Evaluation of Xpert HIV-1 Qual assay for resolution of HIV-1 infection in samples with negative or indeterminate Geenius HIV-1/2 results

BackgroundDiagnosis of HIV infection is a multistage algorithm. Following screening with 4^th generation combination immunoassay, confirmation of HIV infection is performed with an antibody assay that differentiates HIV-1 from HIV-2 infection. In the newly updated algorithm, samples that are nonreactive or indeterminate in the differentiation assay are to be tested with an HIV-1 nucleic acid amplification (NAAT) test for resolution. Xpert HIV-1 Qual is a new NAAT assay approved for the identification of HIV infection in whole and dried blood.ObjectivesTo assess the performance of Xpert HIV-1 Qual supplementary assay in resolving the clinical status of serum samples reactive by 4^th generation immunoassays and indeterminate or negative by Geenius HIV-1/2 confirmatory assay.Study designIn a retrospective study, samples from 97 individuals for whom the true HIV-1 status was already known (by follow-up samples) and which were negative or indeterminate by HIV-1/2 Geenius assay were tested with Xpert Qual HIV-1 assay.ResultsXpert Qual assay correctly classified all 97 samples from HIV-1 positive (n = 49) and negative (n = 48) individuals. The sensitivity and specificity of Xpert Qual when using the true HIV status as a reference were 100% (92.7–100% at 95% confidence interval [CI] and 92.6–100% at 95% CI, respectively).ConclusionsApplying Xpert Qual HIV-1 assay in the new HIV multi-stage diagnostic algorithm correctly classified 100% of HIV-1 infections including 49 from HIV-1 carriers who have not yet seroconverted. With this assay the total time required for acute HIV diagnosis could be significantly reduced.     

Performance of a new rapid test for the detection of hepatitis B surface antigen in various patient populations

BackgroundRapid diagnostic tests (RDT) have been developed for the detection of hepatitis B surface antigen (HBsAg). They represent a promising alternative to enzyme immunoassays and a powerful tool for large-scale screening and diagnosis of HBV infection, especially in regions without easy access to serological and molecular testing.ObjectivesThe aims of the present study were to evaluate the characteristics and clinical performance of a new CE-marked HBsAg RDT, DRW-HBsAg v2.0 assay (Diagnostics for the Real World™, Ltd., USA), in various patient populations, including those chronically infected with HBV, patients with severe acute hepatitis of unknown origin and pregnant women with unknown HBV serological status at delivery.ResultsThe lower limit of detection of the assay, evaluated in 21 clinical samples, ranged from 0.30 ± 0.07 to 0.97 ± 0.26 international units/mL (using Abbott Architect as a reference), depending on the HBV genotype. The assay tested positive in 100% of patients with chronic hepatitis B, 96.3% of HBsAg-positive acute hepatitis patients, and 95.2% of HBsAg-positive pregnant women. Its specificity was 98.8% in HBsAg-negative patients, 98.7% in HBsAg-negative patients with acute hepatitis of unknown origin and 97.8% in HBsAg-negative pregnant women. Amino acid substitutions in the HBsAg major hydrophilic region did not affect HBsAg detection by DRW-HBsAg v2.0.ConclusionsThe new DRW-HBsAg v2.0 assay is a simple, rapid, easy-to-run and highly sensitive assay that can be used in both high- and low-risk populations for the diagnosis of HBsAg carriage. It appears to be a promising new tool for large-scale screening and diagnosis of HBV infection.     

Effect of naturally acquired type-specific serum antibodies against human papillomavirus type 16 infection

