Chapter 13 Infection agents and inflammation section
10-15% of human cancers is caused by infection agents (viruses)
2.2 million new cancer cases were attributable to infections in 2018 (13%)
4 most important infectious pathogens for cancer
o Helicobacter pylori
o High-risk human
papillomavirus (HPV)
o Hepatitis B (HBV)
o C viruses (HCV) – RNA virus –
associated with hepatocellular
carcinoma (liver cancer)
Other infectious pathogens for cancer
o Epstein-Barr virus (EBV)
o Human T-cell lymphotropic
virus type 1 (HTLV-1)
o Human herpesvirus type 8
(HHV8)
o Parasitic infections
Incidence of infections is higher in
developing countries – vaccination
and screen-and-treat programmes
will enable relatively fast reduction of the incidence of cancer
Productive infection vs transforming infection
2 types of infections:
1. Productive infection – in permissive cell – lytic life cycle (most
viruses take this pathway!)
SV40 virus infect permissive cell viral replication of genome
new viruses are formed cell lysis
2. Transforming infection – in non-permissive cell (less viruses take
this pathway)
SV40 virus infect non-permissive cell viral replication of genome
is blocked no new viruses are formed virus can transform
cells (e.g. in cancer cells)
In transformation usually only EARLY functions are expressed
Tumor viruses do not intend to transform their host cells
Virus make use of the hallmarks of cancer to maintain replication and
cause cancer
Non-HPV associated cancers
Epstein-Barr virus (EBV);
o DNA virus
o Associated with Burkitt’s lymphoma, nasopharyngeal carcinoma,
Hodgkin disease, other lymphomas and gastric cancer
o It encodes viral proteins (LMP1) that affect host gene expression. LMP1
is able to transform cells in culture
o Multi-functional effects include promoting cell proliferation and inhibiting
apoptosis
10-15% of human cancers is caused by infection agents (viruses)
2.2 million new cancer cases were attributable to infections in 2018 (13%)
4 most important infectious pathogens for cancer
o Helicobacter pylori
o High-risk human
papillomavirus (HPV)
o Hepatitis B (HBV)
o C viruses (HCV) – RNA virus –
associated with hepatocellular
carcinoma (liver cancer)
Other infectious pathogens for cancer
o Epstein-Barr virus (EBV)
o Human T-cell lymphotropic
virus type 1 (HTLV-1)
o Human herpesvirus type 8
(HHV8)
o Parasitic infections
Incidence of infections is higher in
developing countries – vaccination
and screen-and-treat programmes
will enable relatively fast reduction of the incidence of cancer
Productive infection vs transforming infection
2 types of infections:
1. Productive infection – in permissive cell – lytic life cycle (most
viruses take this pathway!)
SV40 virus infect permissive cell viral replication of genome
new viruses are formed cell lysis
2. Transforming infection – in non-permissive cell (less viruses take
this pathway)
SV40 virus infect non-permissive cell viral replication of genome
is blocked no new viruses are formed virus can transform
cells (e.g. in cancer cells)
In transformation usually only EARLY functions are expressed
Tumor viruses do not intend to transform their host cells
Virus make use of the hallmarks of cancer to maintain replication and
cause cancer
Non-HPV associated cancers
Epstein-Barr virus (EBV);
o DNA virus
o Associated with Burkitt’s lymphoma, nasopharyngeal carcinoma,
Hodgkin disease, other lymphomas and gastric cancer
o It encodes viral proteins (LMP1) that affect host gene expression. LMP1
is able to transform cells in culture
o Multi-functional effects include promoting cell proliferation and inhibiting
apoptosis
