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PubMed2004

Genotype prevalence, viral load and outcome of hepatitis B virus precore mutant infection in stable patients and in patients after liver transplantation.

OBJECTIVE: The precore mutant is detectable in most Israeli patients with persistent hepatitis B virus (HBV) infection. The aim of this study was to determine the prevalence of HBV genotypes, viral load and outcome of precore mutant infection in stable patients and in patients after liver transplantation. METHODS: The prevalence of HBV genotype and viral load were investigated in 81 patients with HBV precore mutant infection. Of these, 50 patients (40 males, 10 females; mean age 43.4 +/- 11.0 yr) underwent liver transplantation and were serum HBV DNA-negative by hybridization at the time of transplantation. Patients received long-term HBV immunoprophylaxis and immunosuppression, and lamivudine in cases of graft HBV recurrence. The remaining 31 patients were stable, with serum anti-HBe-positivity. Genotypes were tested by restriction fragment length polymorphism of an S gene amplicon. Precore mutations were studied with an INNO-LiPA probe assay. RESULTS: Follow-up was 46.6 +/- 37.7 months. Most of the transplanted group was of Middle Eastern origin (53.6%); the remainder were from Eastern Europe (21.4%), Western Europe and the USA (10.8%), Africa (7.1%), and Asia (7.1%). In the transplanted group, the pre-transplant HBV genotype D was the most prevalent (96%), while genotype A was found in only 4%. Eleven patients (22%) developed recurrent HBV infection post-transplantation. There were no differences in genotype distribution between patients with graft reinfection or lamivudine resistance and patients without recurrence. Mean viral load at recurrence was 148.4 x 10(6) +/- 60.4 x 10(6) copies/mL. The stable group had a similar origin and HBV genotype prevalence, but a lower mean viral load of 12.4 x 10(6) +/- 29.4 x 10(6) copies/mL (p = 0.007). The prevalence of mutations at the precore region and codon 28 was similar in both groups. CONCLUSIONS: The chronic precore mutant HBV-infected patients were characterized as follows: (i) genotype D was the most frequent genotype, (ii) the HBV genotype distribution was similar in patients with stable infection and after liver transplantation, (iii) viral load at recurrence was significantly higher than in stable infection, and (iv) HBV genotype was unrelated to the development of recurrence or lamivudine resistance in the tested population.

Adult↗

PubMed2001

Viral load in breast milk correlates with transmission of human cytomegalovirus to preterm neonates, but lactoferrin concentrations do not.

In vitro, lactoferrin (LF) strongly inhibits human cytomegalovirus (HCMV), which led us to hypothesize that in vivo HCMV might also be inhibited in secretions with high LF concentrations. In breast milk, high viral loads observed as high viral DNA titers tended to coincide with higher LF levels. However, the LF levels did not correlate to virus transmission to preterm infants. The viral load in the transmitting group was highest compared to the nontransmitting group. We conclude that viral load in breast milk is an important factor for transmission of the virus.

Breast Feeding↗

PubMed2000

Application of viral-load kinetics to identify patients who develop cytomegalovirus disease after transplantation.

BACKGROUND: Cytomegalovirus (CMV) continues to be a major problem post-transplantation; early markers for predicting patients at risk of CMV disease are needed. Peak CMV load in the blood correlates with CMV disease but frequently occurs too late to provide prognostic information. METHODS: 359 transplant recipients (162 liver, 87 renal, and 110 bone marrow) were prospectively monitored for CMV DNA in the blood with qualitative and quantitative PCR. 3873 samples were analysed. The CMV load in the first PCR-positive sample and the rate of increase in CMV load in blood during the initial phase of replication were assessed as risk factors for CMV disease using logistic regression. FINDINGS: 127 of the 359 patients had CMV DNA in the blood and 49 developed CMV disease. Initial viral load correlated significantly with peak CMV load (R2=0.47, p=<0.001) and with CMV disease (odds ratio 1.82 [95% CI 1.11-2.98; p=0.02; 1.34 [1.07-1.68], p=0.01, and 1.52 [1.13-2.05], p=0.006, per 0.25 log10 increase in viral load for liver, renal, and bone-marrow patients, respectively). The rate of increase in CMV load between the last PCR-negative and first PCR-positive sample was significantly faster in patients with CMV disease (0.33 log10 versus 0.19 log10 genomes/mL daily, p<0.001). In multivariate-regression analyses, both initial CMV load and rate of viral load increase were independent risk factors for CMV disease (1.28 [1.06-1.52], p=0.01, per 0.25 log10 increase in CMV load and 1.52 [1.06-2.17], p=0.02, per 0.1 log10 increase in CMV load/mL daily, respectively). INTERPRETATION: CMV load in the initial phase of active infection and the rate of increase in viral load both correlate with CMV disease in transplant recipients; in combination, they have the potential to identify patients at imminent risk of CMV disease.

