studies

HEPATOLOGY, VOLUME 62, NUMBER 1 (SUPPL) AASLD ABSTRACTS 1021A
1666
Presence of naïve-like CD8+ T cells specific for subdominant
hepatitis B virus epitopes in chronically infected
patients
Anita Schuch 1,2 , Muthamia Kiraithe 1,2 , Julia Lang 1 , Christoph Neumann-Haefelin
1 , Robert Thimme 1 ; 1 Department of Medicine II, University
Hospital Freiburg, Freiburg, Germany; 2 Faculty of Biology,
University of Freiburg, Freiburg, Germany
In chronically HBV-infected patients, virus-specific CD8+ T
cells are rarely detectable ex vivo by conventional tetramer
stainings. We aimed to analyze whether his lack of HBV-specific
CD8+ T-cell responses may be explained by insufficient
priming or terminal deletion. To phenotypically characterize
HBV-specific CD8+ T cells that are not detectable by conventional
methods we used a combination of tetramer-associated
magnetic bead enrichment and multiparametric flow cytometry
and additionally performed viral sequence analyses. We analyzed
CD8+ T-cell populations specific for 4 well-described
HLA-A*02:01 restricted HBV epitopes (Core 18-27
, Env 183-191
,
Env 335-343
and Pol 455-463
) in a heterogeneous cohort of 34
chronically HBV-infected patients. We were able to detect 108
of 136 (79%) HBV-specific CD8+ T-cell populations. Of note,
each patient had at least one detectable CD8+ T-cell population,
suggesting that these cells are not completely deleted
in chronic infection. Enriched CD8+ T cells specific for the
immunodominant Core 18-27
epitope predominantly showed an
antigen-experienced effector-memory phenotype (CD45RA - ,
CCR7 - , CD27 + , CD11a + ) which was also detectable in patients
with resolved HBV infection. In contrast, CD8+ T cells specific
for Env 183-191
, Env 335-343
and Pol 455-463
often displayed a naïvelike
phenotype (15%, 44% and 19% respectively) defined by
high expression of CD45RA, CCR7 and CD27. Absence of
CD11a and CD95 expression additionally indicated a naïve
status of these enriched HBV-specific CD8+ T cells. Importantly,
the presence of wild type sequences in patients with naïve-like
HBV-specific CD8+ T cells indicated that the presence of naïvelike
cells is not due to infection with a variant HBV containing
mismatched epitopes. It is also important to note that the presence
of HBV-specific CD8+ T cells with naïve-like phenotype
did not correlate with any clinical parameter such as viral load,
transaminase levels or HBeAg status, and was independent
of antiviral treatment. Taken together, our results indicate that
HBV-specific CD8+ T cells are not completely deleted in chronically
infected patients, but are rather maintained at a very low
frequency. Furthermore, a substantial fraction of CD8+ T cells
specific for subdominant HBV epitopes display a naïve-like
phenotype despite ongoing viral replication. This suggests that
insufficient priming and/or antigen ignorance of HBV-specific
CD8+ T cells may also contribute to CD8+ T-cell failure in
chronic HBV infection and that therapeutic vaccination may be
a feasible approach in this patient cohort.
Disclosures:
Christoph Neumann-Haefelin - Advisory Committees or Review Panels: AbbVie;
Speaking and Teaching: AbbVie, Gilead, Bristol-Myers Squibb
The following authors have nothing to disclose: Anita Schuch, Muthamia Kiraithe,
Julia Lang, Robert Thimme
1667
Precore and Basal Core Promoter mutations in HBeAg
negative chronic hepatitis B virus infection in Cape
Town, South Africa
Mark W. Sonderup 1 , Heidi Smuts 2 , Ruud A. Roos 3,1 , Helen
Wainwright 4 , Neliswa A. Gogela 1 , Mashiko Setshedi 1 , Henry N.
Hairwadzi 1 , C. W. Spearman 1 ; 1 Department of Medicine and
Division of Hepatology, University of Cape Town, Cape Town,
South Africa; 2 Division of Medical Virology, University of Cape
Town and NHLS, Cape Town, South Africa; 3 Vrije Universiteit,
Amsterdam, Netherlands; 4 Department of Anatomical Pathology,
University of Cape Town, Cape Town, South Africa
Chronic HBeAg negative HBV represents the immune control
or escape phase of infection. Precore (PC) and basal core
promoter (BCP) mutations are associated with progressive liver
disease or HCC although this is poorly studied in sub-Saharan
Africa. Our aim was to characterize mutations in HBeAg negative
patients. Methods: Prospectively, over 2 years, HBeAg negative
patients were analysed by amplifying viral PC and BCP
regions using nested primers. Amplicons were direct Sanger
sequenced in the forward & reverse directions and compared
to reference sequences. Relevant demographic, clinical, virological
and histological data were captured. Results: 124
patients, median age 35.1 yrs (IQR 29-43.2), 60.5% (n=75)
male, 3.2% (n=4) HIV co-infected, were analysed. Ethnically,
52% were mixed ancestry, 28% Black African, 16% White
and 4% Asian. Genotype distribution - A 51%, B 2.3%, C
1.1%, D 42% and E 3.6%. Mutations were detected in 98.4%
(n=122); 89% (n=109) with PC; 53.3% (n=65) BCP and 46%
(n=56) both. Mutation frequencies are listed. Median ALT (U/L)
was significantly higher when both PC/BCP than PC only mutations
were present, [44 (IQR 41-47); 27 (19-52)] p=0.0007,
but not with BCP only mutations [32 IQR (22-65)]; p=0.069.
With dual A1762T G1764A BCP mutations, median ALT and
HBV DNA (log 10
IU/ml) was significantly higher compared to
the T1753C only BCP mutation, [52 (IQR 25-134); 24 (IQR21-
49)]; p=0.019 and [5.2 (IQR 4-7.6); 3.8 (3-5.3)]; p=0.02.
In those biopsied (n=31), median Ishak necro-inflammatory
stage and fibrosis grade scores were 5 (IQR 3-7) & 2 (IQR 1-3)
respectively with no differences observed in PC, BCP or PC/
BCP groups. Six patients, 4.8%, developed HCC with 5 (83%)
having both PC/BCP mutations, 3 (50%) the dual A1762T
G1764A BCP mutation and 4 (66%) the G1896A PC mutation.
Conclusion: In HBeAg negative, mostly A or D genotype CHB
patients, PC were present more frequently than BCP mutations;
almost half having both. Dual PC/BCP predicted for higher ALT
and HBV DNA; a similar trend observed for the dual A1762T
G1764A BCP mutation. Mutation analysis may have a role in
guiding the need for antiviral therapy.