1. PRESENTATION
ON
ROLE OF VIRUSES IN CANCER
PRODUCTION
DURGESH SIROHI
(M.Sc Ist Sem.)
2. Cancer
Types of cancer
Sign & symptoms
Viruses & Cancer
Hepatitis B virus
Hepatitis C virus
Human papilloma virus
Epstein-Barr virus
Human T-Lymphotropic virus
Conclusion
3. Cancer known medically as a malignant
neoplasm, is a broad group of various
diseases, all involving unregulated cell
growth.
In cancer, cells divide and grow
uncontrollably, forming malignant tumors,
and invade nearby parts of the body.
The cancer may also spread to more distant
parts of the body through the lymphatic
system or blood streams.
4. The unregulated proliferation and loss of
differentiation results in invasive growth that
forms unorganised cell masses. This state is
called Anaplasia.
2 major type of tumors w.r.t growth pattern
are- BENIGN & MALIGNANT OR CANCEROUS
TUMORS.
Benign – here the tumor cells remain in place
to form a compact mass.
Malignant – here the tumors can actively
spread throughout the body.
5. Not all tumors are cancerous.
Benign tumors do not grow uncontrollably,
do not invade neighboring tissues, and do
not spread throughout the body.
A benign tumor is a tumor that lacks the
ability to metastasize.
The term "benign" implies a mild and non
progressive disease.
Common examples of benign tumors include
moles and uterine fibroids.
6.
7. certain cells suddenly abandon their normal growth
pattern and begin to reproduce uncontrollably –
they become cancerous.
As these cells multiply, they form a lump, or
primary tumor. From this tumor, cancer cells often
travel through the lymphatic system or the
bloodstream to other parts of the body, and form
tumor there as well.
This spreading and clumping of cancerous cells is
known as metastasis.
8. The main categories of cancer includes
Carcinoma - cancer that begins in the skin or in
tissues that line or cover internal organs.
Sarcoma - cancer that begins in bone, cartilage, fat,
muscle, blood vessels, or other connective or
supportive tissue.
Leukemia - cancer that starts in blood-forming tissue
such as the bone marrow and causes large numbers
of abnormal blood cells to be produced and enter the
blood.
Lymphoma and myeloma - cancers that begin in the
cells of the immune system.
Central nervous system cancers - cancers that begin
in the tissues of the brain and spinal cord.
10. Cancer symptoms are changes in the body
caused by the presence of cancer. They are
usually caused by the effect of a cancer on
the part of the body where it is growing,
although the disease can cause more general
symptoms such as weight loss or tiredness. It
is advisable that anyone experiencing unusual
symptoms that are not normal for them for
more than a few weeks should seek medical
attention.
11. The presence of an unusual lump in the body.
Changes in a mole on the skin.
A persistent cough or hoarseness.
A change in bowel habits, such as unusual
diarrhea or constipation.
Difficulty in swallowing or continuing indigestion.
Any abnormal bleeding, including bleeding from
the vagina, or blood in urine or faeces.
A persistent sore or ulcer.
Difficulty passing urine.
Skin changes such as an unexplained rash.
14. Viruses have played an essential role in cancer
biology research over the past several decades. At
first, viruses were utilized as valuable laboratory
research tools for understanding cell cycle controls
and carcinogenesis, the origins and development of
cancer. The use of viruses allowed researchers to
unreveal the genetics, mechanisms, and controls
governing the processes of normal cell growth and
differentiation. Viruses were also used to
determine the role of aberrant cell growth or
proliferation - processes characteristic of
cancerous tissues.
15. A virus that can cause cancer is called an
oncovirus.
Cancer-causing viruses function much as non-carcinogenic
viruses do, invading the living cells of
the host and using its DNA-synthesizing proteins
and mechanisms in order to produce more copies
of itself. Then, the virus disrupts an integral cell-cycle
control mechanism in order to render the
infected cell and its progeny cancerous, or "hyper-proliferative."
Uncontrolled cell replication or
proliferation is the basis for oncogenesis.
16. Some viruses can also play a role in converting
normal host cells into tumor cells. These viruses
are capable of viral transformation, that is, they
transform normal cells into malignant cells.
In fact, five viruses, hepatitis B virus (HBV),
hepatitis C virus (HCV), human papilloma virus
(HPV), Epstein-Barr virus (EBV), and human T-lymphotropic
virus type I (HTLV-I) are thought to
contribute to over 15% of the world's cancers. Up to
80% of these human viral-associated cancers are
cervical cancer (associated with HPV) and liver
cancer (associated with HBV and HCV).
17. Hepatitis B is an infectious inflammatory illness of
the liver caused by the hepatitis B virus (HBV) that
affects hominoidea, including humans. Originally
known as "serum hepatitis", the disease has caused
epidemics in parts of Asia and Africa, and it is
endemic in China. About a third of the world
population has been infected at one point in their
lives, including 350 million who are chronic
carriers.
Hepatitis B virus is an hepadnavirus—hepa from
hepatotropic (attracted to the liver) and dna
because it is a DNA virus—and it has a circular
genome of partially double-stranded DNA.
