Module Virology Part 2 (DNA)

Question 1

What is the defining shape and symmetry of Herpesviridae?
Herpesviridae (“creeping”)

Answer 1

Enveloped DNA viruses with icosahedral symmetry.

Question 2

Where does Herpesviridae replicate and what inclusion bodies do they form?

Answer 2

Replicate in the nucleus and form intranuclear inclusion bodies.

Question 3

What is the size range of Herpesviridae?

Answer 3

120–200 nm in diameter

Question 4

What common outcome occurs after infection with Herpesviridae?

Answer 4

Latency

Question 5

How many viruses are included in the Herpesviridae family and what hosts do they infect?

Answer 5

More than 100 viruses infecting humans, birds, mammals, fish, amphibians, and reptiles

Question 6

Enumerate the three subfamilies of veterinary importance under Herpesviridae and their general disease systems affected.

Answer 6

Alphaherpesvirinae

Betaherpesvirinae

Gammaherpesvirinae
- Cause diseases of the respiratory, reproductive, and nervous systems.

Question 7

Enumerate the three bovine herpesviruses and their characteristics.

Answer 7

Bovine herpesvirus 1 (Varicellovirus): Causes respiratory (IBR) and genital (IPV, balanoposthitis) infections; occurs worldwide.

Bovine herpesvirus 2 (Simplexvirus): Causes ulcerative mammilitis and pseudo-lumpy disease (temperate vs tropical regions).

Bovine herpesvirus 5 (Varicellovirus): Causes encephalitis in calves.

Question 8

DNA Viruses
1- Herpesviridae: creeping

Answer 8

General characters:
1. Enveloped DNA viruses with icosahedral symmetry.
2. Replicate in nucleus, with intranuclear inclusion bodies.
3. 120-200 nm in diameter.
4. Latency is a common outcome of infection with these
viruses.
5. This family contains more than 100 viruses which cause
different diseases in human, birds, mammals, fish, amphibian
&reptiles.

Question 9

2- Poxviridae
General characters:

Answer 9

General characters:
1. Largest viruses (220-450 nm x 140- 260 nm).
2. Complex symmetry, brick shaped viruses.
3. Enveloped DNA viruses replicate in cytoplasm.
4. Virions are stable at room temperature under dry
conditions, but sensitive to heat, detergents, formaldehyde
and oxidizing agents.
5. Skin lesions prominent feature.
6. Genetic recombination within genera results in extensive
serological cross reaction and cross- protection

Question 10

3- Adenoviridae
Gland

Answer 10

General characters:
1. Non enveloped, double-stranded DNA viruses.
2. Icosahedral symmetry, 70-90 nm in diameter.
3. Replicate in nuclei, forming intranuclear inclusion bodies.
4. Fibers project from twelve vertices of capsid.
5. Agglutinate rat or monkey RBCs
6. Resist freezing, mild acid & lipid solvents, 56C for 10 min.
7. Moderately stable in the environment
-Systemic and respiratory diseases in dogs
-Systemic diseases in poultry

Question 11

4- Parvoviridae
small
General characters:

Answer 11

General characters:
1. small (18-26 nm), non enveloped DNA viruses.
2. Icosahedral symmetry, single stranded DNA.
3. Replicate in the nucleus forming intranuclear inclusion
bodies.
4. Require rapidly- dividing cells for replication.
5. Resistant to heat 56C for more than 60 minutes also
resistant to lipid solvents, disinfectants, pH (3-9) changes.
6. Inactivated by formalin, â - Propiolacton, sodium
hypochlorite

Question 12

5-Papillomaviridae
General characters:

Answer 12

1. Non-enveloped, circular double strand DNA viruses.
2. Icosahedral symmetry, 55 nm in diameter.
3. Replications in nucleus
4. Resistant to lipid- solvents, acids, 60°C for 30
   minutes.