Cytomegalovirus↗

PubMed2002

Plasma RNA viral load in human immunodeficiency virus type 2 subtype A and subtype B infections.

Human immunodeficiency virus type 2 (HIV-2) is much less pathogenic than HIV-1, and HIV-2 infection is associated with plasma viral loads significantly lower than those found in HIV-1 infection. We have developed a real-time quantitative PCR method for measuring the HIV-2 RNA load that covers the range of genetic diversity of HIV-2 isolates and that detects extremely low viral loads. Samples from 49 patients were studied. Proviral DNA was first detected and quantified. The strains that were detected were then genotyped: 21 patients were infected with HIV-2 subtype A and 15 patients were infected with HIV-2 subtype B; 1 patient was infected with a highly divergent strain. Env PCR failed for the remaining 12 patients, so subtypes could not be determined. For viral RNA quantification, a stock of HIV-2 strain NIHZ, which was counted by electron microscopy, was used as the standard. Several primer sets targeting the highly conserved gag region were evaluated. Various primer combinations failed to amplify subtype B strains. With the final primer pair selected, which detected both subtype A and subtype B strains, the sensitivity of the assay was 100% at a viral load of 250 copies/ml and 66% at a viral load of 125 copies/ml. We found a correlation between the CD4(+)-cell count, the clinical stage, and the plasma HIV-2 RNA level. The median plasma HIV-2 RNA value for the 33 asymptomatic patients was 2.14 log(10), whereas it was 3.1 log(10) for the 16 patients with AIDS (P < 0.01). Proviral DNA was detectable in 18 symptom-free patients with high CD4(+)-cell counts, in whom viral RNA was undetectable.

Base Sequence↗

PubMed2005

The efficiency of sperm washing in removing human immunodeficiency virus type 1 varies according to the seminal viral load.

We evaluated the relationship between the seminal HIV-1 viral load and the efficiency of a standardized sperm-washing procedure in removing HIV-1 RNA from semen samples. The results obtained indicate that the amount of virus present in the original sample affects the efficiency of the procedure and suggest that the seminal viral load should be preevaluated before enrolling an HIV-serodiscordant couple in an assisted reproduction protocol.

Fertilization in Vitro↗

PubMed2006

Prevalence of oral lesions in HIV patients related to CD4 cell count and viral load in a Venezuelan population.

AIM: To determine the prevalence of oral lesions in a HIV+ group of patients, related to CD4 cell count and viral load in a Venezuelan population. MATERIALS AND METHODS: In the present study, we evaluated 75 HIV+ adult patients, attended at the Center of Infectious Diseases, at the Faculty of Dentistry, Central University of Venezuela. Each patient was clinically examined for detection of oral mucosal lesions. In addition, CD4 cell count was determined by flow cytometry, as well as viral load by RT-PCR (Amplicor HIV-RNA, TM test 1.5, Roche). RESULTS: 85% (64/75) of HIV/AIDS patients showed associated HIV lesions. Oral Candidiasis constituted the most common lesion representing a 61% (39/64), followed by Oral Hairy Leukoplakia 53% (34/64); Oral Leukoplakia 34% (22/64), Melanic Hyperpigmentation 38% (18/64); Papilloma 13 (6/64), Lineal Gingival Erythema 8% (5/64); Aphtous Recurrent Stomatitis 5% (4/64) and Kaposi's Sarcoma 5% (3/64). Only one case of the following lesions were represented by Non Hodgkin Lymphoma, Multifocal Epithelial Hyperplasia, Recurrent Herpes, Histoplasmosis and Molluscum Contagiosum. The patients with a viral load of 30.000 copies/mm3 exhibited oral lesions related with HIV, independent of CD4 cell count, although patients with CD4+ levels of 200 cel/mm3 were more susceptible to develop these lesions. CONCLUSIONS: The most common oral lesion was Oral Candidiasis followed by Oral Hairy Leukoplakia, Oral Leukoplakia and Melanic Hyperpigmentation. A high viral load was strongly associated to the oral lesions occurrence independently of CD4+ cell count.

