Correlating HIV tropism with immunological response under combination antiretroviral therapy.

OBJECTIVES: A significant percentage of patients infected with HIV-1 experience only suboptimal CD4 cell recovery while treated with combination therapy (cART). It is still unclear whether viral properties such as cell tropism play a major role in this incomplete immune response. This study therefore intended to follow the tropism evolution of the HIV-1 envelope during periods of suppressive cART. METHODS: Viruses from two distinct patient groups, one with good and another one with poor CD4 recovery after 5 years of suppressive cART, were genotypically analysed for viral tropism at baseline and at the end of the study period. RESULTS: Patients with CCR5-tropic CC-motif chemokine receptor 5 viruses at baseline tended to maintain this tropism to the study end. Patients who had a CXCR4-tropic CXC-motif chemokine receptor 4 virus at baseline were overrepresented in the poor CD4 recovery group. Overall, however, the majority of patients presented with CCR5-tropic viruses at follow-up. CONCLUSIONS: Our data lend support to the hypothesis that tropism determination can be used as a parameter for disease progression even if analysed long before the establishment of a poorer immune response. Moreover, the lasting predominating CCR5-tropism during periods of full viral control suggests the involvement of cellular mechanisms that preferentially reduce CXCR4-tropic viruses during cART.

Detection of enterovirus RNA in cerebrospinal fluid (CSF) using NucliSens EasyQ Enterovirus assay.

Rapid detection of enterovirus (EV) infections is essential in the management of aseptic meningitis. Molecular approaches have opened the way to such rapid, but also specific and sensitive, diagnostic tests. The aim of this study was to compare the performance of the CE marked NucliSens EasyQ Enterovirus assay with an in-house two-step RT-PCR assay using cerebrospinal fluid (CSF) and throat swab samples. In addition, specificity was tested with clinical isolates positive for viruses with clinical importance in CSF samples. For nucleic acid extraction, the NucliSens miniMAG and NucliSens magnetic extraction reagents were used. Subsequently real-time nucleic acid sequence-based amplification (NASBA) RNA amplification was performed using NucliSens EasyQ basic kit reagents and NucliSens EasyQ Enterovirus reagents. An EV-specific internal homologous control (IC) RNA was used to monitor the entire NucliSens EasyQ procedure at the individual sample level. No IC but an external inhibition control was available for the RT-PCR method. For the NucliSens EasyQ procedure, amplification and real-time detection reactions were carried out in the NucliSens EasyQ analyzer. The real-time NASBA enterovirus detection was based on NASBA amplification and real-time molecular beacon technology. Data were analyzed using the manufacturer's software on the NucliSens EasyQ analyzer. For the in-house assay, RT-PCR amplicons were detected using agarose gel analysis. The analysis of clinical samples positive for HSV-1, HSV-2, adenovirus, CMV, VZV, mumps and rhinovirus were all negative by NucliSens EasyQ Enterovirus assay. Three rhinovirus samples were, however, strongly positive in RT-PCR. A total of 141 clinical samples were retrospectively tested, including 126 cerebrospinal fluid (CSF) samples and 15 throat swabs. The 91 CSF samples were negative by both methods, 31 CSF samples and 14 throat swab samples were positive by both methods. The four CSF samples were positive by RT-PCR only. One throat swab sample was negative in NucliSens EasyQ but positive in RT-PCR. The sensitivity and specificity of both methods seem to be more or less comparable. However, the in-house RT-PCR assay appears to amplify some rhinovirus strains and should therefore not be used for throat swab samples. NucliSens EasyQ Enterovirus assay gave more invalid results than the in-house RT-PCR, which is obvious taken into account the difference in quality control between the CE marked NucliSens EasyQ Enterovirus assay and the in-house enterovirus assay. The NucliSens EasyQ procedure can be completed within 5h versus 9.5h for the RT-PCR. NucliSens EasyQ Enterovirus assay showed to be a standardized, rapid, specific, sensitive and reliable procedure for the detection of enterovirus RNA.

Low incidence of respiratory syncytial virus hospitalisations in haemodynamically significant congenital heart disease.