BackgroundWhile vaccine-induced antibodies are known to confer protection against incident human papillomavirus (HPV) infection, there is inconsistent data regarding the protective effect of naturally acquired anti-HPV antibodies.ObjectivesTo estimate the protective effect of naturally acquired anti-HPV16 serum antibodies against incident anogenital infection with HPV16 in females aged 20–64 years and to assess whether antibodies influence the persistence/clearance of anogenital HPV16 infection.Study design4432 women attending the organized national cervical cancer screening program in Slovenia were initially enrolled. 2199 and 1848 women had valid HPV DNA results obtained using PCR-based assays and HPV antibody serotyping results obtained using pseudovirion-based serological assay, at baseline and at three-year follow-up, respectively.ResultsBaseline HPV16 seroprevalence was 2.4-fold higher among HPV16 DNA-positive women (55.7% vs. 23.2%; p < 0.01). Baseline HPV16 DNA-positive/seronegative women frequently acquired anti-HPV16 antibodies during follow-up (OR = 8.2; 95% CI: 3.8–17.8). Baseline anti-HPV16 antibodies persisted at follow-up, irrespective of baseline HPV16 DNA status (OR = 40.6; 95% CI: 30.3–54.5). Baseline HPV16 DNA-negative/seropositive women were less likely to acquire HPV16 infection at follow-up (unadjusted OR = 0.2; 0.1–0.9). However, the age-adjusted association was non-significant (adjusted OR = 0.3; 0.1–1.2). The tendency for protective effect was stronger among women older than 25 years (OR = 0.2; 0.03–1.8). Baseline anti-HPV16 antibodies were not associated with persistence/clearance of HPV16 infection at follow-up (OR = 0.8; 0.3–1.9).ConclusionsNaturally acquired anti-HPV16 serum antibodies appeared to protect against anogenital HPV16 infection, but this association was at least partially confounded by age. Baseline anti-HPV16 serum antibodies did not influence persistence/clearance of HPV16 infection at follow-up.     

Seroprevalence of trichodysplasia spinulosa-associated polyomavirus in Japan

BackgroundTrichodysplasia spinulosa-associated polyomavirus (TSV) was identified in, and shown to be the probable cause of, trichodysplasia spinulosa, a rare skin disease. To date, serological analyses have revealed that TSV infection is common among adults in the general population of Europe and Australia. However, there have been no reports of TSV in Asia.ObjectiveTo study the prevalence of TSV infection in Japan.Study designTSV-VP1 expressed in a recombinant baculovirus expression system in an insect cell line, Tn5, self-assembled into virus-like particles. Overall, 1000 serum samples were examined by enzyme-linked immunosorbent assays using virus-like particles of TSV as antigen. Participants ranged in age from 0 to 94 years.ResultsOverall, 629 of 1000 serum samples (62.9%) were positive for anti-TSV antibodies. The seropositive rate increased with age and the seroprevalence of TSV significantly increased from 17.1% (25/146) in children aged from 0 to 4 years to 78.7% (472/600) in adults aged over 20 years (odds ratio = 0.056, 95% confidence interval = 0.035–0.900, P = 0.000, Chi-squared test). TSV seropositivity was not different between sera obtained in 1980 and 2012, and was not associated with sex. Competitive assay demonstrated that TSV antibodies did not cross-react with BK virus or Merkel cell polyomavirus.ConclusionsThese results provide evidence that TSV circulates widely in the Japanese population, with primary exposure occurring mainly at early childhood, similar to that previously reported in other countries.     

Performance of an antigen assay for diagnosing acute hepatitis E virus genotype 3 infection

BackgroundHepatitis E virus (HEV) is a major cause of hepatitis worldwide. Its diagnosis is based on the detection of anti-HEV IgM and/or HEV-RNA.ObjectiveTo evaluate the performance of the Wantaï HEV-antigen (Ag) ELISA^Plus assay for diagnosing acute HEV infections.Study designSpecificity was assessed using 100 blood samples containing no anti-HEV IgM, anti-HEV IgG, or HEV-RNA. Cross reactivity was assessed using samples positive for hepatitis C virus RNA (n = 10), Epstein-Barr virus DNA (n = 10) and cytomegalovirus DNA (n = 10). Serial dilutions of 4 HEV RNA positive samples were used to estimate the corresponding viremia detected with the Ag assay. Blood samples from 33 immunocompetent and 31 immunocompromised patients with an acute HEV genotype 3 infection, HEV-RNA positive, were tested to assess diagnostic sensitivity.ResultsThe HEV-Ag assay was 100% specific, with no cross-reactivity. The lower viremias detected ranged from 10³ copies/ml to 10⁵ copies/ml (800–80,000 UI/ml). Diagnostic sensitivity for an acute HEV infection was 91%, with no significant difference between immunocompetent (88%) and immunocompromised (94%) patients. The HEV-Ag assay was more frequently positive in immunocompromised patients at the acute phase (94%) than was the anti-HEV IgM test (71%; p = 0.04). The HEV-Ag assay ratio was correlated with HEV-RNA viral load (ρ = 0.54; p < 0.0001).ConclusionThe HEV-Ag assay performed well and could be suitable for laboratories with no molecular diagnosic facilities.     

