THIS IS THE DNA VIROLOGY

1. GEN CONCEPTS (Micro/Para)
Virology 1 (DNA viruses)
GRETCHEN G. AGDAMAG-CALDERON MD, DPBO

2. OBJECTIVES
• Understand the basic concepts in virology
• Differentiate RNA from DNA viruses
• Know the clinical features, diagnosis and
basic management of important DNA
viruses affecting human health

3. REFERENCES
• Levinson, Warren; Review of Medical
Microbiology and Immunology
(Lange Medical Books) 13th ed
• Riedel, Morse et al; Jawetz Melnick &
Adelbergs Medical Microbiology-
Lange 28th ed

4. vs

5. VIRUSES
• Obligate intracellular, potentially
pathogenic entities, possessing only
one type of nucleic acid either RNA
or DNA
• The extracellular infective form of
virus is called virion

7. DNA VIRUS
• Two classes
• Single-strand DNA viruses e.g.
parvovirus
• Double-strand DNA viruses
e.g.Polyomaviruses,
papillomaviruses, adenoviruses,
herpesviruses

11. POXVIRUS
• The largest viruses,
almost visible on light
microscopy (240x 300
nm) and are ovoid to
brick shaped with a
complex morphology

12. POXVIRUS
 dsDNA
 Brick shaped
 “dumbbell” core (contains nucleic
acid)
 Lateral bodies (unknown function)
 Enveloped, resistant to inactivation

13. POXVIRUS
 More than 100 polypeptides
 Many target the immune response
 Replicate in cytoplasm
 Tend to be highly species-specific
 Some are being explored as gene
therapy vectors
 Clinical syndromes include
smallpox and molluscom
contagiosum

14. POXVIRUS
CLINICAL SYNDROMES
 Smallpox - eradicated
 Named smallpox to discriminate it
from largepox (syphilis)
 Two species
 Variola major (20% fatality)
 Variola minor (1-2% fatality)
 Smallpox has shaped civilization
 Killed 300 million people in the 20th
century alone
 Vaccinia, a form of cowpox, was
used for the smallpox vaccine

15. POXVIRUS
CLINICAL SYNDROMES
 Smallpox

16. POXVIRUS
CLINICAL SYNDROMES
 Molluscum contagiosum

17. POXVIRUS
CLINICAL SYNDROMES
 Molluscum contagiosum
 lesions differ significantly from pox lesions
in being nodular to wartlike
 Begin as papules and then become
pearl-like, umbilicated nodules that
have a central caseous plug
 Incubation period for molluscum
contagiosum is 2 to 8 weeks, and the
disease is spread by direct contact
(e.g., sexual contact, wrestling) or
fomites (e.g., towels)

18. POXVIRUS
CLINICAL SYNDROMES
 Molluscum contagiosum
 Confirmed histologically by the finding of
characteristic large, eosinophilic cytoplasmic
inclusions (molluscum bodies) in epithelial
cells
 Lesions of molluscum contagiosum disappear
in 2 to 12 months, presumably as a result of
immune responses.
 Nodules can be removed by curettage
(scraping) or the application of liquid
nitrogen or iodine solutions

19. HERPESVIRUS
• Spherical icosahedron
• Double-stranded DNA,
linear
• Enveloped

20. HERPESVIRUS

21. HERPESVIRUS
• HSV1
• HSV2
• VZV
• CMV
• EBV
• HHV6
• HHV7
• HHV8 – Kaposi’s sarcoma

22. HERPESVIRUS
• latency and recurrent infections
• complications of latency and
recurrent infections become
more severe with age,
cancer chemotherapy etc
• most common and serious
opportunists among AIDS
patients

23. HERPESVIRUS
• CLINICAL SYNDROMES

24. HERPESVIRUS

25. HERPESVIRUS
• Varicella Zoster Virus (VZV)
 causes chickenpox & shingles
 primary infection – chickenpox –
vesicles
 virus enters neurons and remains latent
 later, reactivation of the virus results in
shingles with vesicles localized to
distinctive areas, dermatomes
 treatment : acyclovir, famciclovir,
interferon
 live attenuated vaccine

