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Questions and Answers
Which virus is associated with both shingles and chickenpox?
Which virus is associated with both shingles and chickenpox?
What is a common symptom of HSV eye infection?
What is a common symptom of HSV eye infection?
What is the main characteristic of HSV encephalitis?
What is the main characteristic of HSV encephalitis?
Which statement about herpes viruses is false?
Which statement about herpes viruses is false?
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Which method is typically used to detect herpes viruses in tissue studies?
Which method is typically used to detect herpes viruses in tissue studies?
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Which of the following viruses is specifically linked to encephalitis?
Which of the following viruses is specifically linked to encephalitis?
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What is a common aspect of the latency characteristic of herpes viruses?
What is a common aspect of the latency characteristic of herpes viruses?
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In the context of tissue studies, which method is integral to the detection of herpes viruses?
In the context of tissue studies, which method is integral to the detection of herpes viruses?
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Which symptom is commonly associated with herpetic infection around the eyes?
Which symptom is commonly associated with herpetic infection around the eyes?
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Which statement is true regarding shingles and chickenpox viruses?
Which statement is true regarding shingles and chickenpox viruses?
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What is the main clinical manifestation of HSV encephalitis?
What is the main clinical manifestation of HSV encephalitis?
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Which of the following herpes viruses is associated with Epstein-Barr virus?
Which of the following herpes viruses is associated with Epstein-Barr virus?
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What condition results from the activation of the varicella-zoster virus later in life?
What condition results from the activation of the varicella-zoster virus later in life?
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Which method is primarily used for diagnosing herpes virus infections in patients?
Which method is primarily used for diagnosing herpes virus infections in patients?
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What is a common factor shared by all herpes viruses regarding their lifecycle?
What is a common factor shared by all herpes viruses regarding their lifecycle?
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What crucial role does latency play in the lifecycle of herpes viruses?
What crucial role does latency play in the lifecycle of herpes viruses?
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Which herpes virus is primarily associated with the development of encephalitis?
Which herpes virus is primarily associated with the development of encephalitis?
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What technique is most effective for identifying antibodies specific to herpes viruses?
What technique is most effective for identifying antibodies specific to herpes viruses?
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Which condition is a result of the reactivation of the varicella-zoster virus later in life?
Which condition is a result of the reactivation of the varicella-zoster virus later in life?
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Which statement accurately describes the impact of herpes viruses on the brain?
Which statement accurately describes the impact of herpes viruses on the brain?
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Study Notes
Infection and Immunity Module
- This module covers infections and immunity
- Dr. Ibrahim Naqid is the lecturer
- The module is offered at Zakho Medical College, University of Zakho
Herpesviruses
- Herpesviruses are widely distributed
- Eight human herpesviruses have been identified
- Herpes simplex virus 1 & 2
- Varicella-zoster virus
- Epstein-Barr virus
- Human cytomegalovirus
- Human herpesviruses 6 to 8
Biological properties
- Herpesviruses are DNA viruses
- All herpesviruses encode enzymes needed for viral replication
- Viral replication destruction of host cells
- All establish latent infections that last the host's lifetime
Structure
- Nucleocapsid surrounded by a lipid envelope
- Prefer mucosal surfaces
Transmission
- Those transmitted by oral secretions are common in children, with high seroprevalence
- Those transmitted by genital secretions are common in adolescence, with lower seroprevalence
What is latency?
- Virus remains dormant within host cells
- The virus is not actively replicating or causing symptoms but persists.
Terms
- Primary infection: First infection with a virus
- Latency: Virus remains dormant within cells
- Recurrent infection: Recurrence of symptoms -HSV 1 & 2 - neurons -VZV (HHV-3) – dorsal root ganglia -EBV (HHV-4) - B cells -CMV – bone marrow
Clinical Presentation
- Herpes viruses can integrate their genetic material onto host cells.
- Some herpesviruses have oncogenic potential in both animals and humans, including lymphoproliferative disorders
- Primary infection with human herpesviruses is generally mild or subclinical, especially in immunocompetent hosts, sometimes presenting with a rash or skin eruption.
- In immunocompromised hosts, primary herpesvirus infection can present with severe, life-threatening illness.