Antigen-specific H1N1 influenza antibody responses in acute respiratory tract infections and their relation to influenza infection and disease course

BackgroundEarly antibody responses to influenza infection are important in both clearance of virus and fighting the disease. Acute influenza antibody titers directed toward H1-antigens and their relation to infection type and patient outcomes have not been well investigated.ObjectiveUsing hemagglutination inhibition (HI) assays, we aimed to characterize the H1-specific antibody titers in patients with influenza infection or another respiratory infection before and after the H1N1-pandemic influenza outbreak. Among patients with acute influenza infection we related duration of illness, severity of symptoms, and need for hospitalization to antibody titers.MethodsThere were 134 adult patients (average age 34.7) who presented to an urban academic emergency department (ED) from October through March during the 2008–2011 influenza seasons with symptoms of fever and a cough. Nasal aspirates were tested by viral culture, and peripheral blood serum was run in seven H1-subtype HI assays.ResultsAcutely infected influenza patients had markedly lower antibody titers for six of the seven pseudotype viruses. For the average over the seven titers (log units, base 2) their mean was 7.24 (95% CI 6.88, 7.61) compared with 8.60 (95% CI 8.27, 8.92) among patients who had a non-influenza respiratory illness, p < 0.0001. Among patients with seasonal influenza infection, titers of some antibodies correlated with severity of symptoms and with total duration of illness (p < 0.02).ConclusionIn patients with acute respiratory infections, lower concentrations of H1-influenza-specific antibodies were associated with influenza infection. Among influenza-infected patients, higher antibody titers were present in patients with a longer duration of illness and with higher severity-of-symptom scores.     

Serum antibodies to human papillomavirus (HPV) pseudovirions correlate with natural infection for 13 genital HPV types

BackgroundSerology for human papillomaviruses (HPV) types -16 and -18 is established as an important tool for studies of HPV vaccinology and epidemiology. However, as there are a large number of oncogenic genital types of HPV there is a need for development of high-throughput, validated HPV serological assays that can be used for more comprehensive seroepidemiological studies and for research on multivalent HPV vaccines.ObjectivesTo develop a multiplexed pseudovirion-based serological assay (PsV-Luminex) encompassing 21 HPV types and validate the method by correlating the serology with the presence of type specific HPV DNA in cervical samples.Study designCervical swabs from 3,291 unvaccinated women attending organized cervical screening in Slovenia were tested with 3 different HPV DNA detection methods and presence of HPV DNA compared to presence of serum antibodies to pseudovirions from 15 genital HPV types (HPV-6,-11,-16,-18,-31,-33,-35,-39,-45,-52,-56,-58,-59,-68,-73).ResultsOn average 51% of the HPV DNA positive women were seropositive for the same HPV type that was detected in the cervical specimen. We found a strong correlation with presence of HPV DNA and antibodies to the same HPV type for 13/15 genital HPV types (median OR = 5.7, CI 95% = 2.4–12.9). HPV-52 serology failed the validation and HPV-11 serology could not be validated because only a single woman was positive for HPV-11 DNA. The correlation between serology and HPV DNA status tended to be stronger among women infected with single HPV type (median OR = 10.5, CI 95% = 2.4–48.4) than among women with multiple HPV infections (median OR = 4.6, CI 95% = 1.8–11.7).ConclusionsA multiplexed HPV PsV-Luminex assay has been developed and validated to correlate with natural HPV infection for 13 HPV types, thus enabling more comprehensive studies in HPV epidemiology and vaccine research.     

