Rate and durability of the clearance of HBsAg in Alaska Native persons with long-term HBV infection: 1982-2019

BACKGROUND AND AIMS

A functional cure and therapeutic end point of chronic HBV infection is defined as the clearance of HBsAg from serum. Little is known about the long-term durability of HBsAg loss in the Alaskan Native population.

APPROACH AND RESULTS

We performed a retrospective cohort study of Alaska Native patients with chronic HBV-monoinfection from January 1982 through December 2019. The original group in this cohort was identified during a 1982 to 1987 population-based screening for 3 HBV serologic markers in 53,000 Alaska Native persons. With close to 32,000 years of follow-up, we assessed the frequency and duration of HBsAg seroclearance (HBsAg-negative for > 6 mo). We examined factors associated with HBsAg clearance and followed persons for a median of 13.1 years afterward to assess the durability of HBsAg clearance. Among 1079 persons with an average length of follow-up of 33 years, 260 (24%) cleared HBsAg at a constant rate of 0.82% per person/per year. Of the 260 persons who cleared, 249 (96%) remained HBsAg-negative, while 11 persons had ≥ 2 transient HBsAg-positive results in subsequent follow-up.

CONCLUSIONS

Of the patients with chronic HBV monoinfection, 0.82% of people per year achieved a functional cure. HBsAg seroclearance was durable for treated and nontreated patients and lasted, on average, over 13 years without seroreversion.

International circumpolar surveillance: update on the interlaboratory quality control program for Streptococcus pneumoniae, 2009 to 2020

The International Circumpolar Surveillance (ICS) program is a population-based surveillance network for invasive bacterial diseases throughout Arctic countries and territories. The ICS quality control program for Streptococcus pneumoniae serotyping and antimicrobial susceptibility testing has been ongoing since 1999. Current participating laboratories include the Provincial Laboratory for Public Health in Edmonton, Alberta; Laboratoire de santé publique du Québec in Sainte-Anne-de-Bellevue, Québec; the Centers for Disease Control's Arctic Investigations Program in Anchorage, Alaska; the Neisseria and Streptococcus Reference Laboratory at Statens Serum Institut in Copenhagen, Denmark; the Department of Clinical Microbiology, Landspitali in Reykjavik, Iceland; and Public Health Agency of Canada's National Microbiology Laboratory in Winnipeg, Manitoba. From 2009 to 2020, 140 isolates of S. pneumoniae were distributed among the six laboratories as part of the quality control program. Overall serotype concordance was 96.9%, with 99.3% concordance to pool level. All participating laboratories had individual concordance rates >92% for serotype and >97% for pool. Overall concordance by modal minimum inhibitory concentration (MIC) for testing done by broth microdilution or Etest was 99.1%, and >98% for all antimicrobials tested. Categorical concordance was >98% by both CLSI and EUCAST criteria. For two laboratories performing disc diffusion, rates of concordance by modal MIC were >97% for most antimicrobials, except chloramphenicol (>93%) and trimethoprim/sulfamethoxazole (>88%). Data collected from 12 years of the ICS quality control program for S. pneumoniae demonstrate excellent (≥95%) overall concordance for serotype and antimicrobial susceptibility testing results across six laboratories.

IMPORTANCE

Arctic populations experience several social and physical challenges that lead to the increased spread and incidence of invasive diseases. The International Circumpolar Surveillance (ICS) program was developed to monitor five invasive bacterial diseases in Arctic countries and territories. Each ICS organism has a corresponding interlaboratory quality control (QC) program for laboratory-based typing, to ensure the technical precision and accuracy of reference testing services for these regions, and identify and correct potential problems. Here, we describe the results of the ICS Streptococcus pneumoniae QC program, from 2009 to 2020. Excellent overall concordance was achieved for serotype and antimicrobial susceptibility testing results across six laboratories. Ongoing participation in these QC programs ensures the continuation of quality surveillance systems within Arctic populations that experience health disparities.