BACKGROUND: Haemodynamically significant congenital heart disease (CHD) is a risk factor for severe respiratory syncytial virus (RSV) disease in young children. Population based data on the incidence of RSV hospitalisations in CHD patients are needed to estimate the potential usefulness of RSV immunoprophylaxis using palivizumab. AIMS: (1) To obtain population based RSV hospitalisation rates in children <24 months of age with CHD. (2) To compare these rates with non-CHD patients and with previous studies. (3) To determine the number of patients needed to treat (NNT) with palivizumab to prevent one RSV hospitalisation. METHODS: Six year, longitudinal, population based study at an institution, which is the sole provider of primary to tertiary in-patient care for a precisely defined paediatric population. RESULTS: RSV hospitalisation rates (per 100 child-years) in CHD patients aged <6, <12, 12-24, and <24 months of age were 2.5 (95% CI 0.8 to 5.6), 2.0 (0.8 to 3.8), 0.5 (0.1 to 1.8), and 1.3 (0.6 to 2.3), respectively, and the relative risk (RR) in comparison with non-CHD patients was 1.4 (0.6 to 3.1), 1.6 (0.8 to 3.2), 2.7 (0.7 to 9.7), and 1.8 (1.0 to 3.3), respectively. NNT was between 80 (35 to 245) and 259 (72 to 2140) for various age groups. CONCLUSION: RSV hospitalisation rates in CHD patients were fourfold lower than reported from the USA. Based on these low rates and RR, unrestricted use of palivizumab does not appear to be justified in this study area.

Two-year periodicity of respiratory syncytial virus epidemics in Switzerland.

BACKGROUND: The annual respiratory syncytial virus (RSV) epidemics vary in time and severity. The aims of this study were (1) to describe the time-related pattern of RSV epidemics in Switzerland and (2) to deduce the most effective time period for administration of prophylactic measures to high-risk patients. PATIENTS AND METHODS: Descriptive study of (1) RSV hospitalizations between 1997 and 2001 at a pediatric hospital serving a population of 1 million and (2) of national RSV detection rates reported by diagnostic laboratories between 1988 and 1999. RESULTS: 497 RSV hospitalizations and 8,574 reported RSV detections occurring during four and 12 epidemics, respectively, were analyzed. There was fixed alternation of minor and major epidemics differing in the number of RSV infections (two to fourfold), evolution (median interval from onset to peak 13 weeks, range 4-13 weeks vs 8 weeks, range 7-10 weeks; p = 0.065) and median duration (26 weeks, range 24-29 weeks vs 19.5 weeks, range 18-21 weeks; p = 0.005). For minor epidemics it was estimated that a maximum of 85.6% (range, 79.4-86.6%) of annual RSV infections could be covered by a standard five-dose regimen of the monoclonal anti-RSV antibody palivizumab, if initiated in week 50. During major epidemics the most effective time of initiation would be week 43 (88.7%; range 81.9-94.6%). CONCLUSION: RSV epidemiology in Switzerland is characterized by fixed biannual variation. In the absence of active RSV surveillance, such periodicity is useful for scheduling RSV prophylaxis and for hospital resources management.

Regional impact of prophylaxis with the monoclonal antibody palivizumab on hospitalisations for respiratory syncytial virus in infants.

QUESTIONS: Palivizumab is approved in Switzerland for prevention of hospitalisation for RSV infection in children with one of the following risk factors: (1) history of prematurity < or = 35 weeks and age < or = 6 months or (2) chronic lung disease and age < or = 1 year. Regional data on the expected effectiveness of this monoclonal antibody are not available. METHODS: (1) Retrospective, descriptive, single-site study on the characteristics of RSV hospitalisations during two consecutive seasons. (2) Extrapolation of data to generate population-based estimates on the impact of palivizumb if used according to the approved indications. RESULTS: Of 242 RSV hospitalisations, 216 (89.3%) and 26 (10.7%) occurred in children without and with risk factors, respectively. Patients without and with risk factors had similar clinical courses with respect to ICU admission rate (11.6 vs. 11.5%) and rate of mechanical ventilation (3.2 vs. 3.8%). Of a total of 28 ICU admissions, 13 (46%) occurred among infants aged < or = 1 month without risk factors. Former premature infants were significantly older than patients with longer gestation (median age 7.5 vs. 3.7 months, p = 0.026). Applying the approved age criteria would have excluded 10 of 26 patients (38.5%) from eligibility for palivizumab. During the 1999/2000 RSV season, 36% of hospitalisations occurred after April 1, 2000. None of them may have been preventable had prophylaxis been started before November 1, 1999 and carried out for 5 months as recommended. In an annual birth cohort of 10,000, palivizumab as indicated would be expected to prevent between 5 and 7 RSV hospitalisations. CONCLUSIONS: The impact of palivizumab on the prevention of RSV hospitalisations in the Canton of Bern, Switerland, is expected to be small, and the approved indications may not target infants at greatest risk for severe disease.

