Loading...
(1/2101) Hepatitis C virus (HCV) specific immune responses in anti-HCV positive patients without hepatitis C viraemia.

BACKGROUND/AIMS: Most patients infected with hepatitis C virus (HCV) develop chronic infection and persistent viraemia. The immune mechanisms responsible for resolution of viraemia remain poorly understood. HCV specific humoral and cellular immune responses in patients with and without viraemia were investigated. METHODS: In vitro T helper (TH) lymphocyte responses to structural and non-structural HCV proteins were determined by means of proliferative response and cytokine production in 35 anti-HCV positive/HCV RNA negative patients and in 31 patients with chronic HCV infection and persistent viraemia. Humoral responses were determined by measuring HCV specific antibody quantity and specificity. RESULTS: A TH response to two or more HCV proteins was present in 18 of 35 patients with serological viral clearance compared with just one of 31 viraemic patients (p = 0.00001). HCV specific interferon-gamma production was increased only in the former group. In contrast, the antibody levels were significantly lower and directed at fewer HCV antigens in patients with undetectable HCV RNA. CONCLUSIONS: Patients without viraemia after HCV infection frequently have strong TH lymphocyte responses of the TH1 type to multiple HCV antigens many years after the onset of infection, whereas antibody responses are less marked. These results suggest that control of HCV replication may depend on effective TH lymphocyte activation.  (+info)

(2/2101) No evidence for an effect of the CCR5 delta32/+ and CCR2b 64I/+ mutations on human immunodeficiency virus (HIV)-1 disease progression among HIV-1-infected injecting drug users.

The relationship between CCR5 and CCR2b genotypes and human immunodeficiency virus (HIV)-1 disease progression was studied among the 108 seroconverters of the Amsterdam cohort of injecting drug users (IDUs). In contrast to earlier studies among homosexual men, no effect on disease progression of the CCR5 Delta32/+ and the CCR2b 64I/+ genotypes was found, when progression to AIDS, death, or a CD4 cell count <200/microL was compared by a Cox proportional hazards model. Furthermore, CD4 cell decline (by a regression model for repeated measurements) and virus load in the first 3 years after seroconversion did not differ between the CCR5 and CCR2b wild type and heterozygous genotypes. A nested matched case-control study also revealed no significant effect of the CCR5 and CCR2b mutations. Immunologic differences between IDUs and homosexual men may account for the observed lack of effect. Alternatively, difference in transmission route or characteristics of the HIV-1 variants that circulate in IDUs could also explain this phenomenon.  (+info)

(3/2101) Persistently high Epstein-Barr virus (EBV) loads in peripheral blood lymphocytes from patients with chronic active EBV infection.

Chronic active Epstein-Barr virus infection (CAEBV) is a severe illness with unusual EBV activation that persists for years, and its pathogenesis is largely unknown. After the creation of an accurate and reproducible polymerase chain reaction system to quantify EBV DNA, virus loads in peripheral blood lymphocytes (PBL) were determined in 54 children: 15 with CAEBV, 16 with infectious mononucleosis (IM), and 23 healthy children. Children with CAEBV and those with IM had high virus loads. Lower loads were detected in 47% of seropositive healthy donors. There were two distinct differences between children with CAEBV and those with IM: The former had greater viral replication (10(3)-10(7) copies/2.5x10(5) PBL) than those with IM, and viral replication declined in children with IM whereas active replication persisted for years in subjects with CAEBV. Persisting high virus loads are a possible diagnostic criterion for CAEBV. EBV loads may enable classification and prognosis of EBV infections.  (+info)

(4/2101) High prevalence of hepatitis G virus (HGV) infections in dialysis staff.

BACKGROUND: Patients on renal replacement therapy, haemodialysis (HD), or after kidney transplantation (TX), are known to be at risk of acquiring blood-borne infections (HBV, HCV). GBV-C/Hepatitis G virus (HGV) has been described recently and is considered to cause blood-borne infections. The aim of this study was to analyse the risk for the medical staff of HD and TX patients to acquire HGV infection. METHODS: Eighty-five HD patients and 86 TX recipients were compared with 49 health-care workers and 64 blood donors as controls. The HGV prevalence was determined by RT-PCR and antibodies to E2 protein. RESULTS: A high prevalence of HGV was found in the medical staff (24%) which nearly corresponded to the prevalence of the patients (TX 36%, HD 25%) but not to the controls (9%). In contrast, the prevalence of HCV was low in the medical staff (2%) and controls (0%) but high in HD (13%) and TX (13%). Age and duration of employment in the department did not significantly influence the HGV prevalence in staff. The number of viraemic subjects in staff was high, possibly indicating a more recent infection. CONCLUSION: An occupational risk for HGV exists in medical staff of dialysis and transplant patients. Further routes of transmission than only parenteral may play a role in this setting.  (+info)

(5/2101) Activation in vivo of retroperitoneal fibromatosis-associated herpesvirus, a simian homologue of human herpesvirus-8.