Question 13

6- Circoviridae
General characters:

Answer 13

General characters:
1. small (17- 22 nm in diameter), non-enveloped.
2. Circular single stranded DNA, Icosahedral symmetry.
3. Stable at pH 3-9, heating at 60 °C for 30 minutes.
4. Causes infections in chickens, pigs and plants

Question 14

7- Asfarviridae: African Swine Fever
General characters:

Answer 14

General characters:
1. Enveloped DNA viruses, 175-215 nm in diameter.
2. Icosahedral symmetry.
3. Replicate in cytoplasm of host cells & in soft ticks of the
Ornithodorus species
4. Stable at 4-20 °C, persist for months in meat.
5. Only one genus which Asfavirus/Asfivirus causing African
Swine Fever.

Question 15

Among DNA viruses, which family is known as “creeping viruses” and why are they called so?

Answer 15

Herpesviridae — called “creeping” because of their tendency to produce recurrent and latent infections that reappear (“creep back”) after initial recovery.

Question 16

Identify the structural features of Herpesviridae.

Answer 16

They are enveloped DNA viruses with icosahedral symmetry.

Question 17

Where does Herpesviridae replicate and what inclusion bodies do they form?

Answer 17

Replicate in the nucleus and form intranuclear inclusion bodies.

Question 18

How many viruses does the Herpesviridae family contain and in which species do they cause diseases?

Answer 18

It contains more than 100 viruses causing diseases in humans, birds, mammals, fish, amphibians, and reptiles.

Question 19

Enumerate the three subfamilies of veterinary importance under Herpesviridae.

Answer 19

1. Alphaherpesvirinae
2. Betaherpesvirinae
3. Gammaherpesvirinae

Question 20

: Give examples of herpes infections in ruminants caused by Alphaherpesvirinae.

Answer 20

Answer:
a. Bovine herpesvirus 1 (BHV-1) — causes Infectious bovine rhinotracheitis (IBR) and Infectious pustular vulvovaginitis.
b. Bovine herpesvirus 2 — causes Ulcerative mammilitis (temperate regions) and Pseudo-lumpy skin disease (tropical/subtropical).
c. Bovine herpesvirus 5 — causes Encephalitis in calves.

Question 21

Question: What are the herpesvirus infections affecting poultry

Answer 21

Answer:

Infectious laryngotracheitis (ILT)

Marek’s disease

Duck plague (duck viral enteritis)

Question 22

Question: What are common human diseases caused by Herpesviruses?

Answer 22

Herpes simplex type 1 — causes Fever blisters.

Varicella-zoster virus — causes Chicken pox and Shingles.

Question 23

Identify the genus and main features of Bovine herpesvirus 1.

Answer 23

Genus: Varicellovirus

Comments: Causes Respiratory (IBR) and Genital (Infectious pustular vulvovaginitis and balanoposthitis) infections. Occurs worldwide.

Question 24

Question: Identify the genus and comments for Bovine herpesvirus 2.

Answer 24

Answer:

Genus: Simplexvirus

Comments: Causes Ulcerative mammilitis in temperate regions and Pseudo-lumpy disease in tropical/subtropical regions.

Question 25

What disease does Bovine herpesvirus 5 cause?

Answer 25

Encephalitis in calves.

Question 26

Identify the two ruminant herpesviruses under the genus Rhadinovirus and their significance.

Answer 26

Ovine herpesvirus 2: Causes subclinical infection in sheep and goats worldwide; causes malignant catarrhal fever (MCF) in cattle and wild ruminants. Alcelaphine herpesvirus 1: Causes subclinical infection in wildebeest (Africa and zoos); causes malignant catarrhal fever in cattle, deer, and other ruminants.

Question 27

Enumerate the equine herpesviruses and their respective diseases.

Answer 27

Equine herpesvirus 1 (Varicellovirus): Causes abortion, respiratory diseases, neonatal infection, and neurological disease. Occurs worldwide. Equine herpesvirus 3 (Varicellovirus): Causes mild venereal infection in mares and stallions. Equine herpesvirus 4 (Varicellovirus): Causes rhinopneumonitis in young horses and sporadic abortion. Occurs worldwide.