Detection and differentiation of HIV-2 using the point-of-care Alere q HIV-1/2 Detect nucleic acid test

BackgroundThe Alere q HIV-1/2 Detect test (Alere Detect) is a rapid point-of-care (POC) nucleic acid test (NAT) that can detect and differentiate HIV-1 and HIV-2 in 25-μL whole blood or plasma samples. The Alere Detect test has been validated for early infant diagnosis of HIV-1 infection, and it is the only POC NAT device currently known to detect HIV-2, which is endemic in West Africa.ObjectivesTo evaluate the sensitivity detecting HIV-2 RNA and the differential performance of the Alere Detect.Study designPlasma samples from non-HIV (n = 4), HIV-1 (n = 22), HIV-2 (n = 111; 29 Group A, 2 Group B) and HIV-1/HIV-2 dually-seropositive (n = 8) participants in Senegal and the United States and HIV-2 reference strains (3 Group A, 1 Group B) were tested by Alere Detect, Abbott RealTime HIV-1 and the University of Washington HIV-2 RNA quantitative (UW HIV-2) assays.ResultsThe Alere Detect correctly differentiated between HIV-1 and HIV-2 in all 80 (100%) patient samples with detectable HIV RNA (n = 20 HIV-1, 60 HIV-2). The overall HIV-2 detection concordance between Alere Detect and the UW HIV-2 assay was 68% (54/80); the concordance improved to 100% (30/30) for samples with HIV-2 RNA >300copies/mL. Neither assay detected HIV-2 RNA in 31 of 111 HIV-2 seropositive samples.ConclusionsThe Alere Detect test is a novel device detecting HIV RNA in clinical samples, and differentiating HIV-1 and HIV-2 with a high level of specificity. It has the potential for use as a rapid HIV-2 NAT-based diagnosis tool in resource-limited settings and to confirm HIV-2 infection for the CDC 4th generation HIV-1/2 diagnostic algorithm.     

Clinical presentation and response to treatment of novel influenza A H1N1 in a university-based summer camp population

BackgroundLittle is known about the clinical presentation and course of novel H1N1 influenza in summer camps.ObjectivesTo describe the clinical course and evaluate the effect of influenza treatment in a summer camp population.Study designTwo large influenza outbreaks occurred in university-based residential camps between May 21 and August 2, 2009. Through active daily surveillance, medical evaluation at symptom onset, and data collection during isolation, we describe the clinical course of a large outbreak of novel H1N1 influenza.ResultsInfluenza-like illness (ILI) was documented in 119 individuals. Influenza A was confirmed in 66 (79%) of 84 samples tested. Three early samples were identified as novel H1N1. ILI cases had an average age of 15.7 years and 52% were male. Sixty-three were treated with oseltamivir or zanamivir, which was initiated within 24 h of diagnosis. Cough, myalgia and sore throat occurred in 69, 64 and 63% of cases, respectively. The highest temperature over the course of illness (T_max) occurred within 48 h after symptom onset in 87.5% of individuals. Average T_max was 38.4 °C (range 36.1–40.2 °C). Among confirmed influenza cases, 69% defervesced by 72 h and 95% defervesced by 96 h. Defervescence at 72 h was not different in the treated and untreated groups (p = 0.12).ConclusionsNovel H1N1 generally has a mild, self-limited course in healthy adolescent campers. Defervescence occurred within 72 h and was unaffected by treatment.     

Detection and quantification of HIV-1 RNA with a fully automated transcription-mediated-amplification assay

BackgroundNucleic acid testing is the major method used to monitor HIV viral load. Commercial systems based on real-time PCR assays are available for high-volume centralized laboratory testing, but they are not fully automated.Objectives and study designWe have compared the diagnostic performance of the Hologic Aptima HIV-1 Quant Dx assay (Aptima) (based on real-time TMA) on the Panther instrument, a fully-automated random access platform, to that of, the Roche Cobas Ampliprep Cobas TaqMan (CAP/CTM) HIV-1 version 2.0 (based on real-time PCR).ResultsProbit analysis of replicate dilutions of NIBSC WHO International HIV-1 Standard, gave LODs of 8.6 c/ml for Aptima and 15.2 c/ml for CAP/CTM. The agreement between the assays was excellent when measuring HIV RNA in a calibrated reference (κ = 0.90, p < 0.001) and good when measuring clinical samples (κ = 0.62, p < 0.001). The correlation among the samples quantified by the two methods was very good (r = 0.95, p< 0.001) and the mean difference between the values obtained with the two assays was 0.02 log c/ml for B and non-B subtypes. The vast majority of results showed <0.5 log variance between the two assays (89%); only one sample showed results that differed by over 1.0 log c/ml.ConclusionThe performance of the new fully automated Aptima assay is adequate for clinical monitoring of HIV-1 RNA during infections and treatment. The Aptima assay is well suited for routine laboratory use.     

