TYPES OF VIRUSES IN HUMANS MODE OF VIRAL REPLICATION IN HUMANS HUMAN VIRAL DISEASES

1. HUMAN
VIRAL
DISEASES

2. CONTENTS
• INTRODUCTION
• TYPES OF VIRUSES IN HUMANS
• MODE OF VIRAL REPLICATION IN HUMANS
• HUMAN VIRAL DISEASES

3. INTRODUCTION
• Viruses are very tiny organisms and exist
almost everywhere, such as in the air, soil and
living organisms like humans
• Human body also harbours a lot of viruses,
but most of them do not cause diseases
• Human immune system can generate
antibodies against viruses; the antibody will
recognize the virus and destroy it

4. INTRODUCTION
• When the human immune system is weak the
viruses can overcome immune system and
cause problems, became so called opportunist
pathogen
• some viruses can cause serious diseases,
including AIDS, SARS, Hepatitis etc
• They use the host's system for replication and
gene expression

5. TYPES OF HUMAN VIRUSES
Viruses have two main types:
• DNA viruses
DNA is the genetic material of DNA virus
• RNA viruses
RNA is the genetic material of a RNA virus

6. DNA VIRUSES
• HERPESVIRIDAE
• ADENOVIRIDAE
• PAPILLOMAVIRIDAE
• POXVIRIDAE
• ANELLOVIRIDAE
• PARVOVIRIDAE

7. ds DNA VIRUSES
HERPESVIRIDAE
This family contains many viruses
which are enveloped, spherical
and have icosahedral symmetry,
few of them are:
• Simplexvirus
• Human herpesvirus 1 &
Human herpesvirus 2
• Varicellovirus
• Human herpesvirus 3
(Varicella-zoster virus)

8. ds DNA VIRUSES
• ADENOVIRIDAE
This family contains
viruses that are non-
enveloped and have
icosahedral
symmetry, these are:
• Mastadenovirus
• Human
adenoviruses

9. ds DNA VIRUSES
• PAPILLOMAVIRIDAE
This family contains many
viruses that are non-
enveloped and have
icosahedral symmetry, few of
them are:
• Alphapapillomavirus
– Human papillomaviruses
32
• Betapapillomavirus
– Human papillomavirus 5
(HPV-5)

10. ds DNA VIRUSES
• POXVIRIDAE
This family contains
viruses that are enveloped
and brick shaped, these
are:
• Orthopoxvirus
– Vaccinia virus, Variola
virus

11. ss DNA VIRUSES
• ANELLOVIRIDAE
This family contain viruses that
are non-enveloped and have
icosahedral symmetry, these
are:
• Alphatorquevirus
– Torque teno virus 1

12. ss DNA VIRUSES
• PARVOVIRIDAE
This family contains viruses
that are non-enveloped, these
are:
• Erythrovirus
– Human parvovirus B19

13. RNA VIRUSES
• REOVIRIDAE • FLAVIVIRIDAE
• PICORNAVIRIDAE
• TOGAVIRIDAE
• RHABDOVIRIDAE
• FILOVIRIDAE
• PARAMYXOVIRIDAE

14. ds RNA VIRUSES
• REOVIRIDAE
This family contains viruses
that are non-enveloped and
have icosahedral symmetry,
these are:
• Rotavirus
– Rotavirus A
• Seadornavirus
– Banna virus

15. ss RNA (+) VIRUSES
• viruses whose genetic information consists of
a single strand of RNA that is
the positive (or sense) strand.

16. ss RNA (+) VIRUSES
• FLAVIVIRIDAE
This family contains viruses
that are enveloped, spherical
and have icosahedral
symmetry, these are:
• Flavivirus
– Yellow fever virus
• Hepacivirus
– Hepatitis C virus (HCV)

17. ss RNA (+) VIRUSES
• PICORNAVIRIDAE
This family contains viruses that
are non-enveloped, spherical and
have icosahedral symmetry, these
are:
• Enterovirus
– Poliovirus
• Hepatovirus
– Hepatitis A virus (HAV)

18. ss RNA (+) VIRUSES
• TOGAVIRIDAE
This family contains
viruses that are
enveloped, spherical and
have icosahedral
symmetry, these are:
• Rubivirus
– Rubella viruses (RUBV)

19. Ss rna (-) VIRUSES
• Viruses whose genetic information consists of
a single strand of RNA that is the negative or
antisense strand.

