Study on PreS-S Gene Mutation of HBV in Occult Hepatitis B Virus Infected Persons with Positive HBsAb / 现代检验医学杂志

Objective To analyze the mutation of PreS-S region in occult hepatitis B virus(OHBV) in HBV infected persons with positive HBsAb and investigate the biological mechanisms of the special infectious model.Methods A total of 38 HB-sAb positive OBI serum samples were amplified by Nested PCR and sequenced,HBV genotype and serotype were determined.The amino acid sequences of OHBV were compared to the corresponding sequence of wild-type strains of similar genotype obtained from the GenBank database.Results PreS-S segment of 11 samples were obtained and 8 samples were sequenced successfully.Among which,5 were genotype C and 3 were genotype B.Genotype B were all serotype adw,while genotype C were 1 adw and 4 adr.The mutation rates of PreS-S region,the immunoreactive area and the major hydrophilic region (MHR) were higher in OHBV than the wild-type strains (2.6％ vs 0.8％,x2 =40.23,3.2％ vs 0.3％,x2 =52.13,3.6％ vs 0.6％,x2 =13.25,all P＜0.01) and the substitutions of I126T,Q129R,M133T,F134I,D144E,G145K in α determinant were found in OBI samples.The mutation rate of amino acids in PreS-S region was higher in genotype C than genotype B (3.5％ vs 1.2％,x2--15.98,P＜0.01),meanwhile,the mutation rates in MHR,α determinant and immunoreactive region were higher in genotype C too,but no statistical significance was attained (4.7％ vs 1.7 ％,x2 =2.96,3.6 ％ vs 2.9％,x2 =0.25,4.1％ vs 2.3％,x2 =3.59,all P ＞0.05).Conclusion Mutations in PreS-S region,especially in immunoepitope,might change the virus'immunogenicity leading to escape from immune response and cause OBI with HBsAb positive.

A study on sequence variations in preS/S regions of hepatitis B virus in occult infective patients / 中华微生物学和免疫学杂志

Objective To assess the sequence variations in preS/S regions of occult hepatitis B virus (OHB) and their relationship to severe chronic hepatic injury. MethodsWe collected samples from HBsAg negative patients, and evaluated their HBV-DNA by nest-PCR. HBV-DNA positive samples were used for analysis of preS/S region by PCR sequencing. Results Sixty-nine cases with HBV-DNA were identified in 468 cases without HBsAg. The positive percents were 16％, 8.7％, 36.4％, 18.3％ and 0％in group of only HBcAb positive, only HBeAb positive, only HBeAg positive, both HBcAb and HBsAb positive and all indexes negative, respectively. The level of HBV-DNA of OHB was significant lower than that in HBsAg positive patients. Compared with HBsAg positive controls, preS/S deletion, M1I and Q2K in preS2 region, Q129N/R/P,G185R and S210R in S region were more common in OHB. Moreover, M1I and Q2K in preS2 region, G185R and S210R in S region in OHB with severe chronic hepatic injury were more common that those in OHB without severe chronic hepatic injury. Compared with HBsAg positive patients with severe chronic hepatic injury, the level of HBV-DNA was lower, while the frequency of M1I and Q2K mutation in preS2 region, G185R and S210R in S region were more common in OHB patients with severe chronic hepatic injury. ConclusionThe virological factors were different between OHB and HBsAg positive patients. The M1I and Q2K in preS2 region, G185R and S210R in S region might be useful for prognosis evaluation of OHB patients.

Study on Hepatitis B Virus Pre-S/S Gene Mutations in Children with Chronic Hepatitis B Infection

PURPOSE: Hepatitis B virus(HBV) with various mutations has been reported. The aims of this study were to investigate the frequency and manifestation of HBV pre-S/S mutations in children with chronic hepatitis B infection. METHODS: Sera from 17 children with chronic hepatitis B infection were analyzed by direct sequencing of polymerase chain reaction amplification of HBV DNA. Results: Seventeen cases of adr type were analyzed. The deletions in HBV pre-S region were observed in 3(17.6%) of 17 cases. Of 3 deleted cases, 2 had an in-phase deletion in the pre-S1 region spanning 18 bp. Another case had a 18 bp and 3 bp deletions in the pre-S1 region. Many point mutations in HBV pre-S region were detected in all cases and these mutations were observed more frequently in the pre-S2 region than the pre-S1 region. Six point mutations in the pre-S1 region were observed. Eight point mutations in pre-S2 region were observed. Point mutations in the S region were detected in 14(82.4%) of 17 cases. Among these, mutations of the "a" determinant were detected in 4(23.5%) of 17 cases. Mutations at codon 130 and at codon 146 were noted in 2 cases. Combined mutations at codon 124, 126, 146 and at 130, 131, 136, 146 were noted in the other 2 cases. Mutations except "a" determinant region included at codon 3, 29, 73, 120, 184, 214, 226, 227. CONCLUSION: These observations suggest that deletion and point mutations in HBV pre-S1, pre- S2 regions and point mutations in HBV S region are frequent in the children with chronic hepatitis B infection.

DEFINITION OF PRE-PRE-S PROMOTER SEQUENCE FROM HEPATITIS B VIRUS GENOME AND IDENTIFICATION OF ITS TRANSCRIPTION ACTIVITY / 解放军医学杂志

To investigate the promoter activity of pre-pre-S gene, which was found in five clones of hepatitis B virus (HBV) genome from 2 patients with chronic HBV infection, promoter DNA sequence was amplified from HBV-DNA by polymerase chain reaction (PCR).The amplified product was cloned into pCAT3 reporter vector. The HepG2 cells were transfected by pCAT3-pre-pre-S-p. The CAT activity was detected by an enzyme-linked immunosorbent assay (ELISA) kit. It was found that pCAT3-pre-pre-S-p had higher activity of CAT which was 10 fold over that of pCAT3-basic. This result implicated that pCAT3-pre-pre-S-p had promoter activity.

Study on gene mutations of single S region in immunoglobulin class switch recombination / 中国免疫学杂志

Objective:To investigate the gene rearrangements in immunoglobulin single switch(S) region during class switch recombination.Methods:An artificial substrate containing single S region(FS?-2) driven by tetracycline-responsive promoter was constructed and underwent CSR in a switch-inducible B lymphoma line was stimulated by cytokines,then the S region mutations and its dependent factors were detected by detected PCR and sequencing.Results:Gene rearrangements including deletions,insertions as well as point mutations could occur even in this single S region after cytokines stimulation;Furthermore,when the upstream promoter was suppressed by its inhibitor,CSR frequency was significantly decreased,indicating a transcription dependent S region recombination.Conclusion:Class switch recombination mechanism can exert a similar effect on single S region.