Kinetics of cytokine and chemokine responses in patients with primary human herpesvirus 6 infection

BackgroundCytokines and chemokines induced by human herpesvirus 6 (HHV-6) infection may play an important role in the observed HHV-6-associated clinical complications. However, basic data for cytokine and chemokine synthesis in primary HHV-6 infected patient without complication is lacking.ObjectiveAim of this study was to elucidate basic kinetic data for expressions of cytokines and chemokines in patients with primary HHV-6 infection without complication.Study designTwenty-six patients suffering from fever were enrolled in this study. Fourteen biomarkers were measured in 74 serially collected sera samples from 26 patients. Additionally, serum samples obtained from 14 healthy children were used for control.ResultsTwenty of the 26 patients were diagnosed with primary HHV-6 infection based on viral isolation and serological analysis. The mean age (P = 0.1289) and proportion of males to females (P = 0.9999) between the patients with and without primary HHV-6 infection were not statistically different. At the acute phase of the disease, three cytokines (IFN-γ; P = 0.0046, IL-2; P = 0.0366, and IL-4; P = 0.0255) and one chemokine (MCP-1; P = 0.0019) were significantly higher in patients with primary HHV-6 infection compared to those without infection. Interleukin-5 levels during the convalescent period were significantly higher in patients with HHV-6 infection (P = 0.0205). By 1 month post-infection, cytokine and chemokine expression had returned to almost basal levels.ConclusionAs suggested by the previous in vitro studies, present in vivo analysis also suggests that HHV-6 has potency for induction of cytokines and chemokines.     

Performance of a rapid antigen test (Binax NOW® RSV) for diagnosis of respiratory syncytial virus compared with real-time polymerase chain reaction in a pediatric population

BackgroundInfants from Alaska's Yukon–Kuskokwim Delta (YKD) have a high respiratory syncytial virus (RSV) hospitalization rate (104/1000/yr). Appropriate patient management requires rapid and accurate RSV diagnosis. Antigen-based methods are often used in clinical settings, but these tests can lack sensitivity.ObjectiveWe compared Binax NOW^® RSV (BN) used for RSV diagnosis in the YKD hospital with a real-time polymerase chain reaction assay (RT-qPCR) used for viral surveillance.Study designBetween October 2005 and September 2007 we obtained nasopharyngeal washes (NPW) from children <3 years hospitalized with a lower respiratory tract infection. The NPW were tested using BN and RT-qPCR.Results79/311 (25%) children had RSV infection as determined by RT-qPCR. As compared with RT-qPCR, sensitivity and specificity of BN were 72% and 97%, respectively. The sensitivity of BN was higher in children <1 year compared with children ≥1 year (79% vs. 52%; p = 0.025), children with bronchiolitis compared with children without bronchiolitis (89% vs. 38%; p < 0.001), and children with a shorter duration of symptoms before testing (0–1 (92%) vs. 2–4 (78%) vs. 5+ (65%) days; p = 0.04). The median RSV viral load in NPW positive by BN and RT-qPCR was 1.01 × 10⁹ copies/mL vs. a median of 5.25 × 10⁷ copies/mL for NPW positive by RT-qPCR only (p < 0.001).ConclusionRT-qPCR is more sensitive than BN in detecting RSV infection. BN sensitivity is high in children with bronchiolitis, but the sensitivity is low when children present with a non-bronchiolitis illness, especially after a longer duration of symptoms before testing.     

Performance comparison of the 4th generation Bio-Rad Laboratories GS HIV Combo Ag/Ab EIA on the EVOLIS™ automated system versus Abbott ARCHITECT HIV Ag/Ab Combo,Ortho Anti-HIV 1 + 2 EIA on Vitros ECi and Siemens HIV-1/O/2 enhanced on Advia Centaur