18. • Hepatitis B viruses cannot be spread by holding hands,
sharing eating utensils or drinking glasses, kissing, hugging,
coughing, sneezing, or breastfeeding.
• The virus is transmitted by exposure to infectious blood or
body fluids such as semen and vaginal fluids, while viral DNA
has been detected in the saliva, tears, and urine of chronic
carriers.
The acute illness causes liver inflammation, vomiting,
jaundice and, rarely death. Chronic hepatitis B may eventually
cause liver cancer.
The infection is preventable by vaccination.
19. Hepatitis C is an infectious disease affecting
primarily the liver, caused by the hepatitis C virus
(HCV).
The hepatitis C virus (HCV) is a small, enveloped,
single-stranded, positive-sense RNA virus.It is a
member of the hepacivirus genus in the family
Flaviviridae.
20. The infection is often asymptomatic, but
chronic infection can lead to scarring of the
liver and ultimately to cirrhosis, which is
generally apparent after many years. In
some cases, those with cirrhosis will go on
to develop liver failure, liver cancer .
HCV is spread primarily by blood-to-blood
contact associated with intravenous drug
use, poorly sterilized medical equipment
and transfusions.
21. Human papillomavirus (HPV) is a virus from the
papillomavirus family that is capable of infecting
humans.
Like all papillomaviruses, HPVs establish productive
infections only in keratinocytes of the skin or
mucous membranes.
HPV cause no symptoms in most people, some
types can cause warts (verrucae), while others can –
in a minority of cases – lead to cancers of the
cervix, vulva, vagina, penis, oropharynx and anus.
22.
23. HPV can cause normal cells on infected skin
to turn abnormal. Most of the time, we
cannot see or feel these cell changes. In most
cases, the body fights off HPV naturally and
the infected cells then go back to normal. But
in cases when the body does not fight off
HPV, HPV can cause visible changes in the
form of genital warts or cancer. Warts can
appear within weeks or months after getting
HPV. Cancer often takes years to develop
after getting HPV.
24. The Epstein–Barr virus (EBV), also called human
herpesvirus 4 (HHV-4), is a virus of the herpes
family, and is one of the most common viruses in
humans.
It is best known as the cause of infectious
mononucleosis (glandular fever). It is also
associated with particular forms of cancer, such as
Hodgkin's lymphoma, Burkitt's lymphoma,
nasopharyngeal carcinoma, and central nervous
system lymphomas associated with HIV. There is
evidence that infection with the virus is associated
with a higher risk of certain autoimmune diseases.
25. Infection with EBV occurs by the oral transfer of
saliva.
When infection with EBV occurs during adolescence
or teenage years, it causes infectious
mononucleosis 35 to 50 percent of the time.
26. EBV has been implicated in several diseases that
include
infectious mononucleosis
Burkitt's lymphoma
Hodgkin lymphoma
nasopharyngeal carcinoma
multiple sclerosis
27.
28.
29. Human T-cell Lymphotropic Virus or Human T-lymphotropic
virus Type 1 (HTLV-I), also called the
Adult T-cell lymphoma virus type 1, a virus that has
been implicated in several kinds of diseases including
HTLV-I-associated myelopathy, Strongyloides
stercoralis hyper-infection, and a virus cancer link for
leukemia. Between one in twenty and one in twenty-five
infected persons are thought to develop cancer as a
result of the virus.
It was the first identified human retrovirus.
Infection with HTLV-I, like infection with other
retroviruses, probably occurs for life and can be
inferred when antibodies against HTLV-1 are detected
in the serum.
30. Motor and sensory changes in the extremities
Spastic gait in combination with weakness of the
lower limbs
Clonus
Bladder dysfunction and bladder cancer
31. Transmission of HTLV-I is believed to occur by sexual
contact, from mother to child via breastfeeding, and through
exposure to contaminated blood, either through blood
transfusion or sharing of contaminated needles. The
importance of the various routes of transmission is believed
to vary geographically.
In Japan, the geographic clustering of infections suggest that
the virus is more dependent on mother-to-child
transmission.
In the Caribbean, the geographic distribution of the virus is
more uniform, and it is more common among those with
many sexual partners, indicating that sexual transmission is
more common.
32. Viruses are thought to play a role in cancer
development both indirectly and directly. Indirectly,
the viruses may induce immunosuppression so that
cancer cells are not removed by immune
responses, as in the case of HIV/AIDS, or they may
cause long term damage to tissues resulting in
large scale cell regeneration which increases the
chances of natural mutation in proto-oncogenes
and tumor suppressor genes, as in the case of HBV
and HCV. Directly, by integrating into the host
cell's chromosomes, some viruses may alter the
normal function of the proto-oncogenes and tumor
suppressor genes, as is seen with HPV and HBV.
33. However, most virus-associated cancers have
long latency periods of several decades and
only a small percentage of the people
infected with the virus actually develop the
cancer. This indicates other factors
promoting changes in cellular genes are also
involved.