Streptococcus pneumoniae serotype 3 population structure in the era of conjugate vaccines, 2001-2018

Background. Despite use of highly effective conjugate vaccines, invasive pneumococcal disease (IPD) remains a leading cause of morbidity and mortality and disproportionately affects Indigenous populations. Although included in the 13-valent pneumococcal conjugate vaccine (PCV13), which was introduced in 2010, serotype 3 continues to cause disease among Indigenous communities in the Southwest USA. In the Navajo Nation, serotype 3 IPD incidence increased among adults (3.8/100 000 in 2001-2009 and 6.2/100 000 in 2011-2019); in children the disease persisted although the rates dropped from 5.8/100 000 to 2.3/100 000.Methods. We analysed the genomic epidemiology of serotype 3 isolates collected from 129 adults and 63 children with pneumococcal carriage (n=61) or IPD (n=131) from 2001 to 2018 of the Navajo Nation. Using whole-genome sequencing data, we determined clade membership and assessed changes in serotype 3 population structure over time.Results. The serotype 3 population structure was characterized by three dominant subpopulations: clade II (n=90, 46.9 %) and clade Iα (n=59, 30.7 %), which fall into Clonal Complex (CC) 180, and a non-CC180 clade (n=43, 22.4 %). The proportion of clade II-associated IPD cases increased significantly from 2001 to 2010 to 2011-2018 among adults (23.1-71.8 %; P<0.001) but not in children (27.3-33.3 %; P=0.84). Over the same period, the proportion of clade II-associated carriage increased; this was statistically significant among children (23.3-52.6 %; P=0.04) but not adults (0-50.0 %, P=0.08).Conclusions. In this setting with persistent serotype 3 IPD and carriage, clade II has increased since 2010. Genomic changes may be contributing to the observed trends in serotype 3 carriage and disease over time.

Comparison of HBV DNA and RNA markers in Alaska Native people who did and did not clear hepatitis B surface antigen

In a comparison between 50 Alaska Native persons with chronic hepatitis B who cleared HBV surface antigen (HBsAg) and 50 Alaska Native age-, sex-, and HBV genotype-matched controls, we found differences in changes in HBV DNA and HBV RNA levels over time but no difference in hepatitis B core-related antigen. These findings suggest that serial HBV DNA and HBV RNA may be associated with HBV functional cure defined by HBsAg clearance.

Protection and antibody levels 35 years after primary series with hepatitis B vaccine and response to a booster dose

BACKGROUND AND AIMS

The duration of protection from hepatitis B vaccination in children and adults is not known. In 1981, we used three doses of plasma-derived hepatitis B vaccine to immunize a cohort of 1578 Alaska Native adults and children from 15 Alaska communities who were ≥6 months old.

APPROACH AND RESULTS

We tested persons for antibody to hepatitis B surface antigen (anti-HBs) levels 35 years after receiving the primary series. Those with levels <10 mIU/ml received one booster dose of recombinant hepatitis B vaccine 2-4 weeks later and were then evaluated on the basis of anti-HBs measurements 30 days postbooster. Among the 320 recruited, 112 persons had not participated in the 22- or 30-year follow-up study (group 1), and 208 persons had participated but were not given an HBV booster dose (group 2). Among the 112 persons in group 1 who responded to the original primary series, 53 (47.3%) had an anti-HBs level ≥10 mIU/ml. Among group 1, 73.7% (28 of 38) of persons available for a booster dose responded to it with an anti-HBs level ≥10 mIU/ml at 30 days. Initial anti-HBs level after the primary series was correlated with higher anti-HBs levels at 35 years. Among 8 persons who tested positive for antibody to hepatitis B core antigen, none tested positive for HBsAg or HBV DNA.

CONCLUSIONS

Based on anti-HBs level ≥10 mIU/ml at 35 years and a 73.7% booster dose response, we estimate that 86% of participants had evidence of protection 35 years later. Booster doses are not needed in the general population at this time.

The Alaska Native/American Indian experience of hepatitis C treatment with sofosbuvir-based direct-acting antivirals

BACKGROUND

Direct-acting antiviral (DAA) drugs have been effective in the treatment of chronic hepatitis C virus (HCV) infection. Limited data are available on safety, tolerability, and efficacy in American Indian or Alaska Native people. We aim to evaluate the treatment outcomes of sofosbuvir- based regimens for treatment of HCV in a real life setting in Alaska Native/American Indian (AN/AI) people.

METHODS

AN/AI patients within the Alaska Tribal Health System with confirmed positive anti-HCV and HCV RNA, who were 18 years of age and older were included in the study. Pretreatment baseline patient characteristics, treatment efficacy based on sustained virologic response (SVR) 12 weeks after treatment completion, and adverse effects were assessed. The following treatments were given according to the American Association for the Study of Liver Diseases/Infectious Disease Society of America (AASLD/IDSA) HCV Guidance: ledipasvir/sofosbuvir, sofosbuvir plus weight-based ribavirin, and sofosbuvir/velpatasvir.