- Factors influencing clinical presentation: -Host-pathogen interactions -Immune status of the host -Affected organ
- Different tissue tropisms: •CMV-retina and GIT •VZV-lung tissue •HSV-encephalitis
International Names of Herpes Viruses
- HHV-1: Herpes simplex 1 – Alphaherpesvirinae – Short replication cycle – Cytolytic
- HHV-2: Herpes simplex 2 – Alphaherpesvirinae – Short replication cycle – Cytolytic
- HHV-3: Varicella-Zoster – Alphaherpesvirinae – Latent Sensory ganglia
- HHV-4: Epstein-Barr virus – Gammaherpesvirinae – Latency in T or B cells
- HHV-5: Cytomegalovirus – Betaherpesvirinae – Restricted Host range – Long replication cycle
- HHV-6: HHV-6 – Betaherpesvirinae – Cytomegalic
- HHV-7: HHV-7 – Betaherpesvirinae – Long replication cycle – Cytomegalic
- HHV-8: Kaposi's Sarcoma Virus – Gammaherpesvirinae– Latency in T or B cells
Alphaherpesviruses
- HSV-1
- HSV-2
- HSV-3
HSV-1 and HSV-2
- Worldwide distribution and endemic in humans
- HSV-1: Primary infection through oropharyngeal secretions (95% seropositive by age 5)
- HSV-2: Transmitted through sexual contact (10-30% seropositive in adults)
- Causes various diseases:
- Herpes skin rashes
- Herpes simplex stomatitis
- Herpes simplex eye infection (red, swollen eye)
- Encephalitis (brain inflammation)
Varicella-Zoster Virus (VZV)
- Endemic in most populations
- Primarily transmitted via respiratory route
- 10% of the population remains uninfected
Chickenpox (Varicella)
- Vesicular skin rash starting on body and head, becoming itchy, often healing without scarring.
Shingles (Herpes Zoster)
- Painful skin rash, with vesicles limited to a dermatome (area of skin supplied by a single spinal nerve).
Betaherpesviruses
- Human CMV (Cytomegalovirus)
- Human Herpesvirus 6 & 7
Cytomegalovirus (CMV)
- Transmitted via person-to-person contact
- Close contact
- Saliva
- Sexual contact
- Perinatally
- Organ transplant
- Blood transfusion
- Clinical course:
- Self-limiting disease usually doesn't need treatment
- Can cause serious problems in people with deficient immune systems
- AIDS patients
- Transplant patients
- Pregnancy
- Can cause colitis, retinitis, pneumonitis, etc
Gammaherpesviruses
- Epstein-Barr Virus (EBV)
- Kaposi's Sarcoma-Associated Herpesvirus (KSHV or HHV-8)
Epstein-Barr Virus (EBV)
- Spread through droplets
- Causes infectious mononucleosis (glandular fever)
- Other diseases:
- African lymphoma
- Nasopharyngeal carcinoma
- B-cell lymphoma
Infectious Mononucleosis
- Symptoms: Extreme fatigue, fever, sore throat, swollen lymph nodes, and sometimes swollen liver or spleen and rash.
- Diagnostics: Monospot test, helpful but not definitive; further testing is sometimes necessary to confirm the presence of EBV
- Distinguished from other mononucleosis cases- EBV mononucleosis is caused by EBV
- Non-EBV mononucleosis is milder version caused by CMV
Diagnosis
- Clinical presentation
- Serology by ELISA (detects antibodies)
- Molecular by PCR (detects viral DNA)
- Histopathology (tissue studies)
- For CMV: blood sample, urine, saliva, or other body tissues to detect the virus or antibodies
Treatment
- Specific antiviral therapy
- Acyclovir – HSV and VZV
- Cidofovir – CMV and resistant HSV
- Ganciclovir – CMV and EBV
Hepatitis Viruses
- Five hepatitis viruses are identified:
-Hepatitis A
- Hepatitis B
- Hepatitis C
- Hepatitis D
- Hepatitis E
- Transmission and types:
- A & E are transmitted orally;
- B, C, D are transmitted vertically (sex and blood including contaminated needles)
HAV (Hepatitis A Virus)
- RNA virus
- Oral transmission
- Acute infection only.
- Vaccine available
- Endemic in most countries.
- Diagnosed through ELISA IgM test.
- Pathogenesis: Enters via gut, replicates in digestive tract and spreads to liver, multiplies in hepatocytes. Transient viremia (virus in blood), excretion in stool two weeks before onset of symptoms
HBV (Hepatitis B Virus)
- DNA virus
- Transmission: Mother-to-baby, sex, blood, blood products (contaminated needle, etc)
- Acute and chronic disease
- Vaccine available
- Diagnosed by ELISA, IgM and IgG.
- Pathogenesis: Parenterally transmitted, replicates in the liver, shed into the bloodstream, highly infectious.
HCV (Hepatitis C Virus)
- RNA virus
- Transmission: Mother-to-baby, sex, blood, blood products (contaminated needle, etc). Also from organ donation.
- Acute and chronic.
- Vaccine unavailable.
- Diagnosed through PCR test.
HDV (Hepatitis D Virus)
- RNA virus
- Defective virus needing HBV for replication.
- Transmission: Mother-to-baby, sex, blood, blood products (contaminated needle, etc).
- Acute and chronic
HEV (Hepatitis E Virus)
- RNA virus
- Oral transmission
- Acute infection only.
- Vaccine unavailable. Diagnosed by ELISA IgM and PCR for specific sequences in stool
- Pathogenesis similar