Hepatitis B seroconversion revisited: new insights into the natural history of acute hepatitis B virus (HBV) infection from quantitative and highly sensitive assays and novel biomarkers.

BACKGROUND: Hepatitis B virus (HBV) serum markers during typical acute self-limited infection are usually depicted as a composite of traditional HBV markers. The current study updates and expands our knowledge of acute hepatitis B with quantitative molecular and serological data on longitudinal samples from five plasmapheresis donors with acute HBV. METHODS: 137 longitudinal samples from five plasmapheresis donors with acute HBV were tested, four with self-limited infection and one who developed persistent infection. Testing included quantitative hepatitis B surface antigen (HBsAg), antibodies to HBV antigens, quantitative HBV e antigen (HBeAg), HBV DNA, quantitative HBV core-related antigen (HBcrAg), the highly sensitive ARCHITECT HBsAg NEXT (HBsAgNx) assay, and a quantitative research assay for HBV pregenomic RNA (pg RNA). RESULTS: Peak levels of HBV DNA and HBsAg differed by several orders of magnitude among the panels (2.2 × 105-2.7 × 109 IU/ml for HBV DNA and 7.9-1.1 × 105 IU/ml for HBsAg). HBsAg levels peaked an average of 2.8 days after the HBV DNA peak. The overall duration of observed HBsAg positivity was increased by the more sensitive HBsAgNx assay compared to the quantitative assay in four panels. Intermittently detectable low-level HBV DNA was observed after HBsAg loss in three panels. Peak HBeAg levels occurred 2-20 days after the DNA peak and ranged from 1.1 to 4.5 × 103 IU/ml. In four panels with resolution of infection, anti-HBs levels indicating immunity (≥ 10 mIU/ml) were detected 19-317 days after the HBV DNA peak. Maximum HBcrAg concentrations ranged from 1 × 105 to > 6.4 × 106 U/ml and correlated with HBeAg values (R2 = 0.9495) and with HBV DNA values (R2 = 0.8828). Peak pgRNA values ranged from 1.6 × 103 to 1.4 × 108 U/ml and correlated with HBV DNA (R2 = 0.9013). CONCLUSION: Traditional and new/novel HBV biomarkers were used to generate molecular and serological profiles for seroconversion panels spanning the early to late phases of acute HBV. Seroconversion profiles were heterogeneous and may be instructive in appreciating the spectrum of acute profiles relative to the typical composite representation.

Early emergence of anti-HCV antibody implicates donor origin in recipients of an HCV-infected organ.

Hepatitis C virus (HCV) seroconversion among HCV-uninfected transplant recipients from HCV-infected (NAT+/Antibody+) or HCV-exposed (NAT-/Antibody+) donors has been reported. However, the origin of anti-HCV antibody and the implications of seroconversion remain unknown. We longitudinally tested plasma from HCV-uninfected kidney (n = 31) or heart transplant recipients (n = 9) of an HCV NAT+ organ for anti-HCV antibody (both IgG and IgM isotypes). Almost half of all participants had detectable anti-HCV antibody at any point during follow-up. The majority of antibody-positive individuals became positive within 1-3 days of transplantation, and 6 recipients had detectable antibody on the first day posttransplant. Notably, all anti-HCV antibody was IgG, even in samples collected posttransplant day 1. Late seroconversion was uncommon (≈20%-25% of antibody+ recipients). Early antibody persisted over 30 days in kidney recipients, whereas early antibody dropped below detection in 50% of heart recipients within 2 weeks after transplant. Anti-HCV antibody is common in HCV-uninfected recipients of an HCV NAT+ organ. The IgG isotype of this antibody and the kinetics of its appearance and durability suggest that anti-HCV antibody is donor derived and is likely produced by a cellular source. Our data suggest that transfer of donor humoral immunity to a recipient may be much more common than previously appreciated.

Hepatitis C virus surveillance and identification of human pegivirus 2 in a large Cameroonian cohort.