27. HERPESVIRUS
• CYTOMEGALOVIRUS
• produce giant cells with nuclear
and cytoplasmic inclusions
• transmitted in saliva, respiratory mucus,
milk, urine, semen, cervical secretions
and feces
• commonly latent in various tissues
• most infections are asymptomatic
• 3 groups develop a more virulent form
of disease: fetuses, newborns,
immunodeficient adults

28. HERPESVIRUS
• CYTOMEGALOVIRUS
• newborns may exhibit enlarged liver,
spleen, jaundice, capillary bleeding
microcephaly and ocular inflammation
• AIDS patients – CMV
mononucleosis, disseminated
CMV, retinitis
• transplant patients - pneumonitis,
hepatitis, myocarditis,
meningoencephalitis
• treatment: ganciclovir, valvcyclovir,
foscarnet

30. HERPESVIRUS
• EPSTEIN BARR VIRUS
• infects lymphoid tissue and salivary
glands
• mononucleosis – sore throat, high
fever, cervical lymphadenopathy
• Burkitt’s lymphoma associated
with chronic co infections
• nasopharyngeal carcinoma

31. HERPESVIRUS
• EPSTEIN BARR VIRUS

32. HERPESVIRUS
• EPSTEIN BARR VIRUS

33. HERPESVIRUS
HHV6
• transmitted by close contact
• very common
• causes roseola
• usually self limited
• adults may get monolike
symptoms,lymphadenopa
thy, hepatitis

34. HERPESVIRUS

35. HERPESVIRUS
 HHV7 is closely related to HHV6
causes similar diseases
 Kaposi’s sarcoma associated virus or HHV
8 is linked with common tumor of AIDS
patients, also may be involved in multiple
myeloma

36. HEPADNAVIRUS
 enveloped DNA viruses
 unusual genome
containing both double
and single stranded DNA
 tropism for liver
 Hepatitis B virus causes
hepatitis and can be a
factor in liver cancer

37. HEPADNAVIRUS
 VIRAL HEPATITIS
 Inflammatory disease of liver cells that
may result from several viruses
 interferes with liver’s excretion of bile
pigments, bilirubin accumulates in
blood and tissues causing jaundice

38. HEPADNAVIRUS
 VIRAL HEPATITIS

39. HEPADNAVIRUS
 HEPATITIS B VIRUS
 multiplies exclusively in the
liver, which continuously
seeds blood with viruses
 sexually transmitted
 high incidence among
homosexuals and illicit drug users
 can become a chronic infection
 increases risk of liver cancer

40. HEPADNAVIRUS
 HEPATITIS B VIRUS

41. HEPADNAVIRUS
 HEPATITIS B VIRUS
 chronic infection - controlled
with interferon
 HB immune globulin protects
exposed people
 HBV vaccine – recombinant
surface antigen made by
yeast; given in 3 doses over 18
months

42. PAPOVAVIRUS

43. PAPOVAVIRUS
 PAPILLOMA
 benign, squamous
epithelial growth,
wart
 caused by 40
different strains of
HPV
 transmissible through
direct contact or
contaminated
fomites

44. ADENOVIRUS
• medium sized,
non- enveloped,
double stranded
DNA viruses that
replicate and
produce disease
in the eye and in
the respiratory,
gastrointestinal
and urinary tracts

45. ADENOVIRUS
• Viruses primary infect children
• Adenoviruses 1-7 are the common
serotypes worldwide and are
responsible for most cases of
adenovirus-associated infections
• Incubation period varies from 5 to 8
days

46. ADENOVIRUS
Serotype Disease At risk
1-7 Acute febrile pharyngitis Children
3,7,14 Pharyngoconjunctival fever Older children
8,9,37 Epidemic keratoconjunctivitis
(shipyard eye)
Adults
3,4,11 Acute follicular conjunctivitis Any age
40,41 Diarrhoea Infants, young
children
11,21 Hemorrhagic cystitis Children

47. VIRUSES@!#?
https://www.youtube.com/watch?v=y8lXQ2tYwGM
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