CHAPTER ONE
INTRODUCTION
1.1     INTRODUCTION TO HEPATITIS B
Viral hepatitis is a disease as old as the history of Medicine. Hepatitis was described in the Babylonian Talmud in the fifty century BC, and was referred to by Hippocratic over 2000 years ago. Despite this ancient knowledge, it was not until 1963, that the first human Repetitious virus was isolated, Hepatitis B. This was followed quickly by the purification of Hepatitis A in 1973, and more recently by the isolation of viruses C, D, E and G. These viruses are known to infect the human liver (Anderson et al; 2001).
However, there are more than twenty other viruses, which infect the human liver. These are not considered “Repatitis viruses” as these other viruses tend to infect organs other than the liver more seriously’. These include common viruses such as Cytomegalovirus (CMV), Mumps, Rubella, Epstein-Barr virus (EBV) as well as rare ones such as Rassa fever and yellow fever viruses.
Any infection that results in inflammation of the liver is called Repatitis (Greek Repaticus, liver). Incidentally, not all “hepatitis” is caused by viruses. “HEPATITIS” means “inflammation of the liver”, and can be caused also by other types of infection (bacteria fungi etc); toxic drugs; poisons; alcoholism and so on (Drexott etal; 2005).
But of interest is one Repatitis virus – one of the most common infections diseases, causing an estimated 1.5millon deaths world wide each year – Hepatitis B. Hepatitis B is caused by the Repatitis B virus (HBV), a double – stranded circular DNA virus of complex structure. Hbv is class ivied as an orthoropadnavirus within the family hepadnaviridae. HBV was originally recognized as the age responsible or serum Repatitis the most common form of partially transmitted viral Repatitis and an import cause of acute and chronic infection of the liver. This why hepatitis b is some times called seum Repatitis. The virus was formerly and anilines referred to as Australian antigen. The reason being that it was first isolated room the blood of an Australian aborogie and is associated with HBV. (procott et al 2005.
Hepatitis B remain one of the major cause of human suffering in the world despite a through understanding of its transmission and prevention. Serum form undivided infected with hepatitis B contains three district antigen  particles: a spherical 22nm particle, a 42 nm  spherical particle ( counting DNA  and DNA polymer able) called  the Dane particle, and tubular or filamentous particles that vary in length. The small spherical and tubular particles  are the unassembled component of the Dane particle- the infective form of the virus. The unassembled particles. Contain hepatitis B surface antigen (HBsAg) whose presence in the blood is (a) an indicator of Repatitis B infection (b) the basis for the large scale screening of blood for the hepatitis B virus, and (c) the basis for the first vaccine for human use developed by recombinant DNA technology (Evans, 1997