RESULTS

We included 501 patients with a mean age of 54.3 (range 21.3-78.3) in the study. Overall SVR was achieved in 95.2% of patients who received one of the three DAA regimens. For those with cirrhosis, overall SVR was 92.8% and for those with genotype 3 91.1% achieved SVR. The most common symptom experienced during treatment was headache. Joint pain was found to decrease during treatment. One person discontinued sofosbuvir plus ribavirin due to myocardial infarction and one discontinued sofosbuvir/velpatasvir due to urticaria.

CONCLUSIONS

In the real-world setting, sofosbuvir-based treatment is safe, effective, and well tolerated in AN/AI patients. Sustained virologic response was high regardless of HCV genotype or cirrhosis status.

Haemophilus influenzae Serotype a (Hia) Carriage in a Small Alaska Community After a Cluster of Invasive Hia Disease, 2018

BACKGROUND

Between May and July 2018, 4 Haemophilus influenzae serotype a (Hia) infections occurred in a remote Alaska community. We performed a public health response to prevent further illness and understand Hia carriage.

METHODS

We collected oropharyngeal samples community-wide to evaluate baseline carriage. Risk factors were evaluated by interview. We offered prophylactic rifampin to individuals in contact with invasive Hia patients (contacts) and to all children aged <10 years. Oropharyngeal samples were collected again 8 weeks after rifampin distribution. Samples were tested using real-time polymerase chain reaction and culture.

RESULTS

At baseline, 4 of 27 (14.8%) contacts and 7 of 364 (1.9%) noncontacts (P < .01) carried Hia. Contacts aged <10 years were more likely to carry Hia at any timepoint (11/18 [61%]) compared to contacts aged ≥10 years (3/34 [8.8%]), noncontacts aged <10 years (2/139 [1.4%]), and noncontacts ≥10 years (6/276 [2.2%]) (P < .001 for all). Hia carriers were clustered in 9 households (7% of total households). At the household level, carriage was associated with households with ≥1 contact (prevalence ratio [PR], 5.6 [95% confidence interval {CI}, 1.3-21.6]), crowding (PR, 7.7 [95% CI, 1.1-199.5]), and ≥3 tobacco users (PR, 5.0 [95% CI, 1.2-19.6]). Elevated carriage prevalence persisted in contacts compared to noncontacts 8 weeks after rifampin distribution (6/25 [24%] contacts, 2/114 [1.8%] noncontacts; P < .001).

CONCLUSIONS

Hia carriage prevalence was significantly higher among contacts than noncontacts. Rifampin prophylaxis did not result in a reduction of Hia carriage prevalence in this community.

Genomic Diversity of Haemophilus influenzae Serotype a in an Outbreak Community, Alaska 2018

BACKGROUND

Haemophilus influenzae serotype a (Hia) can cause severe invasive disease, especially in young children. In 2018, four invasive Hia cases occurred in an Alaska community. We used whole-genome sequencing (WGS) to evaluate the relationship of the bacteria from this community and other Alaska patients with invasive Hia.

METHODS

All carriage (15) and invasive (4) Hia isolates from the outbreak community, together with 15 non-outbreak Alaska invasive Hia surveillance isolates from 2018, were tested for antimicrobial susceptibility and characterized using WGS.

RESULTS

Phylogenetic analysis of both invasive and carriage Hia isolates revealed two major clades that differed by an average of 300 core single nucleotide polymorphisms (SNPs). All isolates from the outbreak community were clustered in one subclade, within a larger clade containing 3 non-outbreak invasive Hia isolates. Comparative genomics did not reveal any genetic mutations that distinguished carriage from invasive isolates. Three (20%) community isolates were rifampin-resistant and had a previously unreported mutation in the rpoB gene.

CONCLUSIONS

In the outbreak community, Hia isolates from carriers were indistinguishable from the invasive Hia isolates. Overall, invasive Hia isolates from Alaska in 2018 were genetically similar. The rifampin resistance mutation is concerning as rifampin is the first-line medication for Hia prophylaxis.

Epidemiology of Invasive Haemophilus influenzae Serotype a Disease-United States, 2008-2017

BACKGROUND

Haemophilus influenzae serotype a (Hia) can cause invasive disease similar to serotype b; no Hia vaccine is available. We describe the epidemiology of invasive Hia disease in the United States overall and specifically in Alaska during 2008-2017.