BackgroundA multisite study was conducted to evaluate the performance of the Bio-Rad 4th generation GS HIV Combo Ag/Ab EIA versus Abbott 4th generation ARCHITECT HIV Ag/Ab Combo. The performance of two 3rd generation EIAs, Ortho Diagnostics Anti-HIV 1 + 2 EIA and Siemens HIV 1/O/2 was also evaluated.ObjectiveStudy objective was comparison of analytical HIV-1 p24 antigen detection, sensitivity in HIV-1 seroconversion panels, specificity in blood donors and two HIV false reactive panels.Study designAnalytical sensitivity was evaluated with International HIV-1 p24 antigen standards, the AFFSAPS (pg/mL) and WHO 90/636 (IU/mL) standards; sensitivity in acute infection was compared on 55 seroconversion samples, and specificity was evaluated on 1000 negative blood donors and two false reactive panels.ResultsGS HIV Combo Ag/Ab demonstrated better analytical HIV antigen sensitivity compared to ARCHITECT HIV Ag/Ab Combo: 0.41 IU/mL versus 1.2 IU/mL (WHO) and 12.7 pg/mL versus 20.1 pg/mL (AFSSAPS); GS HIV Combo Ag/Ab EIA also demonstrated slightly better specificity compared to ARCHITECT HIV Ag/Ab Combo (100% versus 99.7%). The 4th generation HIV Combo tests detected seroconversion 7–11 days earlier than the 3rd generation HIV antibody only EIAs.ConclusionBoth 4th generation immunoassays demonstrated excellent performance in sensitivity, with the reduction of the serological window period (7–11 days earlier detection than the 3rd generation HIV tests). However, GS HIV Combo Ag/Ab demonstrated improved HIV antigen analytical sensitivity and slightly better specificity when compared to ARCHITECT HIV Ag/Ab Combo assay, with higher positive predictive values (PPV) for low prevalence populations.     

Measuring human immunodeficiency virus type 1 RNA loads in dried blood spot specimens using NucliSENS EasyQ HIV-1 v2.0

BackgroundHIV-1 RNA plasma level is a key parameter for anti-viral treatment monitoring in HIV-1 infected individuals. Plasma stability and accurate measurement of clinical state is at risk when transporting from remote areas. Dried blood spot (DBS) testing can reduce this risk.ObjectivesDetermine the performance of NucliSENS EasyQ HIV-1 v2.0 for DBS.Study design100 HIV-1 negative, and 129 HIV-1 spiked blood specimens (2180 copies/ml) were used for diagnostic specificity and system robustness. Analytical performance was tested in the range 50–85,000,000 copies/ml. Clinical reactivity was measured with specimens obtained from 224 HIV-1 infected individuals. HIV-1 RNA stability was analyzed after applying several different storage conditions.ResultsDiagnostic specificity was 100% and system robustness was demonstrated by 100% detection rate without invalids. Limit of detection (95% detection rate) was 800 copies/ml. Linear results were obtained over the whole range tested. For clinical specimens, percentage positive results were comparable for DBS (57%) and plasma (58%). DBS quantification was on average 0.36 log 10 lower as compared to plasma. Specimen stability was demonstrated for 1 week at 55 °C/60% humidity, 3 weeks at 37 °C/80% humidity, 9 weeks at 37 °C/40% humidity, 3 months at ?20 °C/70% humidity, 3 weeks at 4 °C/100% humidity, 9 months at room temperature (15–30 °C), and 9 weeks shipment simulation.ConclusionResults obtained fully support the use of DBS for the NucliSENS EasyQ HIV-1 v2.0 assay. These findings are especially of importance in cases that plasma stability is currently at risk due to for example, long transport routes from remote areas under less controlled conditions.     

Evaluation of the Bio-Rad Multispot HIV-1/HIV-2 Rapid Test as an alternative to Western blot for confirmation of HIV infection

