POXVIRUSES.ppt

Largest viruses that infect vertebrates
Can be seen under light microscope
Poxvirus diseases are characterized by skin lesions – localized or generalized
Important diseases caused by poxviruses are-
Smallpox
Monkeypox
Cowpox
Tanapox
Molluscum contagiosum

1. POXVIRUSES

2. Introduction
Largest viruses that infect vertebrates
Can be seen under light microscope
Poxvirus diseases are characterized by skin lesions –
localized or generalized
Important diseases caused by poxviruses are-
Smallpox
Monkeypox
Cowpox
Tanapox
Molluscumcontagiosum

3. Morphology
Poxviruses are brick shaped
Largest animal viruses & can be seen under
light microscope
In vertical section poxviruses have a biconcave
double stranded DNA core surrounded by a
double layered membrane
Envelope is the outermost layer & surrounds
the outer membrane

5. Resistance
May remain viable for months at room temp.
Survive for years in freeze dried form
They are susceptible to UV light & are
Resistant to 1% phenol but readily inactivated
by formalin
Though poxviruses are enveloped, they are not
inactivated by ether

6. Antigenic Structure
All poxviruses share a common nucleoprotein
(NP) antigen
Other antigens include –
•LS antigen -a complex of the heat labile (L)
and the heat stable (S) antigens
•Agglutinogen
•Haemagglutinin

7. Cultivation
They grow in chorioallantoic membrane
(CAM)of chick embryo and in tissue culture
Variola and vaccinia viruses produce pocks on
the CAM in 48-72 hours
Variola pocks are small, shiny ,white, convex,
non-necrotic & non-hemorrhagic
Vaccinia pocks are larger, irregular, grayish,
flat, necrotic & sometimes hemorrhagic

8. Cultivation………
Tissue culture of monkey kidneys
HeLa & chick embryo cells can be used
Cytopathic effects are produced by vaccinia in
24-48hrs but variola takes longer time to
produce these changes
Eosinophilic inclusion bodies (Guarnieri
bodies)can be seen in stained preparations

9. Diseases caused by Pox Viruses
Small Pox
Vaccinia
Monkeypox
Cow Pox
Milker’s Node
Molluscum Contagiosum

10. Difference Between Small Pox & Chicken Pox

11. Small Pox
An infectious disease unique to humans, caused by
either of two virus variants, Variola majorand
Variola minor.
localizes in small blood vessels of the skin and in
the mouth and throat.
in the skin, this results in a characteristic
maculopapular rash, and later, raised fluid-filled
blisters. V. majorproduces a more serious disease
and has an overall mortality rate of 30–35%. V.
minorcauses a milder form of disease

12. SMALL POX…….
Variola majorlast natural
case detected in 24
th
May 1975
Variola minorlast case
occurred in Somalia, in
October 1977
On 8
th
May 1980 WHO
formally announced the global
eradication of smallpox

13. Eradication achieved because of -
No sub-clinical infection or carrier state
An effective vaccine –originally discovered
by Jenner in 1796
No animal reservoir
Aggressive surveillance-containment measures
Two laboratories still hold the stock of variola
virus –WHO Collaboration Centre in Atlanta,
USA & Koltsovo, Russian Federation

14. Vaccinia of Knee

15. Cow Pox Of the upper Arm

16. Cow Pox of the Udder

17. Haemmorrghic Small Pox

18. VACCINIA VIRUS
Vcciniavirus was used for small pox
vaccination
It may have evolved from cowpox or smallpox
virus
It causes a localized skin infection
Employed as a vector for the development of
recombinant vaccines

19. Prophylaxis of Smallpox
Both variola& vacciniaviruses can be grown
on CAM of chick embryo
Vaccination with vacciniainduces protection
against smallpox for about five years
Natural infection of smallpox gives complete
protection against re-infection

20. Cowpox
Produces ulcers on the teats & udders
Human infection acquired by the process of
milking
Localized lesions on the hands of man
Undergo changes from macules to pustules
Rodents are the reservoir hosts of cowpox
virus

21. Human Monkeypox
Infection acquired by handling infected
animals
Resembles mild smallpox

22. Human MonkeyPox
Monkey pox-is a rare smallpox like disease
of children in central Africa. It is acquired
from monkeys but does occasionally spread
from man to man in unvaccinated
communities. Antigenicallyit cross-reacts
with other poxviruses.

23. MONKEY POX

24. Orf
It is a contagious pustular dermatitis of sheep
& goats
In man , disease occurs as a single lesion on
finger or hand or occasionally on the face

25. ORF
ORF-a worldwide occupational disease
associated with handling sheep and goats
afflicted ". In humans it manifests as a single
painless, papulo-vesicular lesion on the hand,
forearm or face.

26. Bulla Caused by orf virus infection

27. Milker Node
Pseudocowpox-occurs worldwide and is a
disease primarily of cattle. In humans it
causes non-ulcerating "milker's nodes".

28. Milker Nodule of Hand

29. Molluscum contagiosum
It is a benign epidermal tumour-like lesion
It mainly involves the arms, legs, buttocks &
genital area
It is a contagious disease
Virus is also transmitted sexually in adults
Nodules show hyaline acidophilic inclusion
bodies (molluscum bodies) within the
proliferated epidermal cells

30. Molluscum Contagiusm of Face

31. Molluscum Contagisum of Penis

32. Molluscum Contagiusm of Labia

33. Prophylaxis
Vaccination with vaccinia induces protection
against small pox .