The prevalence of chronic hepatitis C virus (HCV) and the presence of human pegivirus 2 (HPgV-2) have not been examined in Cameroon, although HCV has been associated with HPgV-2 infections previously. Herein we aimed to characterize the burden and genetic diversity of HCV and the presence of HPgV-2 in Cameroon. Retrospective plasma specimens collected from N = 12 369 consenting subjects in South Cameroon from 2013 to 2016 were included in the study. The majority (97.1%) of participants were patients seeking health care. All specimens were screened for HCV using the Abbott RealTime HCV viral load assay and positive specimens with remaining volume were also screened for HPgV-2 antibodies on the Abbott ARCHITECT instrument, followed by molecular characterization. Overall, HCV RNA was detected in 305 (2.47%; 95% CI: 2.21%-2.75%) specimens. Notably, the prevalence of HCV RNA was 9.09% amongst participants over age 40 and 3.81% amongst males. Phylogenetic classification of N = 103 HCV sequences identified genotypes 1 (19.4%), 2 (15.5%) and 4 (65.1%) within the study cohort. Amongst HCV RNA-positive specimens, N = 28 (10.6%; 95% CI: 7.44%-14.90%) specimens also had detectable HPgV-2 antibodies. Of these, N = 2 viremic HPgV-2 infections were confirmed by sequencing and shared 93-94 median % identity with strains found on other continents. This is the first study to determine the prevalence of chronic HCV in Cameroon, and the discovery of HPgV-2 in this study cohort expands the geography of HPgV-2 to the African continent, indicating a widespread distribution exists.

Identification of hepatitis B virus genotype I in Thailand.

The rare hepatitis B virus genotype I (HBV-I) classification includes complex A/G/C/U recombinants identified amongst the individuals from China, India, Laos, and Vietnam. Herein we report the first HBV-I specimen from Thailand, with detectable HBsAg despite a 10-amino-acid truncation. This HBV-I genome has a similar recombinant pattern to reference strains, including a C region that branches basal to references, suggesting a premodern era recombination event gave rise to HBV-I. With an average sequence divergence from other genotypes ranging from 7.66% (standard deviation [SD], 0.42%; C) to 14.27% (SD, 0.31%; H), this new genome supports the HBV-I classification as a unique genotype.

Hepatitis B Virus Serum DNA andRNA Levels in Nucleos(t)ide Analog-Treated or Untreated Patients During Chronic and Acute Infection.

Treatment of chronic hepatitis B (CHB) patients with nucleos(t)ide analogs (NAs) suppresses hepatitis B virus (HBV) DNA synthesis but does not affect synthesis of HBV pregenomic RNA (pgRNA). Hepatitis B virus pgRNA is detectable in the serum during NA treatment and has been proposed as a marker of HBV covalently closed circular DNA activity within the infected hepatocyte. We developed an automated assay for the quantification of serum HBV pgRNA using a dual-target real-time quantitative PCR approach on the Abbott m2000sp/rt system. We demonstrate accurate detection and quantification of serum HBV RNA. Hepatitis B virus DNA was quantified using the Abbott RealTime HBV viral load assay. We further compared serum nucleic acid levels and kinetics in HBV-positive populations. Samples included on-therapy CHB samples (n = 16), samples (n = 89) from 10 treatment naïve CHB subjects receiving 12 weeks of NA treatment with 8-week follow-up, hepatitis B surface antigen-positive blood donor samples (n = 102), and three seroconversion series from plasmapheresis donors (n = 79 samples). Conclusion: During NA treatment of CHB subjects, we observed low correlation of HBV DNA to pgRNA levels; pgRNA concentration was generally higher than HBV DNA concentrations. In contrast, when NA treatment was absent we observed serum pgRNA at concentrations that correlated to HBV DNA and were approximately 2 log lower than HBV DNA. Importantly, we observe this trend in untreated subject samples from both chronic infections and throughout seroconversion during acute infection. Results demonstrate that the presence of pgRNA in serum is part of the HBV lifecycle; constant relative detection of pgRNA and HBV DNA in the serum is suggestive of a linked mechanism for egress for HBV DNA or pgRNA containing virions.

Molecular and serological characterization of hepatitis B vaccine breakthrough infections in serial samples from two plasma donors.