Question 28

Question: Give the herpesvirus diseases in domestic carnivores.

Answer 28

Canine herpesvirus 1 (Varicellovirus): Causes fatal generalized infection in neonatal pups. Feline herpesvirus 1 (Varicellovirus): Causes feline viral rhinotracheitis in young cats

Question 29

Identify the two porcine herpesviruses and their diseases.

Answer 29

Porcine herpesvirus 1 (Aujeszky’s disease virus) — Varicellovirus; causes Aujeszky’s disease (pseudorabies). Porcine herpesvirus 2 (unassigned) — causes disease of upper respiratory tract in young pigs (inclusion body rhinitis).

Question 30

Enumerate the herpesvirus infections in birds and describe their features

Answer 30

Gallid herpesvirus 1 (Infectious laryngotracheitis-like virus): Causes Infectious laryngotracheitis. Present in many countries. Gallid herpesvirus 2 (Marek’s disease virus): Causes Marek’s disease, a lymphoproliferative disease in 12–24-week-old chickens. Occurs worldwide. Anatid herpesvirus 1 (An-HV1): Causes acute disease in ducks, geese, and swans characterized by oculonasal discharge, diarrhea, and high mortality. Occurs worldwide.

Question 31

Which virus family includes the largest DNA viruses, and what are their dimensions?

Answer 31

Answer: Poxviridae; 220–450 nm × 140–260 nm

Question 32

Question: Describe the symmetry and shape of Poxviridae virions.

Answer 32

Complex symmetry and brick-shaped

Question 33

Where does Poxviridae replicate within the host cell?

Answer 33

In the cytoplasm.

Question 34

What are the environmental sensitivities and stabilities of Poxviridae?

Answer 34

Stable: At room temperature under dry conditions. Sensitive: To heat, detergents, formaldehyde, and oxidizing agents.

Question 35

What is the most prominent feature of diseases caused by Poxviridae?

Answer 35

Answer: Skin lesions

Question 36

What does genetic recombination within genera of Poxviridae lead to?

Answer 36

Extensive serological cross-reaction and cross-protection.

Question 37

Enumerate the two subfamilies of Poxviridae.

Answer 37

Answer: 1. Chordopoxvirinae 2. Entomopoxvirinae

Question 38

Enumerate the genera of Poxviridae and give examples for each.

Answer 38

a. Orthopoxvirus: Vaccinia virus, Cowpox virus, Variola virus. b. Parapoxvirus: Orf virus, Bovine papular stomatitis virus, Pseudocowpox virus. c. Capripoxvirus: Goat pox virus, Sheep pox virus, Lumpy skin disease virus. d. Avipoxvirus: Fowl pox virus, Pigeon pox virus, Turkey pox virus. e. Suipoxvirus: Swinepox virus. f. Leporipoxvirus: Myxoma virus (in rabbits). g. Entomopoxvirus: Infects insects

Question 39

Identify the viral family described as non-enveloped, double-stranded DNA viruses with icosahedral symmetry measuring 70–90 nm in diameter.

Answer 39

Adenoviridae

Question 40

Where do Adenoviridae replicate, and what type of inclusion bodies do they form?

Answer 40

Replicate in the nucleus, forming intranuclear inclusion bodies.

Question 41

What unique structural feature projects from the twelve vertices of the Adenoviridae capsid?

Answer 41

Fibers project from the twelve vertices of the capsid.

Question 42

Question: What kind of red blood cells can Adenoviruses agglutinate?

Answer 42

Rat or monkey RBCs

Question 43

Enumerate the physical resistances of Adenoviridae.

Answer 43

Answer: Resist freezing Resist mild acid Resist lipid solvents Resist 56°C for 10 minutes Moderately stable in the environment

Question 44

What types of diseases does Adenoviridae cause in animals?