Retroperitoneal fibromatosis-associated herpesvirus of rhesus macaques (RFHVMm) is a gammaherpesvirus closely related to human herpesvirus-8 (HHV-8), which is thought to be a necessary cofactor for the development of Kaposi's sarcoma (KS) in humans. Here, RFHVMm infection of rhesus macaques exposed to the D-type retrovirus simian retrovirus-2 (SRV-2) is described. Development of SRV-2 viraemia, infection with simian immunodeficiency virus or administration of cyclosporin A could result in persistent RFHVMm viraemia. From this, it is concluded that productive retrovirus infection or otherwise-induced immune suppression has the ability to activate this herpesvirus in vivo. Elevated levels of circulating interleukin-6, a cytokine that plays a central role in KS, were found in RFHVMm-viraemic animals. In viraemic animals, RFHVMm was found in tissues that are common sites for the development of AIDS-associated KS, especially the oral cavity. Together, these data suggest a common biology between RFHVMm infection of macaques and HHV-8 infection and pathogenesis in humans.  (+info)

(6/2101) Clinical significance of expression of human cytomegalovirus pp67 late transcript in heart, lung, and bone marrow transplant recipients as determined by nucleic acid sequence-based amplification.

Human cytomegalovirus (HCMV) infection was monitored retrospectively by qualitative determination of pp67 mRNA (a late viral transcript) by nucleic acid sequence-based amplification (NASBA) in a series of 50 transplant recipients, including 26 solid-organ (11 heart and 15 lung) transplant recipients (SOTRs) and 24 bone marrow transplant recipients (BMTRs). NASBA results were compared with those obtained by prospective quantitation of HCMV viremia and antigenemia and retrospective quantitation of DNA in leukocytes (leukoDNAemia). On the whole, 29 patients were NASBA positive, whereas 10 were NASBA negative, and the blood of 11 patients remained HCMV negative. NASBA detected HCMV infection before quantitation of viremia did but after quantitation of leukoDNAemia and antigenemia did. In NASBA-positive blood samples, median levels of viremia, antigenemia, and leukoDNAemia were significantly higher than the relevant levels detected in NASBA-negative HCMV-positive blood samples. By using the quantitation of leukoDNAemia as the "gold standard," the analytical sensitivity (47.3%), as well as the negative predictive value (68. 3%), of NASBA for the diagnosis of HCMV infection intermediate between that of antigenemia quantitation (analytical sensitivity, 72. 3%) and that of viremia quantitation (analytical sensitivity, 28.7%), while the specificity and the positive predictive value were high (90 to 100%). However, with respect to the clinically relevant antigenemia cutoff of >/=100 used in this study for the initiation of preemptive therapy in SOTRs with reactivated HCMV infection, the clinical sensitivity of NASBA reached 100%, with a specificity of 68. 9%. Upon the initiation of antigenemia quantitation-guided treatment, the actual median antigenemia level was 158 (range, 124 to 580) in SOTRs who had reactivated infection and who presented with NASBA positivity 3.5 +/- 2.6 days in advance and 13.5 (range, 1 to 270) in the group that included BMTRs and SOTRs who had primary infection (in whom treatment was initiated upon the first confirmation of detection of HCMV in blood) and who presented with NASBA positivity 2.0 +/- 5.1 days later. Following antiviral treatment, the durations of the presence of antigenemia and pp67 mRNA in blood were found to be similar. In conclusion, monitoring of the expression of HCMV pp67 mRNA appears to be a promising, well-standardized tool for determination of the need for the initiation and termination of preemptive therapy. Its overall clinical impact should be analyzed in future prospective studies.  (+info)

(7/2101) Multicenter comparison of the digene hybrid capture CMV DNA assay (version 2.0), the pp65 antigenemia assay, and cell culture for detection of cytomegalovirus viremia.

We compared the Digene Hybrid Capture CMV DNA Assay version 2.0, the pp65 antigenemia assay, traditional tube culture, and shell vial culture for the detection of cytomegalovirus (CMV) viremia in several patient populations at three centers. Of 561 blood specimens collected from 402 patients, complete clinical and laboratory data were available for 489. Using consensus definitions for true positives and true negatives, the sensitivities of the Hybrid Capture assay, antigenemia, shell vial, and tube culture were 95, 94, 43, and 46%, respectively. The specificities of the Hybrid Capture assay and antigenemia were 95 and 94%, respectively. At all three study sites, the detected level of CMV viremia was significantly higher with the Hybrid Capture assay or antigenemia than with shell vial and tube culture. In a group of 131 healthy nonimmunosuppressed volunteers, the Hybrid Capture assay demonstrated a specificity of over 99%. The Hybrid Capture assay is a standardized assay that is simple to perform and can utilize whole blood specimens that have been stored for up to 48 h. The high sensitivity and specificity of the Hybrid Capture assay along with its simplicity and flexibility make it a clinically useful assay for the detection of CMV viremia in immunocompromised or immunosuppressed patients. Further evaluation to determine its role in predicting CMV disease and for monitoring the therapeutic response to anti-CMV therapy is needed.  (+info)

(8/2101) Dramatic rise in plasma viremia after CD8(+) T cell depletion in simian immunodeficiency virus-infected macaques.

To determine the role of CD8(+) T cells in controlling simian immunodeficiency virus (SIV) replication in vivo, we examined the effect of depleting this cell population using an anti-CD8 monoclonal antibody, OKT8F. There was on average a 99.9% reduction of CD8 cells in peripheral blood in six infected Macaca mulatta treated with OKT8F. The apparent CD8 depletion started 1 h after antibody administration, and low CD8 levels were maintained until day 8. An increase in plasma viremia of one to three orders of magnitude was observed in five of the six macaques. The injection of a control antibody to an infected macaque did not induce a sustained viral load increase, nor did it significantly reduce the number of CD8(+) T cells. These results demonstrate that CD8 cells play a crucial role in suppressing SIV replication in vivo.  (+info)