METHODS

Active population- and laboratory-based surveillance for invasive Hia disease was conducted through Active Bacterial Core surveillance sites and from Alaska statewide invasive bacterial disease surveillance. Sterile-site isolates were serotyped via slide agglutination or real-time polymerase chain reaction. Incidences in cases per 100 000 were calculated.

RESULTS

From 2008 to 2017, an estimated average of 306 invasive Hia disease cases occurred annually in the United States (estimated annual incidence: 0.10); incidence increased by an average of 11.1% annually. Overall, 42.7% of cases were in children aged <5 years (incidence: 0.64), with highest incidence among children aged <1 year (1.60). Case fatality was 7.8% overall and was highest among adults aged ≥65 years (15.1%). Among children aged <5 years, the incidence was 17 times higher among American Indian and Alaska Native (AI/AN) children (8.29) than among children of all other races combined (0.49). In Alaska, incidences among all ages (0.68) and among children aged <1 year (24.73) were nearly 6 and 14 times higher, respectively, than corresponding US incidences. Case fatality in Alaska was 10.2%, and the vast majority (93.9%) of cases occurred among AI/AN.

CONCLUSIONS

Incidence of invasive Hia disease has increased since 2008, with the highest burden among AI/AN children. These data can inform prevention strategies, including Hia vaccine development.

Cascade of Care for Alaska Native People With Chronic Hepatitis C Virus Infection: Statewide Program With High Linkage to Care

Most persons with chronic hepatitis C virus (HCV) infection in the United States are undiagnosed or linked to care. We describe a program for the management of Alaska Native patients infection utilizing a computerized registry and statewide liver clinics resulting in higher linkage to care (86%) than national estimates (~25%).

Observed Changes in Natural Killer and T cell Phenotypes with Evaluation of Immune Outcome in a Longitudinal Cohort Following Sofosbuvir-Based Therapy for Chronic Hepatitis C Infection

Background

Chronic hepatitis C virus (HCV) infection diminishes immune function through cell exhaustion and repertoire alteration. Direct acting antiviral (DAA)-based therapy can restore immune cell subset function and reduce exhaustion states. However, the extent of immune modulation following DAA-based therapy and the role that clinical and demographic factors play remain unknown.

Methods

We examined natural killer (NK) cell, CD4⁺, and CD8⁺ T cell subsets along with activation and exhaustion phenotypes across an observational study of sofosbuvir-based treatment for chronic HCV infection. Additionally, we examined the ability of clinical variables and duration of infection to predict 12 weeks of sustained virologic response (SVR12) immune marker outcomes.

Results

We show that sofosbuvir-based therapy restores NK cell subset distributions and reduces chronic activation by SVR12. Likewise, T cell subsets, including HCV-specific CD8⁺ T cells, show reductions in chronic exhaustion markers by SVR12. Immunosuppressive CD4⁺ regulatory T cells decrease at 4-weeks treatment and SVR12. We observe the magnitude and direction of change in immune marker values from pretreatment to SVR12 varies greatly among participants. Although we observed associations between the estimated date of infection, HCV diagnosis date, and extent of immune marker outcome at SVR12, our regression analyses did not indicate any factors as strong SVR12 outcome predictors.

Conclusion

Our study lends further evidence of immune changes following sofosbuvir-based therapy. Further investigation beyond SVR12 and into factors that may predict posttreatment outcome is warranted.

An Association Between Core Mutations in Hepatitis B Virus Genotype F1b and Hepatocellular Carcinoma in Alaskan Native People

Hepatitis B virus (HBV) genotype F1b infection is strongly associated with hepatocellular carcinoma (HCC) in young Alaskan Native (AN) people. However, the mechanisms by which genotype F1b causes HCC are unclear. Here, we analyzed the clinical and virological significance of genotype F1b in long-term serial samples from 20 HCC patients with HBV infection. Complete sequence analyses revealed that all isolates were genotype F1b. In the HCC patients, T1938C and A2051C mutations in the core region had accumulated significantly with A1762T/G1764A mutations in the basal core promoter (BCP) region and G1896A mutation in the precore (PC) region. Several HBV clones containing the core mutations were examined for their replication efficiency and core stability in vitro. Clones containing the A2051C mutation replicated more efficiently than the wild type in association with enhanced stability of core protein dimerization. In chimeric mice with human hepatocytes carrying BCP/PC/2051 mutant but not with wild-type virus, liver fibrosis was induced in association with high levels of serum HBV DNA and hepatitis B surface antigen. Interestingly, microarray analysis and validation study showed that five genes associated with cell proliferation or carcinogenesis, v-myc avian myelocytomatosis viral oncogene homolog, Grb2-associated binding protein 2, bradykinin receptor B2, follistatin, and mitogen-activated protein kinase kinase kinase 8, were significantly up-regulated in human hepatocytes infected with genotype F1b, particularly the BCP/PC/2051 mutant, compared with other genotypes. Conclusion: We have identified an association between Alaska-specific core mutations and HCC development in AN people infected with genotype F1b; accumulation of these core mutations during the course of chronic infection with genotype F1b would contribute to HCC development in AN people earlier in life.

