antigen-a usually protein or carbohydrate substance (as a toxin or enzyme) capable of stimulating an immune response

antigen presenting cells- a heterogeneous group of immunocompetent cells that mediate cellular immune response by processing and presenting antigens to the T-cell receptor. Traditional antigen-presenting cells include macrophages, dendritic cells, langerhans cells, and B- lymphocytes.

CCC DNA- covalently closed circular (CCC) duplex DNA located in the nucleus of an infected host that is stably complexed with a variety of host proteins and forms a viral chromatin species

constimulatory molecules- molecules such as B7-1, B7-2, and 4-1BB ligand to augment the generation of  anti-tumour and other more general  immunity

cytokines- a unique family of growth factors. They are secreted primarily from leukocytes and stimulate both the humoral and cellular immune responses, as well as the activation of phagocytic cells. Cytokines that are secreted from lymphocytes are termed lymphokines. A large family of cytokines are produced by various cells of the body

cytotoxic T cells- a subset of T lymphocytes that can kill body cells infected by viruses or transformed by cancer.

epitope- a molecular region on the surface of an antigen capable of eliciting an immune response and of combining with the specific antibody produced by such a response

hepatocelluar carcinoma (HCC)- cancer that arises from hepatocytes, the major cell type of the liver. It is especially prevalent in parts of Asia and Africa. About 80% of people with hepatocellular carcinomas have cirrhosis. Chronic infection with the hepatitis B virus and hepatitis C virus also increases the risk of developing hepatocellular carcinoma.

humoral immune response- the part of immunity or the immune response that involves antibodies secreted by B cells and circulating in bodily fluids

immunocompromised- a condition in which the immune system is not functioning normally because it was previously damaged by disease or medications

interferon- a protein produced by animal cells when they are invaded by viruses that is released into the bloodstream or intercellular fluid to induce healthy cells to manufacture an enzyme that counters the infection.

major histocompatibility complex (MHC) class I- molecules that bind peptide fragments derived from proteolytically degraded proteins endogenously synthesized by a cell. Small peptides are transported into the endoplasmic reticulum where they associate with nascent MHC class I molecules before being routed through the Golgi apparatus and displayed on the surface for recognition by cytotoxic TC lymphocytes.MHC class I expression is widespread on virtually every cell of the body. This is consistent with the protective function of cytotoxic TC lymphocytes which continuously survey cell surfaces and kill cells harboring metabolically active microorganisms.

major histocompatibility complex (MHC) class II-  molecules that bind peptide fragments derived from proteolytically degraded proteins exogenously internalized by "antigen presenting cells," including macrophages, dendritic cells, and B cells. The resulting peptide fragments are compartmentalized in the endosome where they associate with MHC class II molecules before being routed to the cell surface for recognition by helper TH lymphocytes. MHC class II expression is restricted to "antigen presenting cells." This is consistent with the functions of helper TH lymphocytes which are locally activated wherever these cells encounter macrophages, dendritic cells, or B cells that have internalized and processed antigens produced by pathogenic organisms.

nucleocapsid-a unit of viral structure, consisting of a capsid (protein coat) with the enclosed nucleic acid; some simple viruses are naked nucleocapsids, while in others the nucleocapsids form part of a more complex structure.

oligonucleotide-a polymer made up of a few (2-20) nucleotides. In molecular genetics, a short sequence synthesized to match a region where a mutation is known to occur, and then used as a probe (oligonucleotide probe).

polyadenylation-the addition of several hundred A nucleotides to the 3' ends of mRNAs

prophylactic vaccination- a vaccination which provides protection from disease cauing agents

pregenome- generally refered to as 3.5-kb RNA and has a length exceeding that of the genome due to a short terminal redundancy caused by transcriptional readthrough of a circular genome.

T cell receptor (TCR)-  a complex of integral membrane proteins that participates in the activation of T cells in response to the presentation of antigen.

viremia- the presence of virus in the blood of a host