BACKGROUND: Although vaccines for hepatitis B virus (HBV) are highly effective, HBV infections in vaccinees occur. Index samples of breakthrough infections are typically anti-HBc negative but HBV DNA positive with protective anti-HBs levels while HBsAg detection may be delayed or absent. HBsAg mutations have been associated with some vaccine breakthrough cases. METHODS: This research characterizes the serological and molecular profiles of vaccine breakthrough infections in serial samples from two commercially available plasma donor panels. Samples were tested with commercially available assays for HBV antigens and antibodies: HBsAg, HBeAg, anti-HBc, anti-HBc IgM, anti-HBe, and anti-HBs. Different immunoassay approaches for earlier detection of breakthrough infection were explored including hepatitis B core-related antigen (HBcrAg), a research assay for preS2 antigen, and a new prototype ARCHITECT HBsAg assay with improved sensitivity. The prototype HBsAg assay is fully automated and involves no sample pre-treatment. Molecular testing included HBV DNA quantitation and sequencing of preS1, preS2, surface, and basal core promoter/core promoter genes. RESULTS: Although the research preS2 antigen assay allowed earlier detection of the breakthrough infections than current HBsAg assays and HBcrAg, the new prototype ARCHITECT HBsAg assay provided the earliest serologic detection. The ability of the new prototype HBsAg assay to detect HBsAg in the presence of anti-HBs was investigated using known concentrations of native HBsAg mixed with anti-HBs from a vaccinee. The results demonstrated that the prototype ARCHITECT assay is more sensitive in detecting HBsAg in the presence of anti-HBs than current HBsAg assays. Sequencing revealed multiple substitutions in preS1, preS2, and S regions for one panel including a rare D144N substitution associated with vaccine breakthrough that emerged with increasing frequency as the breakthrough infection developed. CONCLUSIONS: When compared with other immunoassay approaches, the new prototype ARCHITECT HBsAg assay allows earlier detection of vaccine breakthrough infections and more sensitive detection of HBsAg in the presence of anti-HBs. Molecular characterization of longitudinal samples demonstrated the progressive appearance of a rare HBsAg mutation associated with vaccine breakthrough.

An Efficient, Large-Scale Survey of Hepatitis C Viremia in the Democratic Republic of the Congo Using Dried Blood Spots.

Background: Efficient viral load testing is needed for hepatitis C (HCV) surveillance and diagnosis. HCV viral load testing using dried blood spots (DBSs), made with a single drop of finger-prick whole blood on filter paper, is a promising alternative to traditional serum- or plasma-based approaches. Methods: We adapted the Abbott Molecular m2000 instrument for high-throughput HCV viremia testing using DBSs with simple specimen processing and applied these methods to estimate the national burden of infection in the Democratic Republic of the Congo (DRC). We tested DBSs collected during the 2013-2014 DRC Demographic and Health Survey, including 1309 adults ≥40 years of age. HCV-positive samples underwent targeted sequencing, genotyping, and phylogenetic analyses. Results: This high-throughput screening approach reliably identified HCV RNA extracted from DBSs prepared using whole blood, with a 95% limit of detection of 1196 (95% confidence interval [CI], 866-2280) IU/mL for individual 6-mm punches and 494 (95% CI, 372-1228) IU/mL for larger 12-mm punches. Fifteen infections were identified among samples from the DRC Demographic and Health Survey; the weighted country-wide prevalence of HCV viremia was 0.9% (95% CI, 0.3%-1.6%) among adults ≥40 years of age and 0.7% (95% CI, .6%-.8%) among human immunodeficiency virus-infected subjects. All successfully genotyped cases were due to genotype 4 infection. Conclusions: DBS-based HCV testing represents a useful tool for the diagnosis and surveillance of HCV viremia and can easily be incorporated into specimen referral systems. Among adults ≥40 years of age in the DRC, 100000-200000 may have active infection and be eligible for treatment.

Immune-Escape Mutations Are Prevalent among Patients with a Coexistence of HBsAg and Anti-HBs in a Tertiary Liver Center in the United States.