Adult↗

PubMedDate not supplied

Initial daily interferon administration can gain more eradication of HCV-RNA in patients with chronic hepatitis C, especially with serum intermediate viral load.

BACKGROUND/AIMS: We studied the effect of initial daily administration of interferon for the treatment of chronic hepatitis C, especially in patients with intermediate viral load. METHODOLOGY: Consecutive patients who met the inclusion criteria were randomly enrolled into two groups in this study. All patients analyzed could be treated with interferon-alpha for 6 months. Patients in group A were administered 6 million units of interferon-alpha subcutaneously daily initially for 2 weeks and then thrice weekly. Patients in group B were treated with the same dose of interferon-alpha thrice weekly from the first administration. We decided the criteria of complete remission as the absence of serum HCV-RNA at both points of the end of interferon treatment and 6 months later. RESULTS: Due to the relationship between the efficacy and serum viral load, we decided the criteria of the intermediate load as the quantitative value of serum HCV-RNA to be not lower than 10(5.0) and not higher than 10(6.5) copies/ml. Seventy-six and 78 patients, whose genotype and quantitative value of serum HCV-RNA could be measured before treatment, were analyzed in group A and B, respectively. The rate of complete remission in group A (40.8%) was higher than that in group B (25.6%), significantly (p = 0.046). In the intermediate viral load group, the rate of complete remission in group A (52.3%) was significantly higher than that in group B (29.3%) (p = 0.045). In the patients with genotype 1 b virus, the rate of complete remission had a tendency to be higher in group A (33.3%) than in group B (17.4%) (not significant). In the patients with genotype 2, the rate of complete remission was higher in group A (77.8%) than in group B (41.2%) (significant, p = 0.041). CONCLUSIONS: These results suggest that the initial daily interferon administration is necessary to gain a higher rate of serum HCV-RNA eradication in patients with intermediate viral load in chronic hepatitis C.

Adult↗

PubMed1998

Role of HIV-1 phenotype in viral pathogenesis and its relation to viral load and CD4+ T-cell count.

The predictive value of HIV-1 phenotype in peripheral blood mononuclear cell (PBMC) coculture and the relation among viral phenotype, viral load, and CD4+ T-cell count were examined in two studies. In study A, 132 HIV-1-infected individuals were examined retrospectively for the relation between the result of their initial HIV cultivation in PBMC coculture and survival rate 6 years later. In study B, 176 patients were examined since 1994 for markers of HIV disease progression. HIV-1 phenotype was determined by PBMC cocultivation, viral load by NASBA HIV RNA QT System, and CD4+ T-cell count by flow cytometry. In study A, the percentage of survival for patients with initial negative virus culture was significantly higher (95%) than in patients with nonsyncytia-inducing (NSI) isolates (78%) and syncytia-inducing (SI) isolates (21%) (P < 0.05 and P< 0.0001, respectively). When SI phenotype was subdivided into moderately cytopathogenic and highly cytopathogenic, significant differences in the rate of survival between these subgroups could be observed (45% vs. 14%; P < 0.05). In study B, progression from negative virus culture to the isolation of NSI variants was associated with increasing viral load (P < 0.0001) but did not affect CD4+ T-cell count significantly (P> 0.07), whereas the switch from NSI to SI virus was accompanied by significant decline of CD4+ T-cells (P < 0.0001) but no change in viral load (P > 0.21). Thus, isolation and phenotyping of HIV represents an additional striking predictive marker for progression of HIV infection.

