (Tat toxoid). Tat toxoid has been assayed for safety and immunogenicity in seropositive patients.

Method: The phase I vaccine clinical trial testing Tat toxoid preparation in Seppic Isa 51 oil adjuvant was performed on 14 HIV-1-infected asymptomatic although biologically immunocompromised individuals (500-200 CD4+ cells/mm3).

Results: Following as many as 8 injections, no clinical defects were observed. All patients exhibited an antibody (Ab) response to Tat, and some had cell-mediated immunity (CMI) as evaluated by skin test in vivo and T-cell proliferation in vitro.

Conclusion: These results provide initial evidence of safety and potency of Tat toxoid vaccination in HIV-1-infected individuals.

Objectives: The major genotypes of the human polyomavirus JC (JCV) include type 1 (European), type 2 (Asian), type 3 (African), and type 4 (United States). Here we report characterization of the complete genome of a genotype obtained from the brain of an African American with systemic lupus erythematosus (SLE) and progressive multifocal leukoencephalopathy (PML).

Study design/methods: DNA extracted from JCV-infected brain tissue was subjected to whole-genome polymerase chain reaction (PCR) amplification and direct cycle sequencing. Relations to other JCV genotypes and the predicted amino acid sequence were analyzed.

Results: This African-American type 6 strain (#601) differs from strains of all other genotypes in about 2% of its DNA sequence. The length of the total coding region of strain #601 is increased to 4855 bp by the insertion of a single nucleotide in the large T-antigen intron. This strain, originally placed with the type 2 group on the basis of its sequence in the VT-intergenic region, is very closely related to strains recently identified in the urine of individuals from Ghana, West Africa.

Conclusions: This is the first example of an African JCV genotype identified in the brain of an African-American PML patient. The extent of sequence divergence of JCV type 6 suggests a split of type 6 strains before the separation of types 2 and 3. These findings confirm that distinctive African genotypes of JCV have been maintained in the African-American population and that they are capable of causing PML.

Objectives: It has been shown that > 90% of mothers of HTLV-I-infected children were themselves carriers of HTLV-I. This study was designed to determine the HTLV-I serostatus of mothers of patients with adult T-cell leukemia (ATL) and HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP), and to assess the association of age of exposure and disease outcome.

Study design/methods: In a cross-sectional study of the HTLV-I serostatus of mothers of HTLV-I-seropositive patients with ATL and HAM/TSP, 36 living mothers of patients with ATL and 15 mothers of patients with TSP/HAM were traced and enrolled.

Results: Five of the 15 (33%) mothers of patients with HAM/TSP and 35 of the 36 (97.2%) mothers of patients with ATL were HTLV-I-seropositive. All patients were breast-fed and none received blood transfusions.

Conclusion: This study confirms that infection with HTLV-I in early childhood can lead to ATL in later life, and that HAM/TSP can also result from early infection but more commonly results from infection acquired in adulthood. There are several reports of posttransfusion HAM/TSP, but ATL has not been reported following blood transfusion except in patients who were immunocompromised. Because the newborn infant is considered to be immunoincompetent, it seems that this is a necessary factor for the development of ATL after infection.

Objectives: To investigate which immune parameters, such as antibodies against HIV-1 specificities, or viral parameters, such as p24 antigenemia, are predictive of disease progression.

Study design: We performed studies on serum collected from individuals exhibiting two extremes of disease evolution--67 fast progressors (FP) and 182 nonprogressors (NP)--at their enrollment. After a 1- to 2-year clinical follow-up of 104 nonprogressors after their enrollment, we could determine the best serologic predictors for disease progression.

Methods: We investigated levels of antibodies to tetanus toxoid and to HIV antigens including Env, Gag, Nef, and Tat proteins, as well as p24 antigenemia, viremia, CD4 cell count, and interferon-alpha (IFN-alpha) titers in FPs and NPs, and we correlated these data with clinical and biologic signs of progression.

Results: p24 Antigenemia, a marker of viral replication, and anti-Tat antibodies were highly and inversely correlated in both groups (P < .001). Furthermore, anti-p24 antibodies and low serum IFN-alpha levels were correlated to the NP versus the FP cohort. Finally, among NPs, only antibodies to Tat and not to the other HIV specificities (Env, Nef, Gag) were significantly predictive of clinical stability during their follow-up.

Conclusion: Antibodies toward HIV-1 Tat, which are inversely correlated to p24 antigenemia, appear as a critical marker for a lack of disease progression. This study strongly suggests that rising anti-Tat antibodies through active immunization may be beneficial in AIDS vaccine development to control viral replication.