Tracing hepatitis B virus (HBV) genotype B5 (formerly B6) evolutionary history in the circumpolar Arctic through phylogeographic modelling

Background

Indigenous populations of the circumpolar Arctic are considered to be endemically infected (>2% prevalence) with hepatitis B virus (HBV), with subgenotype B5 (formerly B6) unique to these populations. The distinctive properties of HBV/B5, including high nucleotide diversity yet no significant liver disease, suggest virus adaptation through long-term host-pathogen association.

Methods

To investigate the origin and evolutionary spread of HBV/B5 into the circumpolar Arctic, fifty-seven partial and full genome sequences from Alaska, Canada and Greenland, having known location and sampling dates spanning 40 years, were phylogeographically investigated by Bayesian analysis (BEAST 2) using a reversible-jump-based substitution model and a clock rate estimated at 4.1 × 10⁻⁵ substitutions/site/year.

Results

Following an initial divergence from an Asian viral ancestor approximately 1954 years before present (YBP; 95% highest probability density interval [1188, 2901]), HBV/B5 coalescence occurred almost 1000 years later. Surprisingly, the HBV/B5 ancestor appears to locate first to Greenland in a rapid coastal route progression based on the landscape aware geographic model, with subsequent B5 evolution and spread westward. Bayesian skyline plot analysis demonstrated an HBV/B5 population expansion occurring approximately 400 YBP, coinciding with the disruption of the Neo-Eskimo Thule culture into more heterogeneous and regionally distinct Inuit populations throughout the North American Arctic.

Discussion

HBV/B5 origin and spread appears to occur coincident with the movement of Neo-Eskimo (Inuit) populations within the past 1000 years, further supporting the hypothesis of HBV/host co-expansion, and illustrating the concept of host-pathogen adaptation and balance.

Risk of end-stage liver disease, hepatocellular carcinoma, and liver-related death by fibrosis stage in the hepatitis C Alaska Cohort

Long-term prospective studies of the outcomes associated with hepatitis C virus (HCV) infection are rare and critical for assessing the potential impact of HCV treatment. Using liver biopsy as a starting point, we analyzed the development of end-stage liver disease (ESLD), hepatocellular carcinoma (HCC), and liver-related death (LRD) according to fibrosis stage among a cohort of American Indian/Alaska Native persons in Alaska. Persons were classified as having no/mild (Ishak = 0,1), moderate (Ishak = 2), or severe (Ishak = 3,4) fibrosis or cirrhosis (Ishak = 5,6). We examined time until development of ESLD, HCC, and LRD and report survival probabilities at 3, 5, 7, and 10 years. Of 407 persons, 39% (n = 150) had no/mild fibrosis, 32% (n = 131) had moderate fibrosis, 22% (n = 88) had severe fibrosis, and 9% (n = 38) had cirrhosis. The average time of follow-up was 7.3 years. Within 5 years of biopsy, 1.7% (95% confidence interval [CI]: 0.4-6.8) of persons with no/mild fibrosis developed ESLD compared with 7.9% (95% CI, 4.0-15.2), 16.4% (95% CI, 9.6-27.2), and 49.0% (95% CI, 33.0-67.7) with moderate, severe fibrosis, and cirrhosis, respectively (P < 0.01). The 5-year outcome of HCC was 1.0% (95% CI, 0.1-7.0), 1.0% (95% CI, 0.1-6.6), 1.1% (95% CI, 0.2-7.7), and 13.4% (95% CI, 4.4-36.7) among persons with no/mild fibrosis, moderate fibrosis, severe fibrosis, and cirrhosis, respectively (P < 0.01). Five years after biopsy, 0.0% (95% CI, 0.0-14.8) of persons with no/mild fibrosis had suffered an LRD compared with 1.0% (95% CI, 0.2-7.5) of persons with moderate fibrosis, 4.7% (95% CI, 1.5-14.1) with severe fibrosis, and 16.3% (95% CI, 7.0-35.1) with cirrhosis (P < 0.01).