CD4 Lymphocyte Count↗

PubMed2002

Amino acid substitutions in the nonstructural region 5A of hepatitis C virus genotypes 2a and 2b and its relation to viral load and response to interferon.

OBJECTIVES: The interferon sensitivity-determining region (ISDR) in nonstructural region 5A (NS5A) of hepatitis C virus genotype 1b has been reported to correlate with response to interferon therapy and viral load. Recently the correlation between NS5A and response to interferon in genotype 2a was also reported. We examined the region of genotypes 2a and 2b corresponding to the ISDR of genotype lb to elucidate its correlation with response to interferon and viral load. METHODS: The sequences of amino acid positions 2213-2248 in NS5A were determined in 39 patients with genotype 2a and 12 patients with genotype 2b. RESULTS: In the patients infected with genotype 2a, the number of amino acid substitutions in the ISDR-corresponding region compared with the consensus sequence of genotype 2a was significantly correlated with viral load (p = -0.541, p < 0.001) and with response to interferon therapy (p < 0.05); 83% of the patients with three or more substitutions obtained sustained responses, whereas only 44% of those with less than three substitutions obtained sustained responses. Multivariate analysis confirmed that the number of substitutions in the ISDR-corresponding region of genotype 2a was one of the independent predictors of response to interferon therapy (discriminant coefficient = 1.35, p < 0.001). CONCLUSIONS: Substitutions in the ISDR-corresponding region in NS5A of hepatitis C virus genotype 2a was confirmed to correlate to viral load and response to interferon therapy. In genotype 2b, further work must be considered because of the small number of patients studied.

5' Flanking Region↗

PubMed2005

Early viral kinetics and treatment outcome in combination of high-dose interferon induction vs. pegylated interferon plus ribavirin for naive patients infected with hepatitis C virus of genotype 1b and high viral load.

An investigation was carried out to determine whether early viral monitoring could predict efficiently the virological response to combination therapy of two different regimens in treatment-naive chronic hepatitis C patients infected with genotype 1b with high baseline viral load. Patients were randomly assigned to receive interferon (IFN) alpha-2b induction (6 MU daily for 2 weeks) followed by 6 MU thrice weekly for 46 weeks (IFN/R group; n = 20), or pegylated IFN alpha-2b (1.5 microg/kg) weekly for 48 weeks (PEG/R group; n = 28), in combination with ribavirin (600-1,000 mg daily). Serum HCV RNA was quantitated at 0, 6, 12, 24, and 48 hr post-dose, weekly during the first 4 weeks, and thereafter viral kinetics were assessed every 4 weeks. The sustained virological response rates in the IFN/R and PEG/R groups were 40% (8/20) and 43% (12/28), respectively. The non-virological response rates were 40% (8/20) and 39% (11/28), respectively. The cumulative virological response rates were similar in both groups. Multivariate analyses identified no independent baseline variables linked to sustained virological or non-virological response. Early log viral load changes from baseline in both groups were significantly greater at all time-points after 24 hr in virological response patients than in non-virological response patients (P < 0.001 for all). On the receiver operating characteristics curves for prediction of non-virological response, the area under the curves (0.951-1.000), sensitivity (90%-100%), and negative predictive value (96%- 100%) were similar at any time-points after 24 hr. For prediction of sustained virological response, sensitivity of 80% with 86% negative predictive value was observed for negative HCV RNA at week 12, with the highest area under the curves value of 0.919. The results suggest that early monitoring of viral kinetics is a useful measure to predict virological response, and might facilitate development of rational and effective therapeutic strategies.

Adult↗

PubMed1999

Effect of changing antiretroviral therapy on human immunodeficiency virus viral load: experience with fifty-four perinatally infected children.

