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ONCOGENIC VIRUS

A Concise Presentation

By

Mr. Deepak Sarangi M.Pharm

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Introduction Discovery of viruses History What is cancer How viruses cause cancer Growth of cancer cells Classification of oncogenic virus Mechanism of oncogenic virus Drugs used to treat oncogenic viruses Precautions to prevent infection during cancer treatment Conclusion References

CONTENTS

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An oncovirus is a virus that can cause cancer. This term originated

from studies of acutely transforming retroviruses in the 1950–60s,

often called oncornaviruses to denote their RNA virus origin.

Now refers to any virus with a DNA or RNA genome causing

cancer and is synonymous with "tumor virus" or "cancer virus".

The vast majority of human and animal viruses do not cause

cancer, probably because of long-standing coevolution between the

virus and its host.

INTRODUCTION

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Worldwide, the WHO International Agency for Research on

Cancer estimated that in 2002, 17.8% of human cancers were

caused by infection, with 11.9% being caused by one of seven

different viruses.

The importance of this is that these cancers might be easily

prevented through vaccination (e.g., papillomavirus vaccines),

diagnosed with simple blood tests, and treated with less-toxic

antiviral compounds.

CONT...

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1908: Vilhelm Ellerman and Olaf Bang, University of

Copenhagen, first demonstrated that avian sarcoma leukosis

virus could be transmitted after cell-free filtration to new

chickens, causing leukemia.

1933: Richard Edwin Shope discovered cottontail rabbit

papillomavirus or Shope papillomavirus, the first mammalian

tumor virus.

1957: Sarah Stewart and Bernice Eddy discovered polyoma

virus.

DISCOVERY OF VIRUSES

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1964: Anthony Epstein, Bert Achong and Yvonne Barr identify the

first human oncovirus from Burkitt lymphoma cells. A herpesvirus,

this virus is formally known as human herpesvirus 4 but more

commonly called Epstein-Barr Virus or EBV.

1980: Human T-lymphotropic virus 1 (HTLV I), the first human

retrovirus was discovered by Bernard Poiesz and Robert Gallo at NIH

and Mistuaki Yoshida and coworkers in Japan.

2008: Chang and Moore, now at the University of Pittsburgh Cancer

Institute, developed a new method to identify cancer viruses based on

computer subtraction of human sequences from a tumor

transcriptome, called digital transcriptome subtraction (DTS).

DISCOVERY OF HUMAN ONCOVIRUSES

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The theory that cancer could be caused by a virus began with the

experiments of Oluf Bang and Vilhelm Ellerman in 1908 who

first show that avian erythroblastosis (a form of chicken

leukemia) could be transmitted by cell-free extracts. This was

subsequently confirmed for solid tumors in chickens in 1910-

1911 by Peyton Rous.

By the early 1950s it was known that viruses could remove and

incorporate genes and genetic material in cells. It was suggested

that these new genes inserted into cells could make the cell

cancerous. Many of these viral oncogenes have been discovered

and identified to cause cancer.

HISTORY

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Cancer results from alterations in critical

regulatory genes that control cell proliferation,

differentiation, and survival. Studies of tumor

viruses revealed that specific genes (called

oncogenes) are capable of inducing cell

transformation, thereby providing the first

insights into the molecular basis of cancer.

WHAT IS CANCER

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The viral agents causing cancer in eukaryotic animals by integrating in host genome.

A virus associated with malignancies in natural host, experimental animals or cell cultures.

viruses which modified proto- oncogene, obligatory host specific, with the ability immortalization, possess genes which stimulate growth and cause cancer.

HOW VIRUSES CAUSE CANCER

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GROWTH OF CANCER CELLS

Classification

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Oncovirus

DNA oncogenic viruses

RNA oncogenic viruses

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Human papilloma virus (HPV), a DNA virus, causes transformation

in cells through interfering with tumor suppressor proteins such as

p53.

Kaposi's sarcoma-associated herpesvirus (KSHV or HHV-8) is

associated with Kaposi’s sarcoma, a type of skin cancer.

Epstein-Barr virus (EBV or HHV-4) is associated with four types of

cancers.

Merkel cell polyomavirus – a polyoma virus – is associated with the

development of Merkel cell carcinoma.

Human cytomegalovirus (CMV or HHV-5) is associated with

mucoepidermoid carcinoma and possibly other malignancies.

DNA ONCOGENIC VIRUSES

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Not all oncoviruses are DNA viruses. Some RNA viruses have

also been associated such as the hepatitis C virus as well as

certain retroviruses, e.g., human T-lymphotropic virus (HTLV-1)

and Rous sarcoma virus (RSV).

RNA ONCOGENIC VIRUSES

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VirusPercent of

cancersAssociated cancer types

Hepatitis viruses, including hepatitis B (HBV) and hepatitis C (HCV)

4.9Hepatocellular carcinoma (liver cancer).

Human T-lymphotropic virus (HTLV) 0.03 Adult T-cell leukemia

Human papillomaviruses (HPV) 5.2Cancers of cervix, anus, penis, vulva/vagina, and oropharyngeal cancer.

Kaposi’s sarcoma-associated herpesvirus (HHV-8)

0.9Kaposi’s sarcoma, multicentric Castleman's disease and primary effusion lymphoma

Merkel cell polyomavirus Not available Merkel cell carcinoma

Epstein–Barr virus (EBV) Not available

Burkitt’s lymphoma, Hodgkin’s lymphoma, Post-transplant lymphoproliferative disease and Nasopharyngeal carcinoma.

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MECHANISM OF ONCOGENIC VIRUS

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DRUGS USED TO TREAT ONCOGENIC VIRUSES

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Wash your hands after using the bathroom, blowing your nose,

coughing, or sneezing.

Wash your hands after touching animals, collecting trash, or

taking out garbage.

Use moist cleaning wipes to clean surfaces and things that you

touch, such as door handles, ATM or credit card keypads, and

any items that are used by other people.

Stay away from anyone with a fever, the flu, or other infection.

PRECAUTIONS TO PREVENT INFECTION DURING CANCER TREATMENT

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Do not wade, play, or swim in ponds, lakes, rivers, or water

parks.

Wear shoes all the time — in the hospital, outdoors, and at

home. This helps you avoid injury and keep germs off your

feet.

Do not keep fresh flowers or live plants in your bedroom.

Use hot water to clean your dishes.

CONT…

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Globally, almost 20% of cancers are related to infection agents.

Several viruses with oncogenic potential stimulate cell proliferation

and cause tumors and cancer in animals and humans. They act with

different mechanisms depending on different factors.

The tumor viruses with small genomes  integrate into host cell

chromosomal DNA and cause mutations and chromosomal

rearrangements that predispose to cancer. The oncogenic DNA and

RNA viruses that are carrying oncogenes encode transforming

proteins to stimulate tumor formation.

CONCLUSION

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1. Murat ŞEVİK, Laboratory of Molecular Microbiology,

Veterinary Control Institute, Konya – TURKEY, Oncogenic

viruses and mechanism of oncogenesis, 2012; 36(4): pg.

no.323-329.

2. Parkin, Donald Maxwell (2006). "The global health burden

of infection-associated cancers in the year 2002".

International Journal of Cancer, 118 (12): pg. no.3030–44.

3. Oncovirus, from wikipedia, the free encyclopedia.

REFERENCES

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