Virus and oral cavity

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Questions and Answers

What area of the body does Herpes Simplex Virus type 1 (HSV 1) predominantly affect?

Lower extremities

Hands and feet

Genital region

Oropharyngeal region (correct)

Which of the following is NOT commonly caused by Coxsackie Viruses?

Hand, Foot and Mouth Disease

Myocarditis

Meningitis

Genital herpes (correct)

What is a hallmark characteristic of Herpes Simplex Virus type 2 (HSV 2)?

Causes genital lesions (correct)

Causes lesions above the waist

Associated with orofacial sores

Linked to chickenpox

Which virus is primarily responsible for causing chickenpox?

Varicella-Zoster Virus Signup and view all the answers

Which symptom is typical for Hand, Foot and Mouth Disease?

Fluid-filled blisters on hands and feet Signup and view all the answers

What disease is primarily caused by the Epstein-Barr Virus (EBV)?

Glandular fever Signup and view all the answers

Which of the following complications is NOT associated with measles?

Swelling of testicles Signup and view all the answers

Which age group is most commonly affected by mumps?

Children Signup and view all the answers

How does Epstein-Barr Virus (EBV) persist in the human body after infection?

It becomes dormant in B-lymphocytes. Signup and view all the answers

What symptom is most characteristic of measles?

Exanthematous rash Signup and view all the answers

What is the chance of a male experiencing testicular pain if infected with mumps after puberty?

1 in 4 Signup and view all the answers

Which type of virus does not include Epstein-Barr Virus (EBV)?

Coxsackie Virus Signup and view all the answers

What is a significant complication associated with measles infection?

Fits and seizures Signup and view all the answers

What is the primary causative agent of chickenpox?

Varicella-Zoster virus Signup and view all the answers

Which symptom is characteristic of chickenpox?

Painless vesicular rash Signup and view all the answers

How is hand, foot, and mouth disease primarily transmitted?

By air and direct contact Signup and view all the answers

What is the seasonal occurrence pattern of herpangina?

Summer Signup and view all the answers

Which virus is known to infect most individuals during early childhood?

Epstein-Barr virus Signup and view all the answers

What is a common symptom of shingles?

Unilateral facial palsy Signup and view all the answers

Varicella infection is generally considered ____ in children.

Mild and self-managed Signup and view all the answers

Which of the following is NOT a common feature of hand, foot, and mouth disease?

High blood pressure Signup and view all the answers

Which condition is characterized by vesicles in the mouth and affects the faecal/oral route?

Herpangina Signup and view all the answers

What is the incubation period for Varicella?

2 weeks Signup and view all the answers

What characterizes the viral genome of vinis?

Contains either DNA or RNA, never both Signup and view all the answers

Which component of a virus gives it symmetry and protects the nucleic acid core?

Capsid Signup and view all the answers

What defines viruses as obligate intracellular parasites?

They require a living host cell to multiply. Signup and view all the answers

What is a common characteristic of the icosahedral type of viral capsid?

Contains 12 corners and 20 equilateral triangle facets. Signup and view all the answers

Which viral infection is known to potentially lead to Ramsay Hunt syndrome?

Varicella-Zoster Virus (Shingles) Signup and view all the answers

What is a complication associated with the Epstein-Barr Virus?

Burkitt's Lymphoma Signup and view all the answers

How is herpangina commonly presented in children?

It manifests on the soft palate. Signup and view all the answers

Which factor is NOT involved in tissue tropism for viral infections?

Type of viral nucleic acid Signup and view all the answers

What is the primary distinction between lytic and lysogenic replication of viruses?

Lytic replication requires host cells to be destroyed, whereas lysogenic replication does not. Signup and view all the answers

Which of the following viruses is associated with persistent infections?

HIV Signup and view all the answers

What role do capsomeres play in the viral assembly process?

They are responsible for incorporating viral nucleic acid. Signup and view all the answers

Which characteristic best defines viral latency?

The virus lies dormant within a host cell and does not produce symptoms. Signup and view all the answers

How does viral persistence differ from chronic viral infections?

Persistent infections involve stages of silent and productive infection. Signup and view all the answers

What is a critical step in viral replication once a virus has entered a host cell?

Host cell enzymes replicate the viral genome. Signup and view all the answers

Which virus is known for having significant dental implications due to its association with oral lesions?

Human Immunodeficiency Virus (HIV) Signup and view all the answers

How do viruses demonstrate tropism towards specific cell types?

By utilizing specific receptors on their capsid. Signup and view all the answers

Which classification of viruses is based on the arrangement of their structural proteins?