Objective: We sought to identify and characterize mechanisms of interaction between Kaposi's sarcoma cells and circulating leukocytes leading to leukocyte migration into the lesion.

Study design/methods: By using static and dynamic adhesion models, we measured the ability of late-stage KSY1 cells to support adhesion and transmigration of peripheral blood lymphocytes (PBL).

Results: We showed that resting as well as TNF-alpha- or PMA-activated KSY1 cells supported adhesion and transmigration of PBL with a higher efficiency compared with normal endothelial cells. The LFA1/ICAM1 pathway was totally involved in PBL adhesion to resting or TNF-alpha-activated KSY1 cells and partially responsible for adhesion to PMA-activated KSY1 cells. No inhibition of adhesion was observed by blockage of the VLA4 pathway. Under flow conditions, PBL/KSY1 cell interaction was totally dependent on L-selectin.

Conclusion: Our data indicate that KS cells mimic an endothelium-like structure by regulating extravasation of lymphocytes into lesions.

Objective: The recently discovered connection of chemokines and their receptors to HIV pathogenesis, and the description of the 32-bp deletion in the CCR5 gene (delta 32 CCR5), led to heightened excitement and numerous reports regarding their role in HIV transmission and disease progression. The populations in most of these reports, except for one, consisted of homosexual men. Our objective was to investigate the significance of delta 32 CCR5 in hemophilia patients in Israel.

Study design/methods: We have determined by polymerase chain reaction (PCR) the prevalence of delta 32 CCR5 in 34 HIV-seropositive Israeli patients with hemophilia A and compared them with a control group of 42 HIV-seronegative hemophilia patients.

Results: Thirteen heterozygotes were identified among the 76 hemophilia patients tested (allelic frequency, 8.5%), 5 (14.7%) among the HIV-seropositive patients, and 8 (19%) among the noninfected.

Conclusions: No protective advantage to delta 32 CCR5 heterozygosity was seen as far as infection with HIV is concerned. However, a trend of a slower progression to AIDS in delta 32 CCR5 heterozygotes compared with wild-type homozygotes may be apparent, although no absolute correlation could be made.

Objectives: We wished to generate a number of genetic constructs containing mutations in the protease (PR) and reverse transcriptase (RT) genes of the Gag-Pol of human immunodeficiency virus type 1 (HIV-1) and to transfect these constructs into COS-7 cells to determine their effect on wild-type (wt) viral replication.

Results: The mutated Gag-Pol polyproteins were incorporated into viral particles. Gag-Pol proteins that were mutated in PR as well as combinations of mutations in PR and RT inhibited the production of fully processed and infectious viral particles when these constructs were coexpressed with the infectious HIV-1 molecular clone pBH10. Viral particles produced after cotransfection of COS-7 cells with both pBH10 and infectious constructs containing Gag-Pol, mutated in PR alone or in both RT and PR, showed abnormal processing and lower infectivity. Complementation experiments in which pBH10 mutated in PR was coexpressed with wt Gag-Pol showed that the latter could be incorporated into the viral particles that were generated. COS-7 cells stably transfected with Gag-Pol, mutated in PR or in both PR and RT, and subsequently transfected with pBH10, produced levels of p24 and RT activity that were substantially diminished in comparison with levels produced by cells transfected with wt pBH10 alone.

Conclusions: These results suggest that trans-dominant effects were potentially responsible for the observed inhibition of viral replication.

Objectives: Previous studies have shown that strains of human polyomavirus JC (JCV) of Asian origin (type 2) are much more highly represented in progressive multifocal leukoencephalopathy (PML) brain than would be expected from their frequency of excretion in urine samples of a comparable control group. The present studies were designed to test whether one subtype of type 2 was preferentially elevated.

Study design/methods: The statistical relation between JCV subtypes represented in PML brain tissue from 51 probands and those in urine samples from 115 control individuals was examined.

Results: The proportion of the JCV subtype 2B in PML brain (36%) was highly significantly increased relative to its occurrence in control urine samples (5.9%; P < .001). Type 1 and its subtypes were not different in the PML brain and control urine cohorts. The number of type 4 strains in PML brains was reduced, although the difference did not reach statistical significance (P = .08).

Conclusions: The results predict that the human immunodeficiency virus (HIV)-positive individuals at highest risk of PML infection are those carrying the JCV genotype known as type 2B. Prospective studies will be required to confirm this finding.