Acute Hepatitis C: Newly acquired hepatitis C virus (HCV) infection

Anti-HCV:  Antibody to the hepatitis C virus, which develops in response to an HCV infection. It is detectable in persons with acute, chronic, and resolved infection

CD5:  A cell surface molecule found on the B-1 B cells, which express IgM but little or no IgD. CD5 is not an indispensable marker of the B-1 B lineage

CD81:  A cell surface molecule expressed on hematopoeitic, endothelial, and epithelial cells. CD81 is also a member of the CD19/CD21/Leu-13 signal transduction complex (the B-cell coreceptor complex)

Chronic HCV Infection: Persistent infection with HCV, characterized by the detection of HCV RNA at least 6 months after acute hepatitis C

Chronic Hepatitis C: Liver inflammation in patients with chronic HCV infection, characterized by abnormal levels of liver enzymes, such as the alanine aminotransferase (ALT) enzyme

Fibrosis:  A condition marked by an increase in interstitial fibrous tissue

Genotype Diversity: Genetic heterogeneity amongst HCV isolates world-wide, as a result of the accumulation of mutations during the long-term evolution of these viruses 

HCV Positive:  Positive for anti-HCV or HCV RNA

Hepatitis:  Inflammation of the liver

Hepatocellular Carcinoma (HCC):  A cancerous growth or tumor of the epithelial tissues of the liver, comprising malignant cells that are capable of invading surrounding healthy tissues and giving rise to secondary growths (metastases) separate from the original tumor. HCCs tend to spread extensively within the liver, and also grow into the veins of the liver, from which they may spread to more distant sites, such as the lungs 

Hyperimmune Globulin: Antibody produced to a synthetic peptide derived from a hypervariable region (HVR1) of HCV surface glycoprotein E2

Positive Predicted Value: The probability that a positive screening test is truly positive; dependent on the prevalence of disease in a population

Qualitative Polymerase Chain Reaction (PCR) for HCV RNA:  Nucleic acid test to detect HCV RNA by amplification of viral genetic sequences

Quantitative Assays for HCV RNA: Nucleic acid tests to detect HCV viral load by amplification of viral genetic sequences using a quantitative PCR assay, or signal amplification, such as the branched DNA assay

Quasispecies Diversity: Genetic heterogeneity within an infected individual, due to de novo infection with a heterogeneous virus population, or accumulation of mutations during the course of an infection 

Resolved HCV Infection: Recovery following HCV infection, characterized by the disappearance and sustained absence of serum HCV RNA, and the normalization of liver enzymes

Supplemental anti-HCV Test: Additional anti-HCV test (i.e. RIBA: recombinant immunoblot assay) used to verify a positive anti-HCV result obtained by the enzyme immunoassay (EIA)