The concurrent seropositivity of HBsAg and anti-HBs has been described among patients with chronic hepatitis B (CHB), but its prevalence is variable. HBV S-gene mutations can affect the antigenicity of HBsAg. Patients with mutations in the 'α' determinant region of the S gene can develop severe HBV reactivation under immunosuppression. In this study at a tertiary liver center in the United States, we evaluated the frequency and virological characteristics of the HBsAg mutations among CHB patients with the presence of both HBsAg and anti-HBs. In this cohort, 45 (2.1%) of 2178 patients were identified to have a coexistence of HBsAg and anti-HBs, and 24 had available sera for the genome analysis of the Pre-S1, Pre-S2, and S regions. The frequency of mutations in the S gene was significantly higher among those older than 50 years (mean 8.5 vs. 5.4 mutations per subject, p = 0.03). Twelve patients (50%) had mutations in the 'α' determinant region of the S gene. Mutations at amino acid position 126 were most common in eight subjects. Three had a mutation at position 133. Only one patient had a mutation at position 145-the classic vaccine-escape mutation. Despite the universal HBV vaccination program, the vaccine-escape mutant is rare in our cohort of predominantly Asian patients.

Quantitative HBeAg is a strong predictor of HBeAg loss among patients receiving pegylated interferon.

BACKGROUND: HBeAg loss is an important endpoint for antiviral therapy in chronic hepatitis B (CHB), however there are no reliable biomarkers to identify patients who will respond to the addition of pegylated interferon to nucleos(t)ide analogue (NA) therapy. AIM: To evaluate the use of serum biomarkers to predict HBeAg loss. METHODS: HBeAg positive CHB participants on NAs who switched-to or added-on 48 weeks pegylated interferon alpha2b (clinicaltrial.gov NCT01928511) were evaluated at week 72 for HBeAg loss. The predictive ability of qHBeAg, qHBsAg, HBV RNA and clinical variables for HBeAg loss were investigated. RESULTS: HBeAg loss occurred in 15/55 (27.3%) participants who completed 48 weeks of pegylated interferon. There was a lower baseline qHBeAg (1.18 IU/mL [2.27] versus 10.04 IU/mL [24.87], P = 0.007) among participants who lost HBeAg. Baseline qHBeAg (OR = 0.15, 95% CI 0.03-0.66, P = 0.01) and detectable HBV DNA at baseline (OR = 25.00, 95% CI 1.67-374.70, P = 0.02) were independent predictors of HBeAg loss. In addition, on-treatment qHBeAg was also a strong predictor of HBeAg loss (OR = 0.39, 95% CI 0.18-0.81, P = 0.012). The models combining detectable baseline HBV DNA with baseline (C-statistic 0.82) and on-treatment (C-statistic 0.83) had good accuracy for predicting HBeAg loss. A rise in qHBeAg ≥ 10 IU/ml was a predictor of flare (ALT ≥ 120 U/ml) on univariable analysis but not after adjustment for treatment arm. CONCLUSIONS: Baseline and on-treatment qHBeAg is a useful biomarker that can identify participants on NA therapy who may benefit from adding or switching to pegylated interferon.

Large-scale analysis of the prevalence and geographic distribution of HIV-1 non-B variants in the United States.

The genetic diversity of human immunodeficiency virus type 1 (HIV-1) has significant implications for diagnosis, vaccine development, and clinical management of patients. Although HIV-1 subtype B is predominant in the United States, factors such as global travel, immigration, and military deployment have the potential to increase the proportion of non-subtype B infections. Limited data are available on the prevalence and distribution of non-B HIV-1 strains in the United States. We sought to retrospectively examine the prevalence, geographic distribution, diversity, and temporal trends of HIV-1 non-B infections in samples obtained by ARUP Laboratories, a national reference laboratory, from all regions of the United States. HIV-1 pol sequences from 24,386 specimens collected from 46 states between 2004 and September 2011 for drug resistance genotyping were analyzed using the REGA HIV-1 Subtyping Tool, version 2.0. Sequences refractory to subtype determination or reported as non-subtype B by this tool were analyzed by PHYLIP version 3.5 and Simplot version 3.5.1. Non-subtype B strains accounted for 3.27% (798/24,386) of specimens. The 798 non-B specimens were received from 37 states and included 5 subtypes, 23 different circulating recombinant forms (CRFs), and 39 unique recombinant forms (URFs). The non-subtype B prevalence varied from 0% in 2004 (0/54) to 4.12% in 2011 (201/4,884). This large-scale analysis reveals that the diversity of HIV-1 in the United States is high, with multiple subtypes, CRFs, and URFs circulating. Moreover, the geographic distribution of non-B variants is widespread. Data from HIV-1 drug resistance testing have the potential to significantly enhance the surveillance of HIV-1 variants in the United States.