20. SS RNA (-) VIRUSES
• RHABDOVIRIDAE
This family contains
viruses that are enveloped
and bullet shaped, these
are:
• Lyssavirus
– Rabies viruses

21. SS RNA (-) VIRUSES
• FILOVIRIDAE
This family contains viruses that
are filamentous in shape, these
are:
• Ebolavirus
– Zaire ebolavirus
– Reston ebolavirus
– Sudan ebolavirus

22. SS RNA (-) VIRUSES
• PARAMYXOVIRIDAE
• This family contains viruses
that are enveloped and
spherical, these are:
• Morbilivirus
– Measles virus
• Rubulavirus
– Mumps virus
• Pneumovirus
– Human respiratory
syncytial virus

23. SS RNA (-) VIRUSES
• ORTHOMYXOVIRIDAE
• This family contains viruses
that are enveloped, these
are:
• Influenzavirus A
– Influenzavirus A
• Influenzavirus B
– Influenza B virus
• Influenzavirus C
– Influenza C virus

24. RETROVIRUSES
• Lentivirus
• Human immunodeficiency
virus 1
• Orthohepadnavirus
• Hepatitis B virus (HBV)
The viruses which contains a single stranded RNA genome
and are non-enveloped and have icosahedral symmetry.

25. MODE OF VIRAL REPLICATION IN
HUMANS
• STEPS INVOLVE
Attachment
Penetration
Uncoating
Gene expression and genome replication
Assembly and release

26. ATTACHMENT
• Attachment to the cell surface
• Viral attachment protein recognizes specific receptors, which
may be protein, carbohydrate or lipid, on the outside of the
human cell
• Some viruses may require coreceptors which facilitates its
binding with a receptor on a cell
• For example, HIV virus recognize CD4 receptors on T cells
and chemokines as coreceptors

27. ATTACHMENT

28. PENETRATION
• ENVELOPED VIRUSES
BY FUSING WITH THE PLASMA MEMBRANE
• Viruses fuse directly with the plasma
membrane.
• Genome directly releases into the
cytoplasm of the cell

29. PENETRATION
• THROUGH ENDOSOMES AT THE CELL SURFACE
• Some enveloped viruses require an acid PH for
fusion to occur
• Are unable to fuse directly with the plasma
membrane
• Are taken up by invagination of the membrane
into endosomes

30. PENETRATION BY ENDOCYTOSIS OR
FUSION

31. PENETRATION
• NON-ENVELOPED VIRUSES
• Non-enveloped viruses may cross the plasma
membrane
Taken up into endosomes by endocytosis

32. UNCOATING
• Acidic pH of endosome
 Activates virus proteins that helps in fusion of the virion
membrane with the endosome membrane
 Release of viral genome into the cytoplasm of the cell
 This is known as "uncoating“
• DNA viruses must be targeted to the nucleus
• Entire nucleocapsid enters the nucleus, where uncoating
then takes

33. GENE EXPRESSION AND GENOME
REPLICATION
• Replication- Multiplication of the genome
• Replication involves
 Synthesis of viral messenger mRNA from "early" genes,
viral protein synthesis
 Possible assembly of viral proteins
 Viral genome replication mediated by early or regulatory
protein expression
 Further "late" gene expression of structural or virion
proteins.

34. ASSEMBLY AND RELEASE
• The structure-mediated self-assembly of the virus
particles
• Then viruses can be released from the host cell by
 Lysis
 Enveloped viruses- released by budding.
• During this process the virus acquires its envelope

35. RELEASE BY BUDDING

36. HUMAN VIRAL DISEASE
• All humans contract multiple viruses through out the
course of life
• Human diseases caused by viruses include
 chickenpox, HIV, influenza, Ebola, hepatitis, rabies,
cold sores and the common cold.

37. INFLUENZA
• The acute viral infection of respiratory tract
• Virus contains
 Single stranded RNA
 Pleomorphic appearance
 Diameter range between 80 to 120 nanometres.

38. SYMPTOMS OF INFLUENZA VIRUS
• Symptoms starts quite one to two days after
infection and includes
 First symptoms is chill and fever with body
temperature 38 to 39°C
 Pain through out their body
 Cough , sneezing, body aches, watering eyes
 Reddened eyes, skin, mouth throat

39. TRANSMISSION
• Influenza can spread in three main ways
 By direct transmission
 The airborne route and through hand to eye, hand to
nose, hand to mouth transmission
 Either from contaminated surface or from direct
personal contact such as hand shake

40. RABIES
• Rabies is a viral disease causes
 acute inflammation of the brain in humans

41. SYMPTOMS
• Early symptoms include
 Fever and tingling at the site of exposure
 Violent movement, uncontrolled excitement, fear,
confusion, and loss of conciousness
 Once symptoms appear always result in death

42. TRANSMISSION
• Rabies spread when
 An infected animals scratches or bite another animal
and human.
 Saliva from an infected animals
 Infected bats, monkey, foxes, cattle are vector of
rabies virus

43. HEPATITIS B
• Hepatitis B is an infectious disease caused by
the hepatitis B virus which affect the liver

44. SYMPTOMS
• It may take 30 to 150 days for symptoms that
includes
 Sickness with vomiting, yellow skin, feeling tired,
dark urine and abdominal pain
 Most of those with chronic disease have no
symptoms however cirrhosis and liver cancer may
develop

45. TRANSMISSION
• Transmission of hepatitis B virus result from
 Exposure to infectious blood or body fluids
containing blood
 Re-use of contaminated needles and syringes
 Mother to child