Detection by PCR of enteroviruses in cerebrospinal fluid during a summer outbreak of aseptic meningitis in Switzerland.

Enteroviruses (EV) are among the most common causes of aseptic meningitis. Standard diagnostic techniques are often too slow and lack sensitivity to be of clinical relevance. EV RNA can be detected within 5 h by a commercially available reverse transcription-PCR (RT-PCR) test kit. Cerebrospinal fluid (CSF) samples from 68 patients presenting with aseptic meningitis during a summer outbreak in Switzerland were examined in parallel with cell culture and commercial RT-PCR. RT-PCR was positive in all 16 CSF specimens positive by cell culture (100%). In addition, 42 of 52 (80%) CSF samples negative by cell culture were PCR positive. In 26 of these 42 (62%) patients, viral culture from other sites (throat swab or stool) was also positive. The CSF virus culture took 3 to 7 days to become positive. Echovirus 30 was the type most often isolated in this outbreak. The sensitivity of CSF RT-PCR based on clinical diagnosis during this aseptic meningitis outbreak in patients with negative bacterial culture results was 85%, i.e., considerably higher than the sensitivity of CSF virus culture (24%). We conclude that this commercial RT-PCR assay allows a positive diagnosis with minimal delay and may thus influence clinical decisions.

Evaluation of 2-SP transport medium for detection of Chlamydia trachomatis and Neisseria gonorrhoeae by two automated amplification systems and culture for chlamydia.

AIMS: To assess the performance of 2-sucrose-phosphate based transport medium (2-SP) for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae by an automated commercial polymerase chain reaction (PCR) and ligase chain reaction (LCR) compared to centrifugation culture on McCoy cells for C trachomatis. Second, to compare both amplification systems for initial diagnostic testing of a low prevalence population for sexually transmitted diseases. METHODS: Four hundred and eighty one consecutive urogenital and conjunctival specimens were examined. All tests were performed on the same specimen collected with a dacron swab and transported in 2-SP medium. Samples that were positive by culture or by both PCR and LCR were considered to be true positives. RESULTS: The prevalences of C trachomatis and of N gonorrhoeae were 2.7% and 0.4%, respectively. PCR had a resolved sensitivity and specificity of 100% and 99.8%, respectively, for C trachomatis, and 100% and 98.9%, respectively, for N gonorrhoeae. LCR was 100% sensitive and specific for both pathogens. The resolved sensitivity of the shell vial assay was 85%. No culture positive sample would have been missed by PCR or LCR. The inhibition rate for PCR was 4.8%. CONCLUSIONS: 2-SP medium proved to be suitable for both PCR and LCR. It is not limited to any one test manufacturer and allows the performance of amplification techniques and viral and chlamydia culture from the same specimen. The LCR was more reliable than PCR on initial testing. However, hands on time is longer, and no amplification control is available for LCR.

Diagnostic implications of kinetics of immunoglobulin M and A antibody responses to Toxoplasma gondii.

We evaluated immunoglobulin M (IgM) and IgA assays that could improve the predictive value for recently acquired toxoplasma infection for patients with positive screening test results. Follow-up sera were collected from 82 patients whose initial serum specimen had a reactive anti-Toxoplasma gondii IgM result. According to the evolution of the immune response, patients were divided retrospectively into two groups: one in which a recent infection was unlikely and the other one with an evolving immune response suggestive of recent toxoplasma infection. All IgM and one of three IgA assays used in the study are suitable for screening pregnant patients, with a negative predictive value of 100%. The predictive value of positive results is much lower because of the low prevalence of acute toxoplasmosis in pregnant women and the long persistence of IgM after acute infection. In the present study, all except one IgM enzyme immunoassay remained positive well beyond 6 months after the initial sample was tested. The IgM immunofluorescence test had the shortest persistence of positivity in most cases. IgA tests were either too insensitive or remained reactive too long to be useful for screening pregnant patients. Interpreting enzyme immunoassays with modified cutoff values and the combination of two tests could improve the predictive value of positive results to about 80% in terms of recent infection.