CONCLUSION

For prevention of HCC, LRD, and ESLD in the short term, HCV therapy should target individuals who have more than mild fibrosis. (Hepatology 2017;66:37-45).

Nested case-control study: hepatocellular carcinoma risk after hepatitis B surface antigen seroclearance

BACKGROUND

Hepatocellular carcinoma (HCC) risk after resolving chronic hepatitis B virus (HBV) infection is unclear.

AIM

To compare HCC risk between Alaska Native (AN) patients with and without hepatitis B surface antigen (HBsAg) seroclearance.

METHODS

We selected persons with (case-patients) and without (control-patients) HBsAg seroclearance from a cohort of 1346 chronically HBV-infected AN patients followed during 1982-2013. We attempted to match two control-patients/case-patient on sex, HBV genotype, and age. Person-years of follow-up for case-patients began on the date of HBsAg resolution and for control-patients began on the date equivalent to the cohort entry date plus the years of HBsAg duration for their corresponding case-patient. We compared HCC risk using a Cox proportional hazards model.

RESULTS

The 238 case-patients (4 with HCC) and 435 control-patients (9 with HCC) were similar in age [P-value (P) = 0.30], sex (P = 0.53) and HBV genotype (P = 0.99). Case-patients had longer person-years of follow-up than control-patients (11.7 vs. 10.1 years; P = 0.04). The HCC rate/100 000 persons was similar between case- (132) and control-patients (178; P = 0.65). The adjusted hazard ratio comparing case- and control-patients was similar for HCC [0.7; 95% confidence interval (CI): 0.2-2.4], increased for each 1-year increment for age (1.1; CI: 1.0-1.1; P < 0.01), and was greater if the initial HBeAg was positive (3.5; CI: 1.1-11.0; P = 0.03).

CONCLUSIONS

Hepatitis B surface antigen seroclearance was not associated with reduced HCC risk; the HCC risk estimates are limited by wide 95% confidence intervals. Persons meeting HCC surveillance indications prior to HBsAg seroclearance could benefit from continued surveillance after seroclearance.

A Longitudinal Hepatitis B Vaccine Cohort Demonstrates Long-lasting Hepatitis B Virus (HBV) Cellular Immunity Despite Loss of Antibody Against HBV Surface Antigen

BACKGROUND

Long-lasting protection resulting from hepatitis B vaccine, despite loss of antibody against hepatitis B virus (HBV) surface antigen (anti-HBs), is undetermined.

METHODS

We recruited persons from a cohort vaccinated with plasma-derived hepatitis B vaccine in 1981 who have been followed periodically since. We performed serological testing for anti-HBs and microRNA-155 and assessed HBV-specific T-cell responses by enzyme-linked immunospot and cytometric bead array. Study subgroups were defined 32 years after vaccination as having an anti-HBs level of either ≥10 mIU/mL (group 1; n = 13) or <10 mIU/mL (group 2; n = 31).

RESULTS

All 44 participants, regardless of anti-HBs level, tested positive for tumor necrosis factor α, interleukin 10, or interleukin 6 production by HBV surface antigen-specific T cells. The frequency of natural killer T cells correlated with the level of anti-HBs (P = .008). The proportion of participants who demonstrated T-cell responses to HBV core antigen varied among the cytokines measured, suggesting some natural exposure to HBV in the study group. No participant had evidence of breakthrough HBV infection.

CONCLUSIONS

Evidence of long-lasting cellular immunity, regardless of anti-HBs level, suggests that protection afforded by primary immunization with plasma-derived hepatitis B vaccine during childhood and adulthood lasts at least 32 years.

Results of interferon-based treatments in Alaska Native and American Indian population with chronic hepatitis C

BACKGROUND

There have been few reports of hepatitis C virus (HCV) treatment results with interferon-based regimens in indigenous populations.

OBJECTIVE

To determine interferon-based treatment outcome among Alaska Native and American Indian (AN/AI) population.

DESIGN

In an outcomes study of 1,379 AN/AI persons with chronic HCV infection from 1995 through 2013, we examined treatment results of 189 persons treated with standard interferon, interferon plus ribavirin, pegylated interferon plus ribavirin and triple therapy with a protease inhibitor. For individuals treated with pegylated interferon and ribavirin, the effect of patient characteristics on response was also examined.

