Pope Kosalaraksa

HIV-1 acquires resistance to two classes of antiviral drugs through homologous recombination

Genetic recombination contributes to the genomic heterogeneity of human immunodeficiency virus type 1 (HIV-1). In the present study, we demonstrate that HIV-1 readily develops resistance to two classes of anti-HIV-1 drugs through in vitro genetic recombination involving large segments of the viral genome. Co-transfection of COS-7 cells with an HIV-1 plasmid (pSUM13) carrying five mutations in the reverse transcriptase (RT)-encoding region (A62V, V75I, F77L, F116Y, Q151M), conferring resistance to multiple dideoxynucleoside analogs (ddNs), and another HIV-1 plasmid (pSUM431) carrying five mutations in the protease-encoding region (V321, L33F, K451, 184V, L89M), conferring resistance to protease inhibitors such as KNI-272, readily produced HIV-1 carrying both sets of mutations when propagated in MT-2 cells in the presence of azidothymidine (AZT) and KNI-272. The resultant HIV-1 variant was highly resistant to both ddNs and KNI-272. Co-infection of MT-2 cells with HIV-1SUM13 carrying the RT mutations and HIV-1SUM431 carrying the mutations in the protease also generated HIV-1 with both sets of mutations when cultured with AZT and KNI-272. We also report here that the problematic artifactual recombination occurring during genetic analyses of heterogeneous nucleic acid sequences using polymerase chain reaction can be successfully obviated.

Pathways for the emergence of multi-dideoxynucleoside-resistant HIV-1 variants.

Objective: To investigate the mechanism by which the Q151M mutation in reverse transcriptase (RT) that confers multi-dideoxynucleoside resistance on HIV-1 and that requires a two base change (CAG←ATG) develops, and to understand the reason for the relatively lengthy period of time required for its emergence under therapy with multiple nucleoside RT inhibitors (NRTI). Design and methods: Propagation assays and competitive HIV-1 replication assays were used to evaluate the fitness of various infectious clones, including two putative intermediates (HIV-1Q151K(AAG) and HIV-1Q151L(CTG)) for HIV-1Q151M(ATG), in terms of sensitivity to zidovudine and didanosine. Steady-state kinetic constants of recombinant RT were also determined. Results: HIV-1Q151L replicated relatively poorly while HIV-1Q151K failed to replicate. When HIV-1Q151L was propagated further, it took three pathways in continuing to replicate: (i) HIV-1Q151L changed to HIV-1Q151M in eight of 16 experiments; (ii) HIV-1Q151L reverted to wild-type HIV-1 (HIV-1WT) in four of 16 experiments; and (iii) HIV-1Q151L acquired an additional mutation M230I in four of 16 experiments improving HIV-1 fitness. The relative order of replicative fitness without drugs was: HIV-1Q151M > HIV-1WT > HIV-1Q151L/M230I > HIV-1M230I >> HIV-1Q151L >>> HIV-1Q151K, HIV-1Q151K/M230I. HIV-1Q151M was less susceptible to drugs, while HIV-1Q151L/M230I was as sensitive as HIV-1WT. Enzymatic assays corroborated that HIV-1Q151L is more replication-competent than HIV-1WT and HIV-1Q151K in the presence of drugs. Conclusion: HIV-1Q151M probably develops through a poorly replicating HIV-1Q151L; however, it is also possible that it occurs through two concurrent base changes. The present data should explain the mechanism by which HIV-1Q151M emerges after long-term chemotherapy with NRTI.

An open-label, randomized study of a 9-valent human papillomavirus vaccine given concomitantly with diphtheria, tetanus, pertussis and poliomyelitis vaccines to healthy adolescents 11-15 years of age.