BACKGROUND: Experience in adults has shown that combination therapy including HIV protease inhibitors (PI) can profoundly affect viral replication and slow progression of HIV-associated disease. Trials defining the influence of PI and combination therapies on long term outcome of HIV infection in children have not yet been completed. Experience with infants and children who were receiving routine care in an HIV specialty clinic was reviewed to characterize the effect of changes involving one, two or three antiretrovirals. METHODS: Clinical and laboratory findings of children in whom antiretroviral therapy was changed were retrospectively reviewed. Successful response was defined as a reduction of viral load of at least 0.7 log10 RNA copies/ml lasting for at least 3 months. Differences in characteristics and the character of the response associated with successful and unsuccessful changes were analyzed. RESULTS: Of the 72 changes in therapy that were made in 54 children, 29 resulted in a successful response. A change involving 3 antiretrovirals was more likely to produce a successful response than a change involving 1 agent (6 of 9 vs. 6 of 24; P < 0.04). Reduction of viral load by > 100-fold or to undetectable amounts occurred more frequently in children who responded to a regimen containing a PI than in children who responded to reverse transcriptase inhibitors (11 of 21 vs. 1 of 8; P=0.05). Furthermore successful responses associated with addition of a PI were associated with a greater reduction in viral load than those that involved reverse transcriptase inhibitors (1.63+/-0.60 vs. 0.99+/-0.12 log10; P=0.003). CONCLUSIONS: This experience suggests that changing antiretroviral therapy in HIV-infected children to regimens containing three drugs is more likely to result in a successful virologic outcome than changes in therapy involving one drug. This experience further supports the conclusion that including a PI as part of an antiretroviral regimen is more likely to result in a greater reduction in viral load in children.

Anti-HIV Agents↗

PubMedDate not supplied

Use of cytokine polymorphisms and Epstein-Barr virus viral load to predict development of post-transplant lymphoproliferative disorder in paediatric liver transplant recipients.

OBJECTIVE: Currently there are no tests to accurately identify paediatric liver transplant patients at risk for post-transplant lymphoproliferative disorder (PTLD). Herein we describe the use of cytokine polymorphisms and real-time quantitative polymerase chain reaction (qPCR) Epstein-Barr virus (EBV) viral load to identify patients at risk for PTLD development. METHODS: Between 2001 and 2004, approximately 1047 patient samples were collected for qPCR for EBV in 59 patients. EBV viral load was reported in three groups: low EBV (<4,000 copies/microg DNA), high EBV/no PTLD (>4000 copies/microg DNA) and biopsy-proven PTLD. All 59 patients also had cytokine polymorphism genotyping performed for six cytokine polymorphisms (transforming growth factor (TGF)-beta, tumor necrosis factor (TNF)-alpha, interleukins (IL)-6, IL-10, IL-2, and interferon (IFN)-gamma) from DNA isolated from peripheral blood mononuclear cells. Positive predictive value (PPV) and negative predictive value (NPV) were calculated using qPCR and cytokine polymorphism results. Data are reported as a mean +/- standard error of the mean. RESULTS: There were 35 males and 24 females with a mean follow-up of 34.9 months. EBV viral load had a PPV and NPV of 29 and 95%, respectively. The low IFN-gamma (A/A) polymorphism was found to be present in 4/6 PTLD patients (67%) and only 17/53 (33%) non-PTLD patients. When the low A/A IFN-gamma polymorphism was combined with EBV viral load for prediction of PTLD, PPV and NPV were 57 and 93%, respectively. DISCUSSION: Use of cytokine genotyping in conjunction with qPCR for EBV viral load can significantly improve the predictive value of diagnostic tests for identification of patients at high risk for PTLD.

Adolescent↗

PubMed2006

[Effects of traditional Chinese medicine on CD4 + T cell counts and HIV viral loads during structured treatment interruption in highly active antiretroviral therapy].

