subject: Human Papillomavirus [print this page] Human Papillomavirus Human Papillomavirus
HPV (human papillomavirus) is commonly a sexual transmitted infection. There are about forty different types of human papillomavirus that can infect both men and women genital areas, including the vulva, skin, penis, cervix, vaginal lining, rectum, and even the anus. This virus can not be seen and most individuals who are infected with the virus hardly know that they actual have it. Most individuals with human papillomavirus never develop health problems or symptoms (Medscape Medical News, 2009). However certain type of human papillomavirus can lead to genital wart in women and men. Other types of human papillomavirus can result into cancer of the cervix as well as other unusual cancers like cancers of the vagina, vulva, penis, and anus. The types of human papillomavirus that lead to genital wart are different from those which cause cancer. Therefore types of HPV are frequently referred to as high risk' (cancer cervical causing) or low risk' (wart causing), depending on whether they expose an individual at danger of cancer. 90% of the human papillomavirus cases are naturally cleared by the individual's immune system within the 2 years (OCF INC, 2009).This applies to both low risk and high risk types.
Life cycle of the causative agent
Generally, a virus has RNA or DNA genetic materials which are enclosed in the protein capsule. As a virus makes contact with an individual cell, it inserts its RNA or DNA materials in the host cell, after invading the host cell, it can therefore undergo lytic or lysogenic phase. Throughout the phase of lysogenic, this virus stays inactive in the cell and does not impinge on the host cell (Medscape Medical News, 2009). Host cell carries on with its normal functions, regardless of the virus invasion. However, the host cell is taken over by the virus during the lytic phase and utilizes this host cell in reproducing numerous viruses which as a result invade and infect more cells. At this lytic stage the genetic material of the viruses conquest the functions of the cell as well as controlling of the reproductive process (Hanissian, 1997). The host cell is then ordered by the viral heritable material to produce several copies of the viral RNA or DNA and proteins. Viral proteins are then assembled in the protein coats, and viral genetic materials (DNA or RNA) are packed within the coats. This leads to production of numerous viruses within the host cell. After completion of this viral reproductive process, the host passes on and the just produced viruses are unconstrained, thereby affecting more host cells (OCF INC, 2009).
Unlike bacteria, viruses can never be harmed, destroyed, or destructed by antibiotic. Though currently there is no cure to eradicate infection resulting from papilloma virus, warts and squamous intraepithelial lesions (SILS) can be treated. The methods used in treating SILS include convectional surgery, cold cautery, and laser treatment (Hanissian, 1997). Once an individual is infected by the virus, this human papillomavirus may become individual/organism for an indefinite period although it is not understood if the virus enters the phase of dormancy maybe for even decades, or if it's destroyed by the immune system and invariable re-infection takes place.
Therefore, the life cycle of human papillomavirus is associated with the skin keratinocytes differentiation, with a primary infection only taking place in undifferentiated compartment of the epithelium as well as progeny of virus production in the terminally differentiated compartment only (Medscape Medical News, 2009). Currently, little information is known about how the life cycle of human papillomavirus is restricted by the host cells to definite phases of skin cell growth. However, it was discovered that progression of the cell cycle via the process of mitosis is critical and at the same time crucial in establishing the HPV infection (Hanissian, 1997).
Current Control Methods
Testing individuals for HPV is the most effective methods of controlling this virus, more especially in the developing countries. Visual inspection and cytological testing are important in reducing the prevalence of cancer of the cervix and other human papillomavirus associated conditions (Lowy and Schiller, 1998). Therefore, the international experts in cancer of the cervix are trying to advocate for the HPV testing as away of controlling the virus. For example lack of human papillomavirus testing programs in most of developing countries has lead upsurge of the virus hence amplifying the incidence of cervical cancer and other unusual cancers caused by papilloma virus. The early detection as well as treatment of resulting lesions from the advanced cancer can lower greatly the invasive cancers and deaths emanating from the cervical cancer. The drawback of this method is that it is time consuming and expensive to many people especially those from developing nations (Medscape Medical News, 2009).
Another method which is currently used in an attempt to control the infection of human papillomavirus is vaccination. Vaccine, such as Gardasil and Cervarix are used in protecting against four strains of HPV that cause several cases of genital warts and cervical cancer. Center for Disease Control (CDC) in 2007 included Gardasil as part of childhood vaccines to girls aged between eleven to twelve in three doses, plus catch-up doses for women who had never been vaccinated previously and fall between the age of 13 and 26 (Lowy and Schiller, 1998). However, many health professionals are doubtful of the HPV vaccine, alleging that several materials supplied to them failed to appropriately substantiate the cons and pros of the vaccine. Some of the adverse side effects of getting this vaccine shot include headaches, nausea, fainting, or skin rash. High costs in accessing the HPV vaccine is one of the major drawbacks of this particular contort method.
Evidence of safety and efficacy of HPV vaccine
The final trial has established that a bivalent vaccine is extremely efficient at protecting against HPV strains 16 and 18. The vaccine which is produced by GlaxoSmithKline under the licensed name Cervarix was efficient at protecting individuals against cervical lesions linked to both strains16 and 18 of human papilloma virus together with lesions which were connected with non vaccine types, such as HPV-31, HPV-33, and HPV-45 Laura and Katherine, 2003). Also the three year follow up of women in HPV vaccine indicated that the Cervarix vaccine was, normally well tolerated, extremely immunogenic, and highly active against human papillomavirus infection as well as associated lesions.
A team from the University of Johns Hopkins found out the L2 fusion proteins vaccine produced substantial levels of antibodies against a number of human papillomavirus types (Lowy and Schiller, 1998).Though, they noted that L2 never induced antibodies against HPV -16 in comparison to other vaccines such as Cervarix, with application of adjuvants, such as alum, L2 will be able to induce the neutralizing antibodies against HPV type 16 infection. Clinical studies are needed therefore, to assess the immunogenicity and safety of alum-L2 formulation.
