[Hepatitis B virus genotypes]

Impact of the Universal Implementation of Adolescent Hepatitis B Vaccination in Spain

The aim of this study was to analyse the impact of the introduction of universal adolescent HBV vaccination on the incidence of acute hepatitis B virus (HBV) infections. Acute HBV cases reported to the Spanish National Epidemiological Surveillance Network between 2005 and 2021 were included. For regions starting adolescent vaccination in 1991-1993 and in 1994-1996, HBV incidence rates were compared by calculating the incidence rate ratio (IRR) and 95% confidence interval (CI). We also analysed the 2017 Spanish national seroprevalence survey data. The overall acute HBV incidence per 100,000 persons was 1.54 in 2005 and 0.64 in 2021 (p < 0.001). The incidence in 2014-2021 was lower for regions that started adolescent vaccination in 1991-1993 rather than in 1994-1996 (IRR 0.76; 95% CI 0.72-0.83; p < 0.001). In the 20-29 age group, incidence in regions that started adolescent vaccination in 1991-1993 was also lower (IRR 0.87; 95% CI 0.77-0.98; p = 0.02 in 2005-2013 and IRR 0.71; 95% CI 0.56-0·90; p < 0.001 in 2014-2021). Anti-HBc prevalence in the 35-39 age group was lower in the regions that started vaccination earlier, although the difference was not statistically significant (p = 0.09). Acute HBV incidence decreased more in the young adult population in regions that began adolescent vaccination earlier. Maintaining high universal vaccination coverage in the first year of life and in at-risk groups is necessary to achieve HBV elimination by 2030.

Prevalence of HBV genotypes in Central and Eastern Europe

The importance of hepatitis B virus (HBV) genotypes for disease progression and response to interferon-alpha-based treatment is well established. While almost all patients in the Mediterranean area are infected with HBV genotype D, HBV genotype A is dominant in Northern Europe. However, the distribution of HBV genotypes is unknown for several Central and Eastern European countries. Data are described of 1313 HBsAg-positive patients recruited at 14 referral centers in eight countries. There were only very few cases of HBV genotype B, C, E, F, and H infection while HBV genotypes A and D were found in 42% and 48% of patients, respectively. Eight percent of patients had positive bands for more than one genotype using the hybridization assay. The frequency of genotype A was higher in Poland (77%) and the Czech Republic (67%) as compared to Hungary (47%), Lithuania (41%), Croatia (8%), and Germany (32%). In contrast, HBV genotype D was most frequent in Croatian, Romanian, and Russian patients with 80%, 67%, and 93% of cases, respectively. In conclusion, HBV genotype A versus D showed significantly different distribution patterns in Central and Eastern Europe which deserves consideration for national guidelines and treatment decisions.

Determinación del genotipo del virus de la hepatitis B y detección de mutaciones de resistencia al tratamiento con lamivudina

OBJECTIVES

To determine hepatitis B virus (HBV) genotypes in southern Seville (Spain) and investigate the development of lamivudine-resistance mutations by using a hybridization technique with specific probes and by comparing the results with those of the direct sequencing technique. To evaluate the temporal relationship between variations in the level of HBV-DNA and detection of mutant variants. To analyze the influence of several genotypes on the pattern of mutations developed and on values of viral load and alanine aminotransferase (ALT) after their development.

PATIENTS AND METHOD

In 37 patients with chronic HBV infection, HBV genotype was determined using the LiPA technique. In 10 of these patients undergoing lamivudine treatment for a mean of 19.2 months, the development of lamivudine-resistant mutations was investigated. In these 10 patients, the LiPA technique was compared with direct sequencing. During lamivudine treatment, we determined HBV-DNA by polymerase chain reaction (PCR) and ALT every 3-6 months.

RESULTS

The most frequent genotypes were D (45.9%) and A (18.9%); 2 patients were genotype B while 18.9% had mixed genotypes. Sequencing showed identical results except in one mixed genotype. Mutations were found in 60% of the cases. The results of sequencing were in agreement, except in the detection of mixed populations composed of mutants and wild-type (WT). Patients with genotype A showed the pattern M204I+WT in the first 12 months and those with genotype D showed the pattern L180M+M204V with or without WT at 18 months. In 5/6 cases, an increase of > 1 log10 in HBV-DNA was observed 3-8 months before the mutation was detected by LiPA. In patients with genotype B, levels of HBV-DNA and ALT after the development of mutations was lower than basal levels and was also lower than those in patients with genotypes A and D.

CONCLUSIONS

The LiPA technique for determination of HBV genotype and detection of lamivudine-resistance mutations shows excellent correlation with the most complex sequencing technique. Genotype D predominates in southern Seville. During lamivudine treatment, an increase in the level of HBV-DNA detected by PCR predicts the development of mutations before these are demonstrated by LiPA.