OBJECTIVE: To explore the impacts of traditional Chinese medicine (TCM) on CD4 + T cell counts and human immunodeficiency virus (HIV) viral loads during the course of structured treatment interruption (STI) in highly active antiretroviral therapy (HAART). METHODS: Nineteen HIV/ADIS patients were treated for 14 months as follows: initiated with zidovudine/lamivudine + efavirdine for 6 months, then discontinued the therapy and treated with TCM instead for 2 months. HAART was then reinitiated for another 3 months, and then discontinued and replaced with TCM for another 3 months. The changes of CD4 + T cell counts and HIV viral loads were measured. RESULTS: During the first STI of HAART, 43.8% of patients had no viral rebounds one month later, and 62.6% had stable or increased immune functions; 18.8% had no viral rebounds two months later, and 43.8% had stable or increased immune functions. Changes of viral loads were not significantly different between these two months (P = 0.097), while CD4 + T cell counts significantly decreased two months later compared with one month later (P = 0.043). During the second STI of HAART, 33.3% of patients had no viral rebounds one month later, and 64.3% had stable or increased immune functions; 13.3% had no viral rebounds 3 months later and 46.6% had stable or increased immune functions. Changes of viral loads had significant difference (P = 0. 017), while CD4 + T cell counts at month 12 elevated significantly compared with the baseline (P = 0.014). CONCLUSIONS: TCM can suppress the viral rebounds during STI-HAART, maintain immune functions. However, this effect may decrease along with the prolongation of STI-HAART.

Adult↗

PubMed2002

Epstein-Barr viral load as a tool to diagnose and monitor post-transplant lymphoproliferative disease.

Epstein-Barr virus (EBV)-induced post-transplant lymphoproliferative disease (PTLD) continues to be a rare but severe complication following transplantation. EBV viral load is used as a tool to identify patients at risk for developing PTLD. However, studies on EBV viral load are hard to compare since study design as well as EBV detection method and calculation of results are highly variable. In the majority of cases EBV viral load is increased in patients with PTLD compared to patients without disease. There is, however, some overlap. Some individual patients with only low viral load show PTLD while others show the opposite. The major future goals will be to standardize EBV-DNA detection in order to generate comparable data in different centers and to establish cut-off values to distinguish patients with PTLD from patients without with a high precision.

DNA, Viral↗

PubMed2004

Short-term risk of AIDS according to current CD4 cell count and viral load in antiretroviral drug-naive individuals and those treated in the monotherapy era.

BACKGROUND: One key piece of information required when deciding whether to initiate antiretroviral therapy is the risk of AIDS before the next clinic visit. Information on the short-term (6-month) risk of AIDS according to the current viral load and CD4 cell count in untreated individuals and those treated in the zidovudine monotherapy era (i.e., pre-September 1995), especially in those with CD4 cell count > 200 x 10 cells/l, is lacking. METHODS: Risk of AIDS was assessed in 3226 subjects with viral load and CD4 cell count known before initiation of antiretroviral therapy or during the zidovudine monotherapy era. These were from CASCADE Collaboration in which data from 20 cohorts of individuals with known dates of seroconversion to HIV, based in clinics in Europe and Australia, have been combined. RESULTS: During a total 5126.0 person-years of follow-up, 219 individuals developed AIDS. In those with current CD4 cell count < 200 x 10 cells/l, 6-month risks were 4.9, 12.7, 17.7 and 22.4% for viral load groups < 10 000, 10 000-29 999, 30 000- 99 999 and > or = 100 000 copies/ml, respectively. For CD4 cell counts 200-349 x 10 cells/l risks were 0.5, 1.6, 3.2 and 4.7%, respectively, for the four viral load groups while the corresponding values for group with CD4 cell count > or = 350 x 10 cells/l were 0.2%, 0.5%, 0.9% and 2.2%, respectively. Results were similar when analysis was restricted to those with no antiretroviral drug experience. Older people had a higher risk of AIDS for a given CD4 cell count and viral load than younger people. CONCLUSION: Combined with consideration of other issues, these estimates should prove useful information when deciding whether to initiate antiretroviral therapy in HIV-infected individuals.

Acquired Immunodeficiency Syndrome↗

PubMed2003

Noninvasive detection of new simian immunodeficiency virus lineages in captive sooty mangabeys: ability to amplify virion RNA from fecal samples correlates with viral load in plasma.