Answer 44

Answer: Systemic and respiratory diseases in dogs Systemic diseases in poultry

Question 45

Enumerate the genera of Adenoviridae and the diseases they cause.

Answer 45

1. Aviadenovirus: Causes Hydropericardium hepatitis syndrome (HHS) and Egg drop syndrome in layers. 2. Mastadenovirus: Mammalian adenoviruses causing infectious canine hepatitis in dogs and pulmonary infections in equine (fatal in Arabian foals).

Question 46

Identify the viral family described as small (18–26 nm), non-enveloped, single-stranded DNA viruses that replicate in the nucleus.

Answer 46

Parvoviridae

Question 47

Enumerate the general characteristics of Parvoviridae.

Answer 47

1. Small (18–26 nm) 2. Non-enveloped DNA viruses 3. Icosahedral symmetry 4. Single-stranded DNA 5. Replicate in the nucleus, forming intranuclear inclusion bodies 6. Require rapidly dividing cells for replication 7. Resistant to: Heat (56°C for >60 min) Lipid solvents Disinfectants pH changes (3–9) 8. Inactivated by: Formalin, β-Propiolactone, and Sodium hypochlorite

Question 48

Enumerate the subfamilies of Parvoviridae and the species they infect.

Answer 48

Answer: Parvovirinae: Infect mammalian species Densovirinae: Infect arthropods

Question 49

Enumerate the genera of Parvoviridae with their diseases.

Answer 49

1. Parvovirus: Causes enteric and systemic disease in dogs and cats (Feline panleukopenia / Feline infectious enteritis) Causes reproductive failure (SMEDI syndrome) in pigs Shed in large numbers in feces 2. Erythrovirus: Human parvovirus B19 causes erythema infectiosum (fifth disease) in children 3. Dependovirus: Dependent on adenoviruses for replication

Question 50

Enumerate key features of viruses in the genus Parvovirus.

Answer 50

Answer: Many have haemagglutinating activity Shed in large numbers in feces Cause enteric and systemic diseases in dogs and cats Cause reproductive failure (SMEDI syndrome) in pigs

Question 51

Identify the viral family that is non-enveloped, circular double-stranded DNA, 55 nm in diameter, and replicates in the nucleus.

Answer 51

Papillomaviridae

Question 52

How many genera are present in Papillomaviridae and what are their characteristics?

Answer 52

Answer: One genus: Papillomavirus a. Have not been cultured in vitro b. Cause papillomas and fibropapillomas in domestic animals c. Bovine papilloma virus types 1 and 2 are aetiologically involved in equine sarcoids

Question 53

Identify the viral family described as small (17–22 nm), non-enveloped, circular single-stranded DNA viruses with icosahedral symmetry.

Answer 53

Circoviridae

Question 54

Enumerate the general characteristics of Circoviridae.

Answer 54

Answer: 1. Small (17–22 nm in diameter) 2. Non-enveloped 3. Circular single-stranded DNA 4. Icosahedral symmetry 5. Stable at pH 3–9 and at 60°C for 30 minutes 6. Causes infections in chickens, pigs, and plants

Question 55

Question: Enumerate the two groups of circoviruses and the diseases they cause.

Answer 55

a. Chicken anaemia virus (CAV) b. Porcine circovirus types 1 and 2 (PCV-1, PCV-2): Cause Post-weaning multisystemic wasting syndrome (PMWS)

Question 56

Enumerate the general characteristics of Asfarviridae.

Answer 56

Answer: 1. Enveloped DNA viruses 2. Size: 175–215 nm in diameter 3. Icosahedral symmetry 4. Replicate in cytoplasm of host cells and in soft ticks (Ornithodorus species) 5. Stable at 4–20°C and persists for months in meat

Question 57

What is the only genus in the family Asfarviridae, and what disease does it cause?

Answer 57

Answer: Genus: Asfivirus (Asfavirus) Disease: African Swine Fever (ASF)