Symmetry Signup and view all the answers

What best defines persistent viral infections?

Infections where the virus remains dormant in host cells. Signup and view all the answers

Which type of nucleic acid can be found in viruses?

Double-stranded RNA or single-stranded DNA Signup and view all the answers

What distinguishes an icosahedral virus structure?

Its spherical symmetry with 20 triangular faces. Signup and view all the answers

Which of the following statements about viral entry into host cells is false?

All viruses require energy to enter host cells. Signup and view all the answers

What is the primary function of transcription in the viral replication process?

To produce mRNA necessary for enzyme synthesis Signup and view all the answers

Which of the following best describes how viruses achieve cellular tropism?

By binding to specific host receptors on cell membranes Signup and view all the answers

Which process describes how viruses penetrate host cells after attachment?

Direct fusion with the host membrane Signup and view all the answers

Which viral classification is characterized by high mutation rates compared to DNA viruses?

RNA viruses Signup and view all the answers

During which phase of viral replication can the virus not be detected in the host cell, indicating a 'pause' in infectivity?

Eclipse phase Signup and view all the answers

What is a key characteristic of persistent viral infections?

They integrate into the host's genome and can remain dormant Signup and view all the answers

Which of the following viruses is known for its significant implications in dental health?

Hepatitis B virus Signup and view all the answers

What is the key difference between endocytosis and fusion in the context of viral penetration?

Endocytosis allows viruses to enter by engulfing them, while fusion merges membranes of both virus and host. Signup and view all the answers

Study Notes

Varicella-Zoster

Caused by human herpes virus 3
Commonly known as chickenpox and shingles
Chickenpox usually mild and self-managed
Chickenpox can be more serious if contracted in adulthood
Chickenpox has a 2 week incubation period
Symptoms include fever, rash, papules becoming vesicular and itchy, but painless
Shingles are a reactivation of the varicella-zoster virus
Shingles manifest as painful vesicular rash
Shingles occur in dorsal root ganglia and trigeminal nerve

Ramsay Hunt Syndrome

A rare form of shingles
Affects the facial nerve
Symptoms include vesicular rash on the tympanic membrane and auditory canal
Causes unilateral facial palsy

Hand Foot & Mouth Disease

Primarily caused by group A coxsackie viruses
Symptoms include malaise and spots on buttocks, groin, hands and feet
Transmission through air, coughing, faecal contact and contaminated objects
Common outbreak in nurseries

Herpangina

Symptoms include vesicles in the mouth, malaise and sore throat
Caused by Coxsackie A virus
Primarily occurs in summer
Transmission through faecal-oral route or air droplets
Self-managed

Epstein-Barr Virus (EBV)

Also known as Human Herpesvirus 4
Most people are infected in early childhood
When contracted in teens or young adulthood can cause infectious mononucleosis aka glandular fever
EBV becomes dormant and people remain infected for life
EBV lives in latent form in B-lymphocytes
Human are the only known host
EBV can cause:
- Glandular fever
- Burkitt’s Lymphoma
- Nasopharyngeal carcinoma
- Oral Hairy Leukoplasia

Mumps

Usually a childhood illness
Causes parotitis (inflammation of the salivary glands)
Causes painful swelling
If contracted after puberty males can have pain and swelling of the testicle
One in 20 females can get swelling of the ovaries
One in 20 can have temporary hearing loss
One in 1000 can get viral meningitis
One in 20 can get acute pancreatitis

Measles

Also known as measles morbillivirus
Most highly infectious disease known
Transmitted by air droplets and surfaces
Causes a characteristic exanthematous rash
Enters the body through the respiratory tract
Associated symptoms include headache, fever, sore throat and Koplik’s spots
Complications include:
- Stillbirth and miscarriage in pregnancy
- Vision loss
- Subacute sclerosing panencephalitis (rare, fatal brain complication)
- Fits and seizures
- Encephalitis

Koplik’s Spots

White spots with a red halo on the inside of the cheek
Characteristic of measles

Herpes Simplex (HSV 1 & 2)

HSV 1 generally causes orofacial lesions (above the belt)
HSV 2 generally causes genital lesions (below the belt)

Viral Genome

Contains either DNA or RNA, never both.
Can be linear or circular, single stranded, or double stranded.

Capsid

Protective outer layer of the virus.
Surrounds the nucleic acid core.
Composed of numerous subunits called capsomers.
Provides symmetry and is made of proteins called protomers.

Envelope

Surrounds the nucleocapsid.
Bilayer of lipoprotein and glycoproteins.
Viruses without an envelope are called "naked viruses."