The sooty mangabey (SM) (Cercocebus atys) is the natural host of a simian immunodeficiency virus, termed SIVsm, which gave rise to human immunodeficiency virus type 2. Data on the geographic distribution, prevalence, and genetic diversity of SIVsm in the wild remains limited. To address this issue, noninvasive strategies based on screening SM fecal and urine specimens for SIVsm-specific antibodies and virion RNA (vRNA) were developed, and the results were correlated with viral loads in plasma. Twenty-three SIVsm-infected and 27 uninfected SMs were evaluated. Time-matched urine, fecal and plasma samples were collected over a 2-month period from 16 captive naturally infected SMs. The remaining 7 infected and 27 uninfected SMs were sampled once. Each specimen was subjected to enhanced chemiluminescence-Western blot analysis and nested reverse transcriptase (RT) PCR. The results showed that urine was highly sensitive (96%) and specific (100%) for detection of SIVsm antibodies, while fecal detection was much less sensitive (16%). Conversely, vRNA detection was more sensitive in feces (50%) than in urine (2%) samples. Fecal-vRNA detection correlated with viral loads in plasma (P < 0.002). SMs with detectable fecal vRNA had a mean viral load in plasma of 458,006 copies/ml, while those with undetectable fecal vRNA had a mean viral load in plasma of 29,428 copies/ml. Moreover, for every log increase in the viral load in plasma, the odds of detecting virus in fecal samples increased 87-fold. Genetic diversity of SIVsm in the SM colony was characterized by sequencing partial gag (846 bp) and gp43 (439 bp) fragments. Surprisingly, four new SIVsm lineages were identified, two of which were initially detected by fecal RT-PCR. This study documents the suitability of noninvasive methods for the detection and molecular characterization of new SIV variants. These assays will be useful for studying the phylogeny and epidemiology of SIVsm infections in the wild, and they hold promise as tools for investigating natural SIV infections in endangered nonhuman primates.

Animals↗

PubMed2004

Temporal relationship of viral load, ribavirin, interleukin (IL)-6, IL-8, and clinical progression in patients with severe acute respiratory syndrome.

Although viral replication and overwhelming immune responses are believed to contribute to the progression of severe acute respiratory syndrome (SARS), little is known about the temporal relationship between viral load, ribavirin, proinflammatory cytokines, and clinical progression. We report that ribavirin was not effective in reducing the SARS coronavirus load in 3 of 8 probable cases studied and that elevated levels of interleukin (IL)-6 and IL-8 subsequent to the peak viral load were found in 8 and 6 cases, respectively. The nadir lymphocyte count during lymphopenia, the peak level of lactate dehydrogenase, and the peak density of pulmonary infiltrates lag further behind the peak viral load by a median of 4, 5, and 3.5 days, respectively. These findings provide important information for therapeutic strategies to treat SARS.

Adult↗

PubMed1996

Cytotoxic T lymphocytes in asymptomatic long-term nonprogressing HIV-1 infection. Breadth and specificity of the response and relation to in vivo viral quasispecies in a person with prolonged infection and low viral load.

Although vigorous activated and memory CTL have been associated with HIV-1 infection, data are lacking regarding the breadth of epitopes recognized in a given individual and the relationship to the viral quasispecies present in vivo. In this study we performed a detailed analysis of the HIV-1-specific CTL response in a seropositive person with documented HIV-1 infection of 15 yr duration, stable CD4 counts above 500 cells/ml, and viral load persistently below 500 molecules of RNA/ml of plasma. Epitope mapping studies revealed the presence of HLA class I-restricted CTL responses to six different epitopes in p17, p24, RT, Env, and Nef, which conferred broadly cross-reactive recognition of reported HIV-1 variants. Sequence analysis of autologous viruses revealed the absence of immune escape variants within five of the six epitopes. Despite consistently low viral RNA levels in plasma and viral DNA levels in PBMC, in vivo-activated circulating CTL were detected against three of the epitopes. Five of the six epitopes, including the three dominant epitopes, have been detected in persons with progressive disease, suggesting that nonprogressors may not target unique epitopes. This study demonstrates that HIV-1-specific CTL can be highly activated and broadly directed in the setting of an extremely low viral load, and that neither high viral load nor antigenic diversity is required for the generation of a multispecific CTL response. Although the detection of strong CTL responses, low viral load, and lack of immune escape are consistent with the hypothesis that CTL may contribute to lack of disease progression in this individual, the contribution of these responses to maintenance of the asymptomatic state remains to be determined.

Amino Acid Sequence↗