Strategic approach to produce low-cost, efficient, and stable competitive internal controls for detection of RNA viruses by use of reverse transcription-PCR.

Molecular diagnostics based on reverse transcription (RT)-PCR are routinely complicated by the lack of stable internal controls, leading to falsely negative results. We describe a strategy to produce a stable competitive internal control (CIC) based on a Qbeta phage derivative (recombinant Qbeta [rQbeta]) bearing primers KY78 and KY80, which are widely used in the detection of hepatitis C virus (HCV). rQbeta was RNase resistant and stable at 4 degrees C for 452 days in SM medium (0.1 M NaCl, 8 mM MgSO(4).7H(2)O, 50 mM Tris HCl [pH 7.5], 2% gelatin) and for 125 days after lyophilization and reconstitution. rQbeta performance as a CIC was evaluated. rQbeta was added to HCV-positive samples, followed by RNA extraction and a CIC-HCV RT-PCR assay. This method combines RT-PCR, liquid hybridization with nonradioactive probes, and enzyme immunoanalysis. No influence of the CIC on qualitative HCV detection was observed independently of viral load, and results had high concordance with those of commercial kits. In conclusion, we describe a versatile, low-cost alternative strategy to armored RNA technology that can be adapted for detection or real-time applications of any RNA target. Moreover, the CIC reported here is an essential reagent for HCV screening in blood banks in resource-limited settings.

[Development of slides for Epstein-Barr virus diagnosis by indirect immunofluorescence]. / Desarrollo de improntas para el diagnóstico del virus Epstein-Barr por inmunofluorescencia indirecta.

Epstein-Barr virus (EBV) is the main oncogenic lymphotropic agent of the Herpesviridae family and is globally distributed. EBV acute infection occurs in young adults producing infectious mononucleosis. Detection of anti-viral capside antigen (VCA) antibodies indicates previous or present EBV infection. Moreover, high titles of anti-VCA antibodies are observed in EBV-associated neoplasic disorders, such as lymphomas in AIDS patients. The objective of this study was the development and optimization of P3HR1 cell slides for the EBV serologic detection by indirect immunofluorescence (IIF) assay. P3HR1 exponential growth culture cells were stimulated with phorbol-12-mirystoil-13-acetate, collected at different time points and used for slide preparation. IIF assay was performed in each slide using an anti-EBV positive serum as primary antibody. An 11% increase in VCA expression was observed at 40 hours post-stimulation. Data was confirmed by Western blot and immunodetection. Intra- and inter-lot precisions of the developed slides were evaluated for IgG and IgM antibodies using EBV-positive sera and positive samples for other members of the Herpesviridae family. Neither false-positive or false negative results were obtained for EBV detection nor cross-reaction was observed with other members of the Herpesviridae family with the developed slides. In conclusion, the slides here presented can be a useful instrument for acute EBV infection diagnosis and for the serologic detection of IgG anti-VCA antibodies in EBV-associated neoplastic disorders.

[Non conventional virological markers in HIV-infected patients: T-HIV DNA, 2LTR-HIV DNA and HIV RNA]. / Marcadores virológicos no convencionales en pacientes infectados con el virus de la inmunodeficiencia humana: ADN HIV-T, ADN HIV-2LTR y ARN de HIV.

Highly active antiretroviral therapy (HAART) induces a persistent reduction of the plasmatic viremia, contributing to decrease mortality and morbidity of infected people with human immunodeficiency virus (HIV). Thus, viral load (VL) is the reference method to evaluate therapy effectiveness. However, even in the presence of efficient HAART viral eradication was yet not achieved. In this study, we analyzed the presence of total HIV DNA (T-HIV DNA), non-integrated DNA with 2LTR (2LTR-HIV DNA) and HIV RNA in a group of 55 HIV-positive subjects from Rosario City, with different clinical stages, with and without HAART. All markers were evaluated by PCR assays optimized in our laboratory that included colorimetric detection in microplate. HIV RNA clinical sensitivity was compared with a reference test, bDNA, resulting in 74% and 64% respectively, with an 85% of agreement. Thus, our HIV RNA assay could be used to monitor patients under HAART and at risk of infection. The 2LTR-HIV DNA was 54% positive although it was absent in patients with high VL. This marker was considered a labile product therefore its presence was associated with recent infection. However, current evidences question its stability. Thus, its clinical significance should be reconsidered. The absence of 2LTR-HIV DNA in patients with detectable VL may relate to the heterogeneity of the sequence used for its detection. T-HIV DNA was present in 100% of the samples and could be a relevant remission marker when therapies that effectively eradicate the infection became available.

Marcadores virologicos no convencionales en pacientes infectados con el virus de la inmunodeficiencia humana: ADN HIV-T, ADN HIV-2LTR y ARN de HIV / Non conventional virological markers in HIV-infected patients: T-HIV DNA, 2LTR-HIV DNA and HIV RNA

La terapia antirretrovial de alta eficacia (TAAE) induce una reducción marcada y persisatente de la viremia plasmática, contribuvendo a disminuir la mortalidad de los pacientes HIV-positivos. Así, la carga viral (CV) es el método de referencia para evaluar la eficacia terapéutica. Sin embargo, aun en presencia de una TAAE eficiente no se ha logrado la erradicación viral. En este estudio analizamos la presencia del ADN total de HIV (ADN HIV-T), del ADN no integrado con 2LTR (ADN HIV-2LTR) y del ARN de HIV, en un grupo de 55 pacientes HIV-positivos en distintos estadios clínicos, con y sin TAAE, mediante ensayos de PCR con revelado colorimétrico en microplaca, optimizados en nuestro laboratorio. La sensibilidad clínica de ARN del HIV fue evaluada con el bDNA, resultando del 74% y del 64%, respectivamente, con una concordancia del 85%. Este ensayo podría utilizado en el seguimiento de pacientes bajo TAAE. EI ADN HIV-2LTR resultó positivo en el 54% aunque estuvo ausente en pacientes con elevada CV. Este marcador se considereba un producto lábil y su presencia se asociaba a infección reciente. Sin embargo, actuales evidencias ponen en discusión su estabilidad por lo que su significado clínico debe ser reconsiderado. La ausencia del ADN HIV-2LTR en pacientes con CV detectable puede relacionarse con la heterogeneidade de la secuencia utilizada para su detección. EI ADN HIV-T estuvo presente en el 100% de las muestras y resultaría relevante como marcador de remisión cuando se dispongan de terapias que efectivamente erradiquen la infección.