Enzymes

Play a crucial role in the infection process.
Some enzymes contain their own nucleic acid polymerases that transcribe the viral genome into mRNA during replication.

Obligate Intracellular Parasites

Viruses can only multiply within a living host cell.

Icosahedral Viruses

Polygonal shape.
Capsid has 12 corners, 20 facets (equilateral triangles), and 30 edges.
Most stable type of virus.
Found in human pathogenic viruses such as herpes.

Filamentous Viruses

Linear, thin, thread-like or rod-shaped.

Head-Tail Viruses

Icosahedral head.
Filamentous body.

Viral Tropism

Refers to the specific host cells, tissues, or organisms that a virus can infect.
Influenced by:
- Presence of cellular receptors for viral entry.
- Availability of transcription factors for viral replication.
- Cellular receptors of proteins on the cell or viral surface.

Varicella-Zoster Virus (Human Herpesvirus 3)

Causes chickenpox in children and shingles in adults.

Management of Varicella-Zoster Virus

Hydration.
Good diet.
Non-steroidal anti-inflammatory drugs (NSAIDS) for fever relief (e.g., paracetamol, ibuprofen).

Shingles

Reactivation of the varicella-zoster virus.
The virus resides in the dorsal root ganglia.
Reactivation triggered by trauma, immunosuppressant drugs, or other unknown factors.
Dormant virus travels through nerve fibers to the skin when reactivated causing unilateral rash.

Management of Shingles

Requires medical management.
Can lead to Ramsay Hunt syndrome (shingles of the facial nerve) which causes:
- Unilateral facial palsy.
- Tinnitus.
- Change or loss of taste.
- Dry mouth.
- Oral manifestations.
- Potential for toothache-like pain due to hyposensitivity.

Herpangina

Viral infection presenting on the soft palate.
Affects children aged 3-10 years old.
Symptoms last for up to 10 days.
Contagious for 3-8 weeks after infection.
Can cause difficulty swallowing.

Epstein-Barr Virus (Human Herpesvirus 4)

Can cause various conditions, including Burkitt's lymphoma.

Virus Replication

Viral replication begins with the attachment of the virus to the host cell.
Following attachment, penetration occurs, allowing the virus or its genome to enter the host cell.
Penetration can happen via endocytosis, fusion, or translocation.
After penetration, the virus undergoes uncoating, where the lipid membrane and protein capsid surrounding the nucleic core are removed.
The viral nucleic acid becomes free and acts as a template for mRNA synthesis.
Transcription occurs, producing mRNA that encodes enzymes necessary for viral replication.
Viruses take advantage of the existing cell structures to replicate themselves.

Viral Release

Lytic replication results in the death of the host cell.
Lysogenic replication allows the host cell to continue living and functioning normally.

Viral Persistence

Persistent infections are characterized by the continuous presence of the virus within the host, without necessarily causing immediate death or significant damage to the host cells.
Examples of persistent viral infections include HIV, Epstein-Barr, Human Cytomegalovirus.

Viral Latency

Virus latency is the ability of a virus to remain dormant within a cell, characterized as the lysogenic part of the viral life cycle.
Latent viral infections are a type of persistent infection, distinct from chronic viral infections.

Viral Tropism

Viral tropism describes the selective ability of a virus to infect specific cells, tissues, or host species.
Viral tropism is determined by the presence of specific receptors on the host cell that the virus can bind to.

Features of Viruses

Viruses are infectious particles that reproduce by hijacking the machinery of a host cell.
Viruses consist of a DNA or RNA genome enclosed within a protein shell called a capsid.
Some viruses possess an external membrane envelope.
Viruses exhibit diverse shapes, structures, genome types, and host preferences.
Viruses reproduce by infecting host cells and reprogramming them to produce more viruses.

Classification of Viruses

Viruses are classified based on their symmetry and nucleic acid type.
Symmetry can be icosahedral, filamentous, or head-tail.
Nucleic acid can be DNA or RNA, with variations in strandedness (single or double) and type (DNA or RNA).

Key Structures of Viruses

The capsid encloses the viral genome, providing structural integrity.
The nucleocapsid consists of the viral genome and associated proteins.
The envelope, if present, is a lipid bilayer surrounding the capsid.
Viral enzymes facilitate various steps in the replication process.

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Description

This quiz covers important infectious diseases such as varicella-zoster, Ramsay Hunt Syndrome, and Hand Foot & Mouth Disease. It includes information on causes, symptoms, transmission, and complications associated with these conditions. Test your knowledge on these diseases and their impact on health.