Comparison of four enzyme immunoassays for detection of immunoglobulin M antibodies against rubella virus.

We evaluated four tests for the detection of rubella virus-specific immunoglobulin M antibodies. Primarily, consecutive serum samples were tested by two different assays. Selected panels of sera from patients with proven or likely recent rubella and false-positive and true-negative results in the two primary assays were further tested with two recently developed, fully automated techniques. The four tests were comparable in overall accuracy, but their dynamic ranges may differ considerably. Ways to optimize the predictive values are discussed. We conclude that automated assays may be used without causing significant changes in diagnostic accuracy or distortions in notifications of the incidence of rubella compared with the use of established tools.

Serodiagnosis of infectious mononucleosis by using recombinant Epstein-Barr virus antigens and enzyme-linked immunosorbent assay technology.

Four recombinant, diagnostically useful Epstein-Barr virus (EBV) proteins representative of the viral capsid antigen (p150), diffuse early antigen (p54), the major DNA-binding protein (p138), and the EBV nuclear antigen (p72) (W. Hinderer, H. Nebel-Schickel, H.H. Sonneborn, M. Motz, R. Kühbeck, and H. Wolf, J. Exp. Clin. Cancer Res. 7[Suppl.]:132, 1988) were used to set up individual enzyme-linked immunosorbent assays (ELISAs) for the qualitative and quantitative detection of immunoglobulin M (IgM) and IgG antibodies. In direct comparison with results obtained by standard immunofluorescence or immunoperoxidase assays, it was then shown that the recombinant EBV ELISAs provide the means for specific and sensitive serodiagnosis of infectious mononucleosis (IM) caused by EBV. The most useful markers in sera from such patients proved to be IgM antibodies against p54, p138, and p150. Additional positive markers for recent or ongoing IM apparently were IgG antibodies against p54 and p138. In contrast, anti-p72 IgG had a high preference for sera from healthy blood donors and, therefore, can be considered indicative of past exposure to the virus. Altogether, the individual ELISAs proved to be as specific and at least as sensitive for the diagnosis of IM as the currently available standard techniques are. Moreover, our findings suggest that, by combining individual test antigens, a workable ELISA system consisting of three assays (IgM against p54, p138, and p150; IgG against p54 and p138; and IgG against p72) can be established for the standardized rapid diagnosis of acute EBV infections.

Sensitive detection and typing of human papillomavirus DNA in gynecological cell scrapings by slot-blot hybridization.

A rapid and sensitive method for detecting and typing human papillomaviruses (HPVs) in cell scrapings is presented. DNA from scrapings is extracted and bound to nitrocellulose filters (Slot-Blot). By DNA-DNA hybridization with specific 32P-labelled HPV-probes (types 6/11 or 16/18) the patient's DNA is then analyzed for the presence of, and for the type of, HPV DNA sequences. A parallel hybridization with a human repetitive element (Alu sequence) allows quantitation of the different hybridization results. Experiments with HeLa cell DNA show that as little as 10(4) HPV sequences can be detected and typed specifically with this test. Evaluation of this test is completed within 6 to 7 days after cell collection. This Slot-Blot method was used to analyse 1330 specimens taken at the Bernese Dysplasia Outpatient Clinic. The results reveal a very high percentage (90%) of HPV-positive cases in the patient group examined.

Stimulation of tryptophan uptake into brain microvessels by D-glutamine.

The uptake of L-tryptophan into isolated porcine microvessels is increased by preincubation with L-glutamine as well as with D-glutamine. This could indicate that gamma-glutamyltranspeptidase is involved in the stimulation of uptake of large neutral amino acids into the brain observed in hyperammonemic conditions.