Concomitant increases in CXCL13 and IL-21 were significant in HBeAg-negative CHB patients who attained HBsAg seroconversion with sequential therapy (consisting of a combination of Nucs and subsequent pegIFN-α (48 weeks)) while increases in CXCL13 and IL-21 were not observed in CHB patients who failed to attain HBsAg loss, even during hepatitis flares [133]. This evidence concerns the gene IL21 and hepatitis A virus infection.