RESULTS

Sustained virologic response (SVR) with standard interferon was 16.7% (3/18) and with standard interferon and ribavirin was 29.7% (11/37). Of 119 persons treated with pegylated interferon and ribavirin, 61 achieved SVR (51.3%), including 10 of 46 with genotype 1 (21.7%), 38 of 51 with genotype 2 (74.5%) and 13 of 22 with genotype 3 (59.1%). By multivariate analysis, SVR in the pegylated interferon group was associated with female sex (p=0.002), estimated duration of infection (p=0.034) and HCV genotype (p<0.0001). There was a high discontinuation rate due to side effects in those treated with pegylated interferon and ribavirin for genotype 1 (52.2%). Seven of 15 genotype 1 patients treated with pegylated interferon, ribavirin and telaprevir or boceprevir achieved SVR (46.7%).

CONCLUSIONS

We had success with pegylated interferon-based treatment of AN/AI people with genotypes 2 and 3. However, there were low SVR and high discontinuation rates for those with genotype 1.

Advancing the high throughput identification of liver fibrosis protein signatures using multiplexed ion mobility spectrometry

Rapid diagnosis of disease states using less invasive, safer, and more clinically acceptable approaches than presently employed is a crucial direction for the field of medicine. While MS-based proteomics approaches have attempted to meet these objectives, challenges such as the enormous dynamic range of protein concentrations in clinically relevant biofluid samples coupled with the need to address human biodiversity have slowed their employment. Herein, we report on the use of a new instrumental platform that addresses these challenges by coupling technical advances in rapid gas phase multiplexed ion mobility spectrometry separations with liquid chromatography and MS to dramatically increase measurement sensitivity and throughput, further enabling future high throughput MS-based clinical applications. An initial application of the liquid chromatography--ion mobility spectrometry-MS platform analyzing blood serum samples from 60 postliver transplant patients with recurrent fibrosis progression and 60 nontransplant patients illustrates its potential utility for disease characterization.

Alaska Native and rural youth views of sexual health: a focus group project on sexually transmitted diseases, HIV/AIDS, and unplanned pregnancy

BACKGROUND

The disparity in rates of sexually transmitted diseases (STDs), HIV/AIDS, and unplanned pregnancy between Alaska Native (AN) and non-AN populations, particularly among young adults and females, is significant and concerning. Focus groups were conducted to better understand the knowledge, attitudes, and beliefs of rural Alaska youth (both AN and non-AN) and communities regarding STDs, HIV/AIDS, and unplanned pregnancy and to determine the best methods to educate and facilitate behavior change in AN youth regarding these issues.

METHODS

A convenience sample of AN and rural youth (n = 105) from 5 communities in Alaska, ages 15-24 years, participated in 21 focus groups. Focus group participants were divided by sex and age. We assessed themes related to knowledge, attitudes, and beliefs about STDs, HIV/AIDS, and unplanned pregnancy, as well as perceptions of how youth prefer to learn about sexual health issues.

RESULTS

The major themes identified were: (1) sexual health is not viewed only in relation to a physical act; (2) there is a basic understanding of sexual health, but youth have a lot of unanswered questions pertaining to STDs and HIV/AIDS; (3) sexual health messages should be delivered via the Internet and school; (4) youth want to hear messages promoting STD/HIV testing and condom use; (5) easier access to condoms is needed; (6) alcohol and drug use affect sexual behavior and risk taking; and (7) issues of confidentiality and embarrassment affect health care-seeking behaviors for sexual health issues.

CONCLUSIONS

One of the fundamental principles of public health practice is community participation, which asserts that success in achieving change is enhanced by the active participation of the intended audience in defining their own high-priority solutions. Our findings-driven by youth themselves-are critical in designing and implementing future sexual health interventions and promoting greater community involvement and acceptance.

Dominant clonotypes within HIV-specific T cell responses are programmed death-1high and CD127low and display reduced variant cross-reactivity

HIV epitope-specific T cell responses are often comprised of clonotypic expansions with distinct functional properties. In HIV(+) individuals, we measured programmed death-1 (PD-1) and IL-7Rα expression, MHC class I tetramer binding, cytokine production, and proliferation profiles of dominant and subdominant TCR clonotypes to evaluate the relationship between the composition of the HIV-specific T cell repertoire and clonotypic phenotype and function. Dominant clonotypes are characterized by higher PD-1 expression and lower C127 expression compared with subdominant clonotypes, and TCR avidity positively correlates with PD-1 expression. At low peptide concentrations, dominant clonotypes fail to survive in culture. In response to stimulation with peptides representing variant epitopes, subdominant clonotypes produce higher relative levels of cytokines and display greater capacity for cross-recognition compared with dominant clonotypes. These data indicate that dominant clonotypes within HIV-specific T cell responses display a phenotype consistent with ongoing exposure to cognate viral epitopes and suggest that cross-reactive, subdominant clonotypes may retain greater capacity to suppress replication of viral variants as well as to survive in the absence of strong antigenic signaling.

Despite biased TRBV gene usage against a dominant HLA B57-restricted epitope, TCR diversity can provide recognition of circulating epitope variants

The role of epitope-specific TCR repertoire diversity in the control of HIV-1 viremia is unknown. Further analysis at the clonotype level is important for understanding the structural aspects of the HIV-1 specific repertoire that directly relate to CTL function and ability to suppress viral replication. In this study, we performed in-depth analysis of T cell clonotypes directed against a dominantly recognized HLA B57-restricted epitope (KAFSPEVIPMF; KF11) and identified common usage of the TCR beta-chain TRBV7 in eight of nine HLA B57 subjects examined, regardless of HLA B57 subtype. Despite this convergent TCR gene usage, structural and functional assays demonstrated no substantial difference in functional or structural avidity between TRBV7 and non-TRBV7 clonotypes and this epitopic peptide. In a subject where TRBV7-usage did not confer cross-reactivity against the dominant autologous sequence variant, another circulating TCR clonotype was able to preferentially recognize the variant peptide. These data demonstrate that despite selective recruitment of TCR for a conserved epitope over the course of chronic HIV-1 infection, TCR repertoire diversity may benefit the host through the ability to recognize circulating epitope variants.

Fluctuations of functionally distinct CD8+ T-cell clonotypes demonstrate flexibility of the HIV-specific TCR repertoire

T-cell receptor (TCR) diversity of virus-specific CD8+ T cells likely helps prevent escape mutations in chronic viral infections. To understand the dynamics of the virus-specific T cells in more detail, we followed the evolution of the TCR repertoire specific for a dominant HLA-B*08-restricted epitope in Nef (FLKEKGGL) in a cohort of subjects infected with HIV. Epitope-specific CD8+ T cells used structurally diverse TCR repertoires, with different TCRbeta variable regions and with high amino acid diversity within antigen recognition sites. In a longitudinal study, distinct Vbeta populations within the HIV-specific TCR repertoire expanded simultaneously with changes in plasma viremia, whereas other Vbeta populations remained stable or even decreased. Despite antigenic variation in some subjects, all subjects had the consensus sequence present during the study period. Functional analysis of distinct Vbeta populations revealed differences in HIV-specific IFN-gamma secretion ex vivo as well as differences in tetramer binding, indicating functional heterogeneity among these populations. This contrasts with findings in a subject on antiretroviral therapy with suppression of viremia to less than 50 copies/mL, where we observed long-term persistence of a single clonotype. Our findings illustrate the flexibility of a heterogeneous HIV-1-specific CD8+ TCR repertoire in subjects with partial control of viremia.

Craig-Scott orthosis: a biochemical and functional evaluation

The Craig-Scott double upright knee ankle orthosis was subjected to a biomechanical evaluation which included analysis of the force interaction with the supported limb and a functional evaluation. The results were compared with data previously determined from biomechanical evaluations of other common orthoses. In the Craig-Scott design, the single application of the knee stabilizing force below the knee concentrates this force in a relatively small bony area, sometimes exceeding tolerance. This might be avoided by using a tibial closure with patellar tendon bearing features. The design was found to produce relatively low anatomic knee shear. In functional aspects such as donning, doffing, transfers and ambulation, the orthosis is essentially equivalent to other double upright designs. The rigidity of the orthosis with only a tibial band closure and a bail connecting the uprights was determined to be adequate. The limited number of bands and closures provides some advantages in reduced donning and doffing time; however, in the absence of posterior closures below the knee, the orthosis had a tendency to slide forward off the leg when transferring. This disadvantage was eliminated by adding a soft posterior closure below the knee, which produced a minimal increase in donning and doffing times.