Background: A 9-valent human papillomavirus (9vHPV) vaccine has recently been reported to be safe and highly efficacious against infection and disease related to HPV6/11/16/18/31/33/45/52/58. We evaluated the immunogenicity and safety of the 9vHPV vaccine administered concomitantly with REPEVAX (diphtheria, tetanus, acellular pertussis and inactivated poliomyelitis vaccine). Methods: This open-label, randomized, multicenter study enrolled 1054 males and females ages 11–15 years. Subjects were randomly assigned to each group in a 1:1 ratio. Subjects received a 0.5 mL dose of 9vHPV vaccine intramuscularly at day 1, months 2 and 6 and a 0.5 mL dose of REPEVAX either on day 1 (concomitant vaccination group; n = 526) or at month 1 (nonconcomitant vaccination group, n = 528). Serologic responses for each vaccine component were tested by 1-sided tests of noninferiority between groups. Systemic and injection-site adverse experiences (AEs) and serious AEs were monitored. Results: Noninferiority of anti-HPV geometric mean titers and seroconversion rates for all 9vHPV antigens were demonstrated for the concomitant group compared with the nonconcomitant group. Seroconversion rates for the 9vHPV vaccine types were ≥99.8% in both groups at month 7. For REPEVAX, noninferiority of immune response was established for diphtheria, tetanus, all polio and pertussis antigens for both groups. There were no vaccine-related serious AEs. Conclusion: Overall, concomitant administration of 9vHPV vaccine and REPEVAX was generally well tolerated and did not interfere with the immune response to either vaccine. This strategy would minimize the number of visits required to deliver each vaccine individually.

Primary immunization of infants and toddlers in Thailand with Japanese encephalitis chimeric virus vaccine in comparison with SA14-14-2: a randomized study of immunogenicity and safety.

Background: The live, attenuated Japanese encephalitis (JE) chimeric virus vaccine (JE-CV) is licensed in Thailand and Australia for prophylaxis of JE in individuals at the age of 12 months. JE-CV has not yet been compared with the SA14-14-2 JE vaccine, which is also licensed in Thailand. Methods: In this phase 3, observer-blinded trial, 300 children at the age of 9–18 months were randomized 1:1 to receive 1 dose of JE-CV or SA14-14-2. JE neutralizing antibody titers were assessed using PRNT50. The primary endpoint was the noninferiority of seroconversion against JE on Day 28 after JE-CV compared with SA14-14-2, as assessed using the 95% confidence interval of the difference between the groups. Safety and reactogenicity were described in each group using conventional methods, including the reporting of solicited and unsolicited adverse events. Results: The seroconversion rate on Day 28 was 99.2% in each group. Noninferiority was demonstrated as the difference between the JE-CV and SA14-14-2 groups was −0.012 percentage points (95% confidence interval: −3.6 to 3.6), which was above the required −10%. The seroprotection rate remained very high at Month 6 and comparable between groups, but a slight decrease was observed in the JE-CV group between Months 6 and 12. Current recommendations for both vaccines call for a booster dose 12–24 months after primary immunization to maintain high seroprotection rates in the long term. Geometric mean titers (GMTs) on Day 28 after vaccination were 507 (1/dil) in the JE-CV group and 370 (1/dil) in the SA14-14-2 group, decreasing by 4.3-fold and 3.6-fold, respectively, to Month 6 before remaining stable to Month 12 and comparable between groups. Solicited reactions were all reported at lower rates after vaccination with JE-CV compared with SA14-14-2. Conclusions: A single dose of JE-CV elicited a noninferior immune response compared with SA14-14-2 and had a satisfactory safety profile.

Impact of Antiretroviral Therapy on Quality of Life in HIV-Infected Southeast Asian Children in the PREDICT Study

Quality of life (QOL) is an important antiretroviral treatment (ART) outcome. We compared QOL among 299 Thai and Cambodian children ages 1-12 years-old, CD4 15-24% randomized to early (ART at week 0, N=149) versus deferred groups (ART when at CD4 <15%, N=150) and also compared with QOL data from age-matched healthy controls (N=275). Primary caregivers completed PACTG QOL questionnaires at week 0 and every 24 weeks until 144 weeks. Children were enrolled during March 2006 to September 2008. Mean (SD) age of children was 6.3 (2.8) years, 58% were female, 60% were Thai, %CDC N:A:B:C was 2:62:36:0%. During 144 weeks, all children in the early-group and 69 (46%) of deferred-group children started ART. There was no significant difference of QOL scores between treatment groups at baseline (all p>0.05) and at week 144 (all p>0.05). By multivariate analysis, the early-group had higher QOL score changes in five domains, including health perception (p=0.04), physical resilience (p=0.02), psychosocial well-being (p=0.04), social and role functioning (p<0.01), and symptoms (p=0.01) compared to the deferred group. QOL of HIV-infected children in both groups were lower than healthy control in all 7 domains at baseline (all p<0.05) and 5 of 7 domains at weeks 144 (p<0.01). In conclusion, no significant difference of QOL scores between treatment groups. Early ART commencement associated with greater increase of QOL scores over 144 weeks. QOL scores in HIV-infected children were lower than healthy controls.