BackgroundIn the United States, a new HIV diagnostic algorithm has been proposed that uses an HIV-1/HIV-2 antibody differentiation immunoassay instead of Western blot or immunofluoresence for confirmatory testing.ObjectivesTo evaluate the Multispot HIV-1/HIV-2 Rapid Test (Multispot) as an alternative to Western blot analysis for confirmation of HIV infection.Study designA series of 205 serum and plasma specimens positive for HIV-1 or HIV-2 were used to compare the performance of Multispot to a standard HIV-1 Western blot. Positive samples included 63 specimens from patients > 18 months of age, 33 proficiency survey specimens, and 109 specimens from nine commercial seroconversion and performance panels. In addition, 63 specimens from 51 HIV-exposed, uninfected children ≤ 18 months of age in various stages of seroreversion and 192 HIV-negative samples were tested. Specimens were initially screened using a 4th generation HIV Ag/Ab Combo assay.ResultsMultispot readily discriminated between individuals with HIV-1 or HIV-2 infection and those who were uninfected. Of the 205 samples repeatedly reactive by the 4th generation screening assay, infection status was correctly confirmed by Multispot in 83.9% (172/205) compared to 68.8% (141/205) for Western blot. Multispot detected HIV-1 earlier in 27.6% of low-titer antibody specimens called indeterminate by Western blot, and effectively reduced the number of indeterminate results in seroreverting HIV-1 exposed, uninfected infants and for HIV-2 infections misinterpreted as indeterminate or positive by HIV-1 Western blot.ConclusionsMultispot offers speed and simplicity over Western blot and has an excellent performance for differentiation and confirmation of antibodies to HIV-1 and HIV-2.     

Quantification of cytomegalovirus DNA by a fully automated real-time PCR for early diagnosis and monitoring of active viral infection in solid organ transplant recipients

BackgroundQuantification of cytomegalovirus (CMV) DNA by real-time PCR is currently considered an alternative diagnostic approach for the evaluation of active infection in transplant patients. The pp65 antigenemia assay has been used as reference test for monitoring active CMV infection and guiding preemptive therapy in transplant recipients. However, this assay suffers from some limitations: need for immediate processing of the samples, labour-intensive process, lack of standardization and subjective result interpretation.ObjectivesThe aim of this study was to evaluate the performance of a new commercially available real-time PCR assay coupled with a fully automated DNA extraction system (COBAS Ampliprep/COBAS Taqman CMV Test, Roche Diagnostics) for the detection of CMV-DNA in plasma comparing it with pp65 antigenemia assay for monitoring active CMV infection in solid organ transplant recipients (SOTRs).Study designA total of 266 consecutive samples from 45 SOTRs were monitored with pp65 antigenemia and in parallel with CMV-DNA quantitation by real-time PCR assay.ResultsFifty-eight samples resulted PCR-positive, 163 negative and for 45 samples the CMV-DNA values obtained were below the lower limit of quantification (<150 copies/ml); pp65 antigen was detected in 47 samples and resulted negative in 219 specimens. Concordance between the two evaluations was 76.7%; also a good correlation was observed (r = 0.718). Considering the existing treatment criteria based on pp65 antigenemia evaluation corresponding to pp65 levels ≥ 20 positive cells/200,000, preemptive therapy was administered to four asymptomatically infected patients. The corresponding cut-off value of CMV-DNA load calculated for discrimination between self-clearing infections and those requiring therapy was 2500 copies/ml (or 2275 IU/ml).ConclusionThe fully automated real-time PCR from Roche provided specific and sensitive results and represented a rapid and simple assay for the evaluation and monitoring of CMV infection in SOTRs. Further studies are required to validate the threshold level for the initiation of preemptive therapy.     

Keratoconjunctivitis sicca of human T cell lymphotropic virus type 1 (HTLV-1) infected individuals is associated with high levels of HTLV-1 proviral load

BackgroundA high HTLV-1 proviral load is found in HTLV-1-associated diseases, mainly HAM/TSP. However, the association between proviral load and keratoconjunctivitis sicca (KCS) has not been well established.AimTo verify the association between KCS and HTLV-1 proviral load.Study design104 HTLV-1 infected patients (51 asymptomatic and 52 with HAM/TSP) from the HTLV reference center in Salvador, Brazil were followed from June 2008 to May 2010. Evaluation of tear secretion was performed by BUT (break-up time), Rose Bengal and Schirmer I tests. The diagnosis of KCS was based upon the presence of symptoms and when at least two of three tests were positive. HTLV-1 proviral load was determined using real-time PCR.ResultsThe prevalence of KCS was 44.2%. KCS was more frequent among HAM/TSP patients (p = 0.022). Patients with KCS had higher proviral load (mean 134,672 ± 150,393 copies/10⁶ PBMC) than patients without the disease (mean 66,880 ± 109,525 copies/10⁶ PBMC) (p = 0.001). HTLV-1 proviral load > 100,000 copies/10⁶ PBMC increased significantly the risk of developing KCS (OR = 4.05 and 95% CI = 1.40–11.76). After age > 45 years and HAM/TSP status were excluded in stepway reward analysis, the variables PVL > 100,000 (OR = 4.77 and 95% CI = 1.83–12.44) still remained statistically significant.ConclusionHTLV-1 proviral loads are higher in patients with KCS and may represent a relevant biological marker of disease.     

