The Effect Of Highly Active Antiretroviral Therapy(HARRT) On The Prevalence Of HBV Drug Resistance Mutations In HIV/HBV Co-infected Patients

Object:Since HIV/AIDS patients were treated with highly active antiretroviral therapy（HAART）,their condition has been controlled and improved.However,some of anti-HIV drugs are also active against hepatitis B virus（HBV）.Long-term management result in highler rate of HBV resistance mutation in HIV/HBV co-infected patients.This is especially problematic when the HBV status is not known prior to treatment of HIV.Guangxi is one of the provinces in China with the highest prevalence of HIV/HBV co-infection.However,the prevalence of HBV drug resistance mutations in HBV/HIV co-infected patients between those on HAART and untreated patients remains unclear.In this study,we aimed to address these issues.Methods:Blood samples and clinic data were collected from HIV/HBV co-infected patients including 123 drug na?ve subjects（group 1）and 80 subjects on HAART（group 2）.The polymerase gene of HBV in serum of all study subjects was amplified by PCR and sequenced.Sequence obtained were analysed.Neighbour-joining trees were reconstructed based on S gene sequences.Univariate and multivariate logistic regression analysis were carried out to search for factors associated with the development of drug resistance mutations.Results:1.Characteristics of the study subjects.HBV DNA was successfully amplified and sequenced from 86 subjects,including 69（Group 1）who were drug na?ve and 17（Group 2）who had received highly active antiretroviral therapy（HARRT）.The PCR positive rates for Group 1 and 2 were 56.1%（95%CI:47.3-64.9）and 21.3（95%CI:12.3-30.3）,respectively.The mean ages in Group 1 and 2 were 43.6±1.2 and 37.2±7.3 years,respectively.2.The prevalence of drug resistance.Overall,the prevalence of amino acid substitutions in the RT region was 50%（95%CI:39.4-60.6）.The prevalences in Group 1 and 2 were 39.1%（95%CI:27.6-50.6）and 94.1%（95%CI:82.9-105.3）,respectively.The difference in the rates between the two groups is significant（χ²=16.496,p<0.05）.The total prevalence of HBV drug resistance mutations was 16.3%（95%CI:8.5-24.1）.The rates in Group 1 and 2 were 1.4%（95%CI:-1.4-4.2）and 76.5%（95%CI:56.3-96.7）,respectively.The difference in the rates between the two groups is significant（χ²=50.955,p<0.05）.3.The pattern of drug resistance mutations.The most common substitution in the RT region leading to drug resistance is L180M,which was detected in 85.7%（95%CI:67.4-104.0）subjects.The major pattern of3TC-resistance mutations is L180M+M204I+L80I,which was observed in35.7%（13/14,95%CI:10.6-60.8）of the subjects.The major pattern of entecavir-resistance mutations is M204V+L180M,which was observed in71.4%（10/14,95%CI:47.7-95.1）of the subjects.The major pattern of telbivudine-resistance mutations is M204I,L80I（42.9%,6/14,95%CI:17.0-68.8）.Of the 14 patients,100%had HBV cross-resistance to telbivudine and entecavir.No putative TDF resistance change was detected in the subjects undergoing treatment with 3TC plus TDF.4.The prevalence of drug resistance mutations according to genotype.Three HBV genotypes were identified in this study,including genotypes B,C（subgenotypes C₂ and C₅）and I.They account for 57.0%（95%CI:46.5-67.5）,20.9%（95%CI:12.3-29.5）,17.4%（95%CI:9.4-25.4）and 4.7%（95%CI:0.2-9.2）,respectively.The prevalence of drug resistance mutatinsis significantly higher in genotype C（11/33,33.3%,95%CI:17.2-49.4）than in genotype B（6.1%,3/49,95%CI:-0.60-12.80）（χ²=10.312,p<0.05）.5.The prevalence of drug resistance mutations according to CD4counts.Among 83 subjects for whom CD4 cell counts were determined,the median（range）of CD4 cell count was 219 IU/mm³,ranging from 2 to 990 IU/mm³.The prevalence of drug resistance mutations is significantly higher in those with CD4 cell counts>500 IU/mm³ than in those with CD4 counts<500IU/mm³（χ²=13.333,p<0.05）.6.The prevalence of drug resistance mutations according HBeAg status.The positive rate of HBe Ag was significantly higher in Group 2（92.9%,95%CI:79.4-106.4）than Group 1（42.6%,95%CI:30.8-54.4）（χ²=10.082,p<0.05）.The prevalence of drug resistance mutations is significantly higher in HBeAg positive subjects（26.2%）than in HBeAg negative subjects（2.5%）（χ²=10.439,p<0.05）.7.The effect of HAART on HIV and HBV replication.Five subjects（6.25%,5/80,95%CI:0.95-11.55）had HBV viral loads over 10×10⁶ copies/ml;One of them has been treated with a regimen including tenofovir disoproxil fumarate for four years.Four of these 5 patients had 3TC-resistance and three of the four had received antiviral treatment for at least 6.5 years.The HBV viral loads of most subjects who received HAART were below the lowest limit of detection（<30 copies/ml）（73/80,91.2%,95%CI:85.1-97.4）.8.Factors associated with drug resistance mutations.Multivariable logistic regression analysis was performed to identif-y factors that affect the prevalence of drug resistance mutations.Gender,genotype,CD4 count,HBeAg/anti-HBe and HAART,but not age,were found to be associated with the development of drug resistance mutations on univariate analysis.However,only HAART was found to be associated with the development of drug resistance mutations on multivariate analysis（p=0.0001,OR=195.757,95%CI:14.135-2711）.Conclusion:Treating HIV in HIV/HBV co-infection patients may increase the prevalence of HBV drug resistance mutations.There is cross-resistance to antiviral agents and attention should be paid when new durg is used as rescue therapy.TDF could not completely suppress HBV replication.The effect of using TDF as rescue therapy for 3TC resistance in HIV/HBV co-infected patients is limited.