Sequence conservation of the region targeted by the Abbott RealTime HBV viral load assay in clinical specimens.

The Abbott RealTime HBV assay targets the N-terminal region of the S gene. Here we analyzed the sequence variability of the assay target region from >2,100 clinical specimens. Thermodynamic modeling of the percentage of bound primer/probe at the assay annealing temperature was performed to assess the potential effect of sequence variability.

Serological and Molecular Characterization of Occult HBV Infection in Blood Donors from South Italy.

Despite good vaccine coverage and careful blood donor selection policies, hepatitis B virus (HBV) is still the most frequent viral infection among blood donors (BDs) in Italy, mostly in the occult form (OBI). We studied the virological features of OBI in BDs from South Italy by serology, molecular testing for HBV-DNA, and sequencing for HBV genotypes and mutations. One hundred and two samples from 95 BDs (22.1% first time, 87.9% regular, median age 57 years) positive for HBV-DNA and negative for HBsAg were retrospectively analyzed. HBV biomarkers were detected in 96.9% (anti-HBc in 44.2%, anti-HBc plus anti-HBs in 49.5%, anti-HBs alone in 3.2%). No risk factor was declared by 45.3% of donors. HBV-DNA levels were very low (median: 7 IU/mL). All samples harbored HBV genotype D and single or multiple mutations in the S gene were found in 28/36 sequences analyzed and in 75% of donors. Mutations were unrelated to gender, donor group or serological patterns. An HBsAg assay with enhanced sensitivity was positive in samples from seven donors (7.4%), two of which negative for HBV-DNA by real-time PCR. OBI still represents a risk for HBV transmission from blood donations; screening by highly sensitive serological and molecular assays is warranted.

The diversification of SARS-CoV-2 Omicron variants and evaluation of their detection with molecular and rapid antigen assays.

BACKGROUND: The SARS-CoV-2 pandemic saw the rapid rise, global spread, and diversification of the omicron variant in 2022. Given the overwhelming dominance of this variant globally and its diverse lineages, there is an urgent need to ensure that diagnostic assays are capable of detecting widely circulating omicron sub-lineages. STUDY DESIGN: Remnant clinical VTM samples from SARS-CoV-2 PCR confirmed infections (n = 733) collected in Wisconsin (n = 94), New York (n = 267), and South Carolina (n = 372) throughout 2022 were sequenced, classified, and tested with m2000 RealTime SARS-CoV-2, Alinity m SARS-CoV-2, ID NOW COVID-19 v2.0, BinaxNOW COVID-19 Ag Card, and Panbio COVID-19 Rapid Test Device assays. RESULTS: Sequences and lineage classifications were obtained for n = 641/733 (87.4%) samples and included delta (n = 6) and representatives from all major SARS-CoV-2 omicron variants circulating in 2022 (BA.1, BA.2, BA.3, BA.4, BA.5, BE, BF, BQ.1, and XBB). Panels of diverse omicron lineages were tested by molecular assays RealTime (n = 624), Alinity m (n = 80), and ID NOW v2.0 (n = 88) with results showing 100% detection for all samples. BinaxNOW and Panbio had sensitivities of 494/533 (92.7%) and 416/469 (88.7%), respectively for specimens with >4 log10 copies/test, consistent with expected performance for frozen specimens. Furthermore, BinaxNOW demonstrated SARS-CoV-2 detection in clinical samples 1-4 days, and up to 18 days post-symptom onset in BA.1 infected patients with >4 log10 copies/test. CONCLUSIONS: This data highlights the rise and diversification of SARS-CoV-2 omicron variants over the course of 2022 and demonstrate that each of the 5 tested assays can detect the breadth of omicron variants circulating globally.

Detection of SARS-CoV-2 antibodies after confirmed Omicron BA.1 and presumed BA.4/5 infections using Abbott ARCHITECT and Panbio assays.