Diagnostic usefulness of dynamic changes of CMV-specific T-cell responses in predicting CMV infections in HCT recipients

BackgroundCMV-specific cell mediated immune responses before and after hematopoietic stem cell transplantation (HCT) can categorize patients as at high or low risk of CMV development.ObjectivesWe evaluated the usefulness of the CMV-specific T-cell ELISPOT assay for predicting the development of CMV infections after HCT in recipients with donor-positive and recipient-positive CMV serology (D+/R+ ).Study designCMV pp65 and IE1-specific ELISPOT assays were performed before HCT (D0), and at 30 (D30) and 90 (D90) days after HCT.ResultsOf the 84 HCT recipients with D+/R+, 42 (50%) developed ≥ 1 episode of CMV infection. Thirty-nine (64%) of 61 patients with Δ(D30-D0) pp65 < 42 developed CMV infections compared with 3 (14%) of 21 patients with Δ(D30-D0) pp65 ≥ 42 (P < 0.001). Twenty-three (74%) of 31 patients with Δ(D30-D0) IE1 < −4 developed CMV infections compared with 19 (37%) of 51 patients with Δ(D30-D0) IE1 ≥ −4 (P = 0.001). pp65 Δ(D30-D0) ≥ 42 had 93% sensitivity for ruling out subsequent CMV infection, and pp65 Δ(D30-D0) < 42 followed by Δ(D30-D0) IE1 < −4 had 100% specificity for ruling in the subsequent CMV infection. In addition, 10 (53%) of 19 patients with Δ(D90-D30) pp65 < 23 had relapsing CMV infections, compared with 3 (15%) of 20 patients with Δ(D90-D30) pp65 ≥ 23 (P = 0.02). The sensitivity and specificity of Δ(D90-D30) pp65 were 77% (95% CI 50–92) and 65% (95% CI, 46–81).ConclusionDynamic change in the CMV-specific ELISPOT assay before versus after HCT appears to predict the subsequent development of CMV infection and relapsing CMV infection.     

Diagnostic performance of serological assays for anti-HBs testing: Results from a quality assessment program

BackgroundPost-vaccination testing after hepatitis B vaccination is indispensable to evaluate long-term immunological protection. Using a threshold level of antibodies against hepatitis B surface antigen (anti-HBs) to define serological protection, implies reproducible and valid measurements of different diagnostic assays.ObjectivesIn this study we assess the performance of currently used anti-HBs assays.Study designIn 2013, 45 laboratories participated in an external quality assessment program using pooled anti-HBs serum samples around the cutoff values 10 IU/l and 100 IU/l. Laboratories used either Axsym (Abbott Laboratories), Architect (Abbott Laboratories), Access (Beckman-Coulter), ADVIA Centaur anti-HBs2 (Siemens Healthcare Diagnostics), Elecsys, Modular or Cobas (Roche Diagnostics) or Vidas Total Quick (Biomerieux) for anti-HBs titre quantification. We analysed covariance using mixed-model repeated measures. To assess sensitivity/specificity and agreement, a true positive or true negative result was defined as an anti-HBs titre respectively above or below the cutoff value by ≥4 of 6 assays.ResultsDifferent anti-HBs assays were associated with statistically significant (P < 0.05) differences in anti-HBs titres in all dilutions. Sensitivity and specificity ranged respectively from 64%-100% and 95%-100%. Agreement between assays around an anti-HBs titre cutoff value of 10 IU/l ranged from 93%-100% and was 44% for a cutoff value of 100 IU/l.ConclusionsAround a cutoff value of 10 IU/l use of the Access assay may result in false-negative results. Concerning the cutoff value of 100 IU/l, a sample being classified below or above this cutoff relied heavily on the specific assay used, with both the Architect and the Access resulting in false-negative results.