Viral Hepatitis

Viruses are organisms that are living in the sense that they can reproduce but they are entirely dependent on other and larger organisms for the environment in which this reproduction can occur. In fact all of the larger organisms, bacteria, plants and animals are 'infected' with a multiplicity of viruses. The virus particles having (by quite specific devices much more complicated than a mortise lock) gained entry to the cells of their host organisms have the capacity to invade and become incorporated in the genetic material of the host and there provide the instructions for viral replication.

It is tempting to think of viral infection as being necessarily detrimental to the host organisms but this is probably far from the truth and, as was pointed out many years ago by Todaro,  it could be that many of the properties of higher organisms and particularly human beings depend upon the acquisition and control of viruses and their genetic material. Be this as it may it is quite clear that viral infection can be harmful, as is implicit in the definition of the word infection

Here our interest is in a set of potentially harmful viruses that can invade human beings and have particularly nasty impact on the liver. Like many viral infections these organisms that cause problems in the liver usually do so as a consequence of chronic long term infection. The condition they cause is referred to as viral hepatitis by which is implied creation by a virus of an inflammatory condition of the liver. The viruses are distinguished by the names A, B, C, D and E. HepA, HepB and HepC, as they are commonly called, though they have many other synonyms,  are different viruses that cause rather different patterns of disease. HepD and HepE are organisms related  to each other but not to HepA, HepB and HepC. HepD and HepE are probably relatively rare and they will not be further considered here.

One of the characteristics of viral infections, particularly those which cause acute diseases of childhood, such as measles, mumps, rubella, and poliomyelitis is that they can be successfully vaccinated against.  By this is meant that exposure often to an attenuated living virus which rarely if ever has harmful consequences, results in a state called immunity such that exposure to the wild-type harmful organism will have no adverse consequences. The usual way of thinking about this is that there is elicited by the attenuated virus an immune  response which enables the pathogenic (harmful) wild type organism to be kept out. The truth may be rather different in that the wild type organism may get in and stay in but simply not elicit from the host a reaction that is harmful. Whatever the mechanism the system of vaccination works and, in the present context, it should be noted that reasonably successful schemes of vaccination have been developed for HepA and HepB but not for HepC which is the target of attention here.

HepC was only discovered recently and it is associated particularly with transfer of blood from one individual to another often by dirty needles. It is essentially a disease arising from bad medical practice or from, for example, the use of dirty syringes and needles by drug addicts. It might be thought that a disease transmitted in such a way could be ignored but in fact there are nearly three hundred million people infected with HepC world-wide  and it is a major public health problem not only in developing countries but also in what we tend to think of as the developed, Western, world.

Most of those infected with HepC do not know they have the virus because in many though not all instances there are no signs that the virus has been adopted. In some instances those infected  carry the virus without symptoms for the rest of their lives without any problems except of course their blood will be capable of infecting others. In all too many cases those infected often after ten years and sometimes much more begin to show cirrhosis of the liver with all its attendant dangers. Some of these infected individuals will in addition or instead develop hepatocellular carcinoma. The outlook for those infected with HepC is presently poor though there are some indications that medical treatments can be effective in helping the body to eliminate the offending virus.

Vaccination is in its usual mode is provided as prophylaxis designed to be effective before encounter with the pathogenic wild-type organism. For many reasons such a strategy is not feasible in relation to HepC vaccination and the only possibility is to consider what is becoming to be called therapeutic vaccination for those found to be infected when the virus or anti-viral  antibodies has been found in the blood.

This is the strategy that Professor Habib has adopted and he is involved in the development of appropriate agents of such vaccination.

In addition experiments are being undertaken to determine whether the balance of the interaction between the host and the virus can be tipped in favour of the host either by chemical intervention and/ by the use of specific anti-viral agents such as interferon. it has however to be noted that there is considerable evidence the HepC is resistant to standard forms of interferon though it may be sensitive to the pegylated form.