Prevalence of Human Leukocyte Antigen-B*5701 Among HIV-infected Children in Thailand and Cambodia: Implications for Abacavir Use

Human leukocyte antigen (HLA)-B*5701 allele is associated with abacavir hypersensitivity. Limited data among Asians showed lower rates of HLA-B*5701 compared with Caucasians. In 296 children with HIV in Thailand and Cambodia, the prevalence of HLA-B*5701 was 4.0% (95% confidence interval: 1.6–8.0%) among Thai and 3.4% (95% confidence interval: 0.9–8.5%) among Cambodian children. HLA-B*5701 carriage is not uncommon among Thai and Cambodian children; it is close to the prevalence found in European and higher than the prevalence found in East Asian and African studies.

Monoboosted lopinavir/ritonavir as simplified second-line maintenance therapy in virologically suppressed children.

Background:Monoboosted protease inhibitor is being evaluated as a strategy to simplify therapy in virologically suppressed patients who are on complex regimens. Methods:Children with two consecutive HIV-RNA below 50 copies/ml at least 3 months apart while on double boosted protease inhibitor (dPI) were switched to monoboosted lopinavir/r (mLPV/r). The previous dPI regimen was resumed within 4 weeks in children who experienced virological failure defined as two HIV-RNA at least 500 or three HIV-RNA at least 50 copies/ml. Primary endpoint was the proportion of children still on mLPV/r and having HIV-RNA less than 50 copies/ml at week 48. Results:Forty children on LPV/r + saquinavir (90%) or LPV/r + indinavir (10%) were enrolled, 50% were female, median [interquartile range (IQR)] age was 11.7 (10.2–13.5) years, and body weight was 29.4 (24.1–40.2 kg). The median (IQR) CD4% was 27 (23.5–29.5%). At 48 weeks, none had died or had HIV disease progression. Thirty-one children were on mLPV/r and 29 (72.5%) had HIV-RNA less than 50 copies/ml. Nine resumed dPI due to mLPV/r failure with four achieving undetectable HIV-RNA. Overall, 31 children (82.5%) had HIV-RNA suppression. Predicting factor for failing mLPV/r was baseline HIV-RNA at least 50 copies/ml. No major protease mutations were found. Conclusion:By simplifying second-line treatment from dPI to mLPV/r, the majority of children had sustained viral suppression at 48 weeks. Randomized study of simplified mono protease inhibitor therapy in children is warranted.

Long-Term Immunogenicity of a Single Dose of Japanese Encephalitis Chimeric Virus Vaccine in Toddlers and Booster Response 5 Years After Primary Immunization.

Background: Japanese encephalitis (JE) is an important mosquito-borne viral disease that is endemic in Asia, Western Pacific countries and Northern Australia. Although there is no antiviral treatment, vaccination is effective in preventing this disease. Methods: We followed a cohort of 596 children for 5 years after primary vaccination at 12–18 months of age with JE chimeric virus vaccine (JE-CV; IMOJEV) in a multicenter, phase III trial in Thailand and the Philippines to assess antibody persistence and safety. At the end of the 5 years, a subgroup of 85 participants, at 1 site in Thailand, was followed after administration of a JE-CV booster vaccination. JE antibody titers were measured annually after primary vaccination and 28 days after booster vaccination using a 50% plaque reduction neutralization test. Seroprotection was defined as a JE-CV neutralizing antibody titer ≥10 (1/dil). Kaplan–Meier survival analysis was used to estimate the proportion of participants maintaining protective JE-CV neutralizing antibody titers. Results: At 1, 2, 3, 4 and 5 years after vaccination with JE-CV, 88.5%, 82.9%, 78.2%, 74.0% and 68.6% of the participants followed remained seroprotected. Geometric mean titers in the subgroup assessed after receipt of a booster dose increased from 61.2 (95% confidence interval: 43.8–85.7) pre-booster to 4951 (95% confidence interval: 3928–6241) 28 days post-booster, with all participants seroprotected. There were no safety concerns identified. Conclusions: Protective immune responses persisted for at least 5 years after a JE-CV primary immunization in the majority of participants. JE-CV booster induced a robust immune response even after a 5-year interval.

