Hepatitis B Vaccine Genetics: A Substudy of ATN 024 and ATN 025

This laboratory-based substudy of ATN 024 and 025 will evaluate the genetic contribution to
highly individualized immune responses to hepatitis B vaccine in individuals and confirm the
correlation of specific human leukocyte antigen (HLA) alleles and haplotypes with Hepatitis
B Virus (HVB) antibody concentrations and antibody decay kinetics in vaccinated adolescents.
Approximately 5 ml of whole blood will be collected from study participants at the time of
the week 28 visit or at any subsequent study visit or clinic visit following successful
completion of the week 28 visit. Peripheral blood mononuclear cells will be obtained and QIA
amp Blood kit will be used to extract high-quality genomic DNA for polymerase chain
reaction-based genotyping by the PEII laboratory.

The study is expected to be available for the duration of the parent studies which is
approximately 2 years. This study requires one visit that may be arranged to coincide with a
study or routine clinic visit. There are no follow up visits.

Inclusion Criteria:

- Subjects currently enrolled in ATN 024 or ATN 025 are eligible for enrollment in ATN
052 beginning at or following completion of the week 28 visit.

- Subjects previously enrolled in ATN 024 or ATN 025 are eligible for enrollment in ATN
052, unless the subject was prematurely discontinued from the study prior to the
first post-vaccination serology assessment which is performed at week 28.

- Current pregnancy is permitted.

- A signed informed assent/consent must be obtained from the subject.

- Written parental or guardian permission must be obtained where required by the
institutional review board/ethics committee (IRB/EC).

Exclusion Criteria:

- Inadequate post-vaccination serology evaluation in ATN 024 or ATN 025.

- Unable to obtain informed consent and/or parental/legal guardian permission where
required by the local IRB/EC.