Application of Molecular Diagnostic Techniques for Viral Testing

Cobo, Fernando

Molecular techniques can be very useful for the diagnosis of viral hepatitis infections such as hepatitis A, B, C, D and E in cases in which serological assays are no conclusive. However, currently the main application of nucleic acid test in the management of these viruses, above all hepatitis B and C, is the detection of serum or plasma viral load of these viruses for monitoring therapeutic responses of infected patients. Assays to quantify hepatitis B and C virus load in liver tissue have also been described [83, 84] . HBV DNA detection and HBV DNA viral load are also essential to explore a viral reactivation. Real-time PCR quantification assays are widely used because of their sensitivity, specificity, accuracy, broad dynamic range and positive predictive values. The World Health Organization (WHO) has defined international standards [85] . However, because of these techniques do not use the same HBV primers, follow up of patients should be carried out with the same technical assay in order to compare viral DNA load evolution. With respect to the HBV genotypes, there is currently a need to perform it due to several factors such as the prediction of clinical outcomes and the association with response to interferon treatment [86] . Genotyping of chronic HBV infections can help practicing physicians identify those at risk of disease progression and determine optimal antiviral therapy. Methods to determine the viral genotypes are based on hybridization and sequencing, and genotype affiliation rely on phylogenetic analyses.