Persistence of hepatitis B immune memory until 9–10 years of age following hepatitis B vaccination at birth and DTaP-IPV-HB-PRP∼T vaccination at 2, 4 and 6 months

ABSTRACT Objective: To evaluate the long-term persistence of anti-hepatitis B surface (HBs) antibodies and the response to a HB challenge re-vaccination in children who had received a primary series of DTaP-IPV-HB-PRP∼T (Hexaxim™) or DTaP-IPV-HB/PRP∼T (Infanrix hexa™). Methods: Two cohorts of participants who had previously received HB vaccine at birth followed by either DTaP-IPV-HB-PRP∼T or DTaP-IPV-HB/PRP∼T co-administered with PCV7 at 2, 4, 6 months of age in a randomized, Phase III, observer-blind study in Thailand, were followed up for anti-HBs antibodies (geometric mean concentrations [GMCs] and seroprotection [SP] rate [% of participants with a titer ≥10 mIU/mL]) at 12–18 months of age and 9–10 years of age. A monovalent HB challenge re-vaccination was administered at 9–10 years of age and the anamnestic response was evaluated. Results: Anti-HBs GMCs and SP rates in the DTaP-IPV-HB-PRP∼T and DTaP-IPV-HB/PRP∼T groups were high and similar post-primary vaccination series (2477 mIU/mL and 99.5% and 2442 mIU/mL and 99.5%, respectively) and declined to a similar extent in each group at 12–18 months (154.5 mIU/mL and 90.8% and 162.3 mIU/mL and 96.5%, respectively). Antibody levels further declined at 9–10 years of age (13.3 mIU/mL and 49.3% and 8.0 mIU/mL and 42.9%) and a strong anamnestic response occurred in each group post-HB challenge re-vaccination (92.8% and 98.7%, respectively). Conclusion: The kinetics of long-term anti-HBs antibody persistence were similar following a primary series of DTaP-IPV-HB-PRP∼T or DTaP-IPV-HB/PRP∼T. The response to a subsequent HB challenge re-vaccination was strong and similar in each group, demonstrating persisting immune memory.

Reactogenicity and safety of AS03B-adjuvanted H5N1 influenza vaccine in children: an open-label, one-way, crossover trial

Abstract Background Human cases of highly pathogenic avian-origin influenza A/H5N1 infection continue to be reported to the World Health Organization, and recent outbreaks of human cases of other zoonotic influenza strains highlight the continued need for strategies to mitigate influenza pandemic potential. Methods A Phase II–III randomized, placebo-controlled, observer-blind trial was conducted to assess the immunogenicity, reactogenicity, and safety of two 1.9 μg hemagglutinin doses of AS03B-adjuvanted H5N1 (AS03B-H5N1; A/Indonesia) vaccine in children (6 months to <18 years old) of Thailand, the United States, and Canada (Year 1, published elsewhere). After database lock in Year 1, the trial was unblinded, and children who had been randomized to receive placebo and continued to fulfill the eligibility criteria were invited to participate in an open-label, one-way, crossover safety extension phase, in which they received AS03B-H5N1 vaccine. Here we report the safety analysis in Year 2. Results A total of 155 children were vaccinated in Year 2. The most frequent solicited adverse event (AE) during 7 days post vaccination was injection site pain. Irritability or fussiness was reported in about one-third of younger children (aged <6 years) during 7 days post vaccination and was the most common solicited general AE in this age group. Postvaccination temperature (≥38°C) was reported in 4 (5.1%) children. The most common solicited general AEs in older children (aged ≥6 years) were muscle aches, headache, and fatigue. The AS03B-H5N1 vaccine had a clinically acceptable safety profile up to 385 days post vaccination. Conclusions Safety in the crossover phase was acceptable and consistent with that observed in vaccine recipients in the randomized, blinded phase of the study. Clinical trial registration ClinicalTrials.gov: NCT01310413.