Background: Commercial severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody tests were developed before variants with spike protein mutations emerged, leading to concerns that these tests have reduced sensitivity for detecting antibody responses in individuals infected with Omicron subvariants. This study was performed to evaluate Abbott ARCHITECT serologic assays, AdviseDx SARS-CoV-2 IgG II, and SARS-CoV-2 IgG for the detection of spike (S) and nucleocapsid (N) IgG antibody increases in vaccinated healthcare workers infected with Omicron subvariants. Methods: During the BA.1/2 and BA.4/5 waves, 171 SARS-CoV-2-infected individuals (122 in the BA.1/2 wave, 49 in the BA.4/5 wave) were tested for S and N IgG post infection. Sequencing and SARS-CoV-2 variant confirmation were performed on nasal swab samples from individuals infected during the BA.1/2 wave. Results: Twenty-seven Omicron sequence confirmed individuals in the BA.1/2 wave and all 49 in the BA.4/5 wave had pre-infection antibody data. Compared to pre-infection levels, post-infection S IgG increased 6.6-fold from 1294 ± 302 BAU/ml (mean ± standard error measurement) to 9796 ± 1252 BAU/ml (P < 0.001) during the BA.1/2 wave, and 3.6-fold from 1771 ± 351 BAU/ml to 8224 ± 943 BAU/ml (P < 0.001) during the BA.4/5 wave. N IgG increased post infection 19.1-fold from 0.2 ± 0.1 to 3.7 ± 0.5 (P < 0.001) during the BA.1/2 wave and 13.5-fold from 0.22 ± 0.1 to 3.2 ± 0.3 (P < 0.001) during the BA.4/5 wave. Among 159 infection-naïve individuals, positive N IgG levels were detected with a sensitivity of 88% in the 87 individuals who were tested between 14 days and 60 days post infection. Conclusions: The large increases in post-infection S IgG along with the N IgG sensitivity that was comparable to previously reported N IgG sensitivity data in unvaccinated individuals after Omicron infection, support the use of Abbott SARS-CoV-2 assays for detecting increased S IgG and seroconversion of N IgG in vaccinated individuals post Omicron infection. Given that 68% of the United States population is fully vaccinated, these results are of current relevance.

Confirmation of putative HIV-1 group P in Cameroon.

We report the second human immunodeficiency virus (HIV) belonging to the new HIV type 1 (HIV-1) group P lineage that is closely related to the simian immunodeficiency virus found in gorillas. This virus was identified in an HIV-seropositive male hospital patient in Cameroon, confirming that the group P virus is circulating in humans. Results from screening 1,736 HIV-seropositive specimens collected in Cameroon indicate that HIV-1 group P infections are rare, accounting for only 0.06% of HIV infections. Despite its rarity, group P shows evidence of adaptation to humans.

Modified ARCHITECT® serologic assays enable plasma-level performance from dried blood spot samples.

Dried blood spots (DBSs) provide an alternative sample input for serologic testing. We evaluated DBSs for the ARCHITECT® hepatitis B surface antigen (HBsAg) NEXT, hepatitis B e-antigen (HBeAg), anti-hepatitis B core antigen (anti-HBc II), HIV antigen/antibody (Ag/Ab) Combo and AdviseDx SARS-CoV-2 IgG II assays. Assay performance with DBSs was assessed with or without assay modification and compared with on-market assay with plasma samples. DBS stability was also determined. HBsAg NEXT and HIV Ag/Ab Combo assays using DBSs showed sensitivity and specificity comparable to that of on-market assays. Modified HBeAg, anti-HBc II and SARS-CoV-2 IgG II DBS assays achieved performance comparable to on-market assays. Use of DBSs as input for high-throughput serologic assays is expected to have significant implications for improving population surveillance and increasing access to diagnostic testing.

Evaluation of hepatitis C virus antibody assay using dried blood spot samples.

Early diagnosis of hepatitis C virus (HCV) infection is essential for prompt initiation of treatment and prevention of transmission, yet several logistical barriers continue to limit access to HCV testing. Dried blood spot (DBS) technology involves a simple fingerstick that eliminates the need for trained personnel, and DBS can be stored and transported at room temperature. We evaluated the use of DBS whole blood samples in the modified Abbott ARCHITECT anti-HCV assay, comparing assay performance against the standard assay run using DBS and venous plasma samples. 144 HCV positive and 104 HCV negative matched venous plasma and whole blood specimens were selected from a retrospective study with convenience sampling in Cameroon. Results obtained using a modified volume DBS assay were highly correlated to the results of the standard assay run with plasma on clinical samples and dilution series (R2 = 0.71 and 0.99 respectively). The ARCHITECT Anti-HCV assay with input volume modification more accurately detects HCV antibodies in DBS whole blood samples with 100% sensitivity and specificity, while the standard assay had 90.97% sensitivity. The use of DBS has the potential to expand access to HCV testing to underserved or marginalized populations with limited access to direct HCV care.

