fundamentals of virology notes for health care workers studying virology.

1. Hml 800: fundamentals of
Hml 800: fundamentals of
Virology

6. • Not all viruses make us
sick!

8. In animals ????

9. What is a virus?

10. Are viruses alive?
Are viruses alive?

13. Viruses are small
Smallest ~20nm, largest ~ 800nm

14. Giant viruses
Mimiviruses 750-800nm Pandoravirus 1000nm

16. History of virology

17. The Year 1193 BC
The Pharaoh Siptah rules Egypt from 1200-1193 BC
when he dies suddenly at the age of about 20.
His mummified body lays undisturbed in his tomb in
the Valley of the Kings until 1905 when the tomb
was excavated.
was excavated.
The mummy shows that his left leg was withered
and his foot was rigidly extended like a horse's
hoof - classic paralytic poliomyelitis
.
FOOT

18. The Year 1143 BC
Ramesses V's preserved mummy shows
that he died of smallpox at about the
age of 35 in 1143 BC.
The pustular lesions on the face of the mummy
are very similar to those of more recent
are very similar to those of more recent
patients . However, his head also displays a
major wound inflicted either before or shortly
after death.

20. Edward Jenner Vaccinating James Phipps, 1796

21. Edward Jenner vaccinating his son, who is held
by his wife

22. Microscope – Robert Hooke 1665

24. It started with Tobacco
Tobacco mosaic disease

27. Founders of virology
FMD caused by a small microbe - virus

28. First human virus 1900
Yellow fever virus by Walter Reed

29. Discovery of avian leukemia viruses (the first
leukemia virus)

30. 1911:Discovery of Rous sarcoma virus (1st solid tumor virus)
Cause cancer in chicken

31. This led to the designation of RSV as the first known tumor virus
and to the recognition of a new paradigm in cancer research

32. Viruses infect bacteria – bacteriophages
(Bacteria eaters) 1915-17

33. Purification and crystallization of Tobacco
mosaic virus 1935
Made of proteins TMV

34. Development of embryonating hen’s eggs
as host for viruses – to grow viruses

35. Development of cell culture methodology for
polio, measles 1949

36. Proof of DNA as the genetic material 1952

37. Discovery of the structure of DNA

38. The Year 1963
Baruch Blumberg discovers hepatitis B virus (HBV). (Nobel
Prize, 1976) Blumberg went on to develop the first vaccine
against the HBV, considered by some to be the first vaccine
against cancer because of the strong association of hepatitis B
with liver cancer.

39. Disputing the central dogma - discovery of the
reverse transcriptase of retroviruses 1970

40. First Human Retrovirus
Human T-lymphotropic virus (HTLV-I) 1980

41. Discovery of prions – the etiologic agents of the
spongiform encephalopathies - 1982

42. Discovery of Human immunodeficiency virus
(HIV) 1983

43. Recently……..
2007: Human polyomaviruses KI, WU, MC (Merkel carcinoma)
2012: Middle East respiratory syndrome-Coronavirus (MERS-CoV)
2015: Human hepegivirus 1 (HHpgV-1)

44. 1917, Robert Montgomery described a tick-borne gastro-
enteritis of sheep and goats, which was eventually named
Nairobi sheep disease while working at KARI-Kabete
History of Virology – Kenyan contribution

45. 1921, Robert Montgomery, African swine fever virus – It
is the only DNA Arbovirus

46. Isolation of Rift Valley fever virus from an outbreak in
Naivasha 1930

47. Development of a Rinderpest vaccine- Muguga

48. Review questions
• Explain the three theories of the origin of viruses
• Describe the experiments conducted by Dmitri Ivanovsky, and
Martinus Beijerinck and Friedrich Loeffler & Paul Frosch in
identifying viruses. Explain why Loeffler & Frosch are considered
the fathers of virology and not Ivanovsky and Beijerinck who had
conducted earlier experiments?
conducted earlier experiments?
• Viruses are a part of the biosphere. However, there is active debate
concerning whether they should be treated as living or nonliving.
(a) Briefly describe one feature of viruses that is also found in cell-
based life forms.
(b) Briefly describe one feature of viruses that distinguishes them
from cell-based life forms.