Human Pappiloma Virus

• DsDNA, Circular genome• Associated with cervical , anal, vaginal,, subset of

head and neck cancer• High risk HPV• Low Risk HPV

High risk type- Cervical cancer

• HPV 16, 18, 31 & 45• Causal agents of 80% of cervical cancer• 2nd most cancer in women with 493,243 new

cases worldwide, 230,000 deaths every year• Prevalence: Europe, North America, and Australia

(74 to 77%)• Africa, Asia, and South/Central America (65 to

70%)

How cervical cancer develops

The life cycle of HPV

How to prevent HPV

• Prophylactic and Therapeutic vaccine• Specific for high risk type• Difference between Prophylactic and therapeutic

vaccine

Prophylactic vaccines

• Polyvalent VLP prophylactic vaccine***

• Live vaccine vectors

• L2 based vaccine

Polyvalent VLP prophylactic vaccine

(Commercially available vaccines)CERVARIX & GARDASIL

• Two pharmaceutical companies: GlaxoSmithKline (GSK) and Merck

• GSK Vaccine-CERVARIX-targets-HPV16, HPV18

• FDA Approved for 10-25 yrs age women

• Merck Vaccine-GARDASIL- targets- HPV 6, 11, 16, 18

• FDA approved for 9-26 yrs age men and women

Therapeutic vaccines• Targets the early proteins• For e.g DNA Vaccines•  MEL-1, created by Dr. Ricardo Rosales.

HISTORY OF HPV VACCINE

• Epidemiological studies, made in 1990, showed that a consistent association between Human Papilloma Virus and Cervical Cancer existed.

• Nearly 16 years later, in 2006, the first vaccine to prevent infection for four types of HP Virus was licensed.

• A Quadrivalent Human Papillomavirus (Types 6, 11, 16, 18) recombinant vaccine (HPV4) was licensed for use in females by the Food and Drug Administration in 2006 and a bivalent vaccine (Types 16 & 18) (HPV2) in 2009.

How does it work?• Both types of vaccine,  Cervarix (GSK) and

Gardasil (Merck), are inactivated vaccines.

• An inactivated vaccine (or killed vaccine) consists of virus particles which are grown in culture and then killed using a method such as heat or formaldehyde

Mechanism of the vaccine

• The HPV vaccine is based on the hollow virus like particles (VLP) that are assembled from recombinant HPV coat proteins.

• The virus has a double stranded DNA and a viral shell having 72 capsomeres.

• Every subunit of the virus has two protein molecules, L1and L2.

• The proteins ensure that numerous copies are made within the host cell.

• Affinity of the virus is dependant on its structure, thus such knowledge of structural components is vital for effective vaccine production.

Cervarix Mechanism

Cervarix is created using the L1 protein of the viral capsid using a Baculovirus expression

system which uses Hi-5 Rix4446 cells derived from the insect Trichoplusia ni. The vaccine

contains no live virus and no DNA, so it cannot infect the patient.

Gardasil Mechanism

Gardasil contains recombinant VLPs assembled from the L1 proteins of HPV types 6, 11, 16 and 18. 

The L1 proteins are produced by separate fermentations in recombinant

Saccharomyces cerevisiae and self-assembled into VLPs

• Gardasil and Cervarix are designed to elicit virus-neutralizing antibody 

• responses that prevent initial infection with the HPV types represented in the vaccine.

• The protective effects of the vaccine are expected to last a minimum of 4.5 years after the initial vaccination

Therapeutic Vaccine for HPV

•  In general these vaccines focus on the main HPV oncogenes, E6 and E7. Since expression of E6 and E7 is required for promoting the growth of cervical cancer cells (and cells within warts), it is hoped that immune responses against the two oncogenes might eradicate established tumors.

MEL-1 (or MVA-E2 Vaccine)

• This working therapeutic HPV vaccine has been clinically tried in Mexico.

• It is a MVA based vaccine with an e2 bovine protein added in. It has been shown to completely eliminate HPV to the point that patients test negative for the presence of HPV in blood tests.

• The vaccine is officially called the MEL-1 Vaccine but also known as the MVA-E2 vaccine

• Clinical trials are still underway, in mexico.

• Clinical Trials• Efficacy• Limitations• Side effects• Future prospects and

improvements• Current Research

Clinical Trials of Gardasil

• Merck & Co. conducted a Phase III study named as (FUTURE II).

• This clinical trial was a randomized double-blind study with one controlled placebo group and one vaccination group.

• Over 12,000 women aged 16–26 from thirteen countries participated in the study. Each woman was injected with either Gardasil or a placebo on day 1, month 2, and month 6. In total, 6,082 women were given Gardasil and 6,075 received the placebo.

• Subjects in the vaccine group had lower occurrence of high-grade cervical intraepithelial neoplasia (CIN) related to HPV-16 or HPV-18 than did those in the placebo group.

• On February 27, 2007, clinical trials were terminated on ethical grounds, so that young women on placebo could receive Gardasil.

Clinical Trials of Cervarix

• Phase III trials have been conducted by GlaxoSmithKline, including over 18,000 women from 14 countries in Pacific Asia, Europe, Latin America and North America

• In 2009 the manufacturer conducted a trial to compare the immunogenicity and safety of Cervarix with Gardasil.

• The studies showed Cervarix generated higher levels of antibodies than Gardasil, upon testing seven months later, with twice the level for HPV type 16 and six times for HPV type 18.

• Cervarix also induced twice as many memory B cells as Gardasil for both these HPV strains.

Efficacy• Both Gardasil and Cervarix have been shown to

prevent cervical dysplasia from the high-risk HPV types 16 and 18 and some protection against a few closely related high-risk HPV types.

• Other high-risk HPV types are not affected by the vaccines.

• The protection against HPV 16 and 18 strains has lasted 5 years after vaccination for Gardasil and more than 6 years for Cervarix (7.3 years).

• Gardasil also protects against low-risk HPV types 6 and 11, which do not cause cancer, but do cause genital warts.

Limitation• Cervarix does not provide protection against

disease caused by all HPV types, nor against disease if a woman has previously been exposed to the virus through sexual activity. It is therefore recommended that women continue to adhere to cervical cancer screening procedures.

• 30% of cervical cancers will not be prevented by these vaccines. Gardasil also fails to treat 10% genital warts.

Side Effects

• pain, swelling, redness, bruising, or itching where the shot was given;

• mild fever, headache, dizziness, tired feeling;

• nausea, vomiting, diarrhea;• sleep problems (insomnia);• runny or stuffy nose, sore throat, cough;• tooth pain, joint or muscle pain.

Improvement for future

• The vaccines should become effective against strains other then strain 16 and 18.

• The vaccines effect should last longer than 5 years. Preferably for a lifetime.

• The required dosage should be reduced, from 3 dosages to only 1 dosage that protects a person for a lifetime.

• The vaccine should work against curing existing HPV infections and cancer.

• They should become a cancer vaccine from STD vaccines.

Current Research• An investigational nonavalent (types 6, 11, 16,

18, 31, 33, 45, 52, and 58) vaccine produced by Merck & Co. called V503 is awaiting approval from the FDA.

• In a phase 3 clinical trial, V503 provided comparable protection to the four types that Gardasil protects against as well as a 97% reduction in cases of high-grade cervical, vulvar and vaginal diseases of five additional HPV types that are considered high-risk for developing cancer.