HBsAg isoform dynamics during NAP-based therapy of HBeAg-negative chronic HBV and HBV/HDV infection.

Nucleic acid polymers block the assembly of hepatitis B virus (HBV) subviral particles, effectively preventing hepatitis B surface antigen (HBsAg) replenishment in the circulation. Nucleic acid polymer (NAP)-based combination therapy of HBV infection or HBV/hepatitis D virus (HDV) co-infection is accompanied by HBsAg clearance and seroconversion, HDV-RNA clearance in co-infection, and persistent functional cure of HBV (HBsAg < 0.05 IU/ml, HBV-DNA target not dected, normal alanine aminotransferase) and persistent clearance of HDV RNA. An analysis of HBsAg isoform changes during quantitative HBsAg declines (qHBsAg), and subsequent treatment-free follow-up in the REP 301/REP 301-LTF (HBV/HDV) and REP 401 (HBV) studies was conducted. HBsAg isoforms were analyzed from frozen serum samples using Abbott Research Use Only assays for HBsAg isoforms (large [L], medium [M], and total [T]). The relative change over time in small HBsAg relative to the other isoforms was inferred by the change in the ratio over time of T-HBsAg to M-HBsAg. HBsAg isoform declines followed qHBsAg declines in all participants. No HBsAg isoforms were detectable in any participants with functional cure. HBsAg declines > 2 log10 IU/ml from baseline were correlated with selective clearance of S-HBsAg in 39 of 42 participants. Selective S-HBsAg decline was absent in 9 of 10 participants with HBsAg decline < 2 log10 IU/ml from baseline. Mild qHBsAg rebound during follow-up <10 IU/ml consisted mostly of S-HBsAg and M-HBsAg and not accompanied by significant covalently closed circular DNA activity. Conclusion: The faster observed declines in S-HBsAg indicate the selective clearance of subviral particles from the circulation, consistent with previous mechanistic studies on NAPs. Trace HBsAg rebound in the absence of HBV DNA may reflect HBsAg derived from integrated HBV DNA and not rebound of viral infection.

Highly Sensitive HBsAg, Anti-HBc and Anti HBsAg Titres in Early Diagnosis of HBV Reactivation in Anti-HBc-Positive Onco-Haematological Patients.

The role of novel HBV markers in predicting Hepatitis B virus reactivation (HBV-R) in HBsAg-negative/anti-HBc-positive oncohaematological patients was examined. One hundred and seven HBsAg-negative/anti-HBc-positive oncohaematological patients, receiving anti-HBV prophylaxis for >18 months, were included. At baseline, all patients had undetectable HBV DNA, and 67.3% were anti-HBs positive. HBV-R occurred in 17 (15.9%) patients: 6 during and 11 after the prophylaxis period. At HBV-R, the median (IQR) HBV-DNA was 44 (27-40509) IU/mL, and the alanine aminotransferase upper limit of normal (ULN) was 44% (median (IQR): 81 (49-541) U/L). An anti-HBc > 3 cut-off index (COI) plus anti-HBs persistently/declining to <50 mIU/mL was predictive for HBV-R (OR (95% CI): 9.1 (2.7-30.2); 63% of patients with vs. 15% without this combination experienced HBV-R (p < 0.001)). The detection of highly sensitive (HS) HBsAg and/or HBV-DNA confirmed at >2 time points, also predicts HBV-R (OR (95% CI): 13.8 (3.6-52.6); 50% of positive vs. 7% of negative patients to these markers experienced HBV-R (p = 0.001)). HS-HBs and anti-HBc titration proved to be useful early markers of HBV-R. The use of these markers demonstrated that HBV-R frequently occurs in oncohaematological patients with signs of resolved HBV infection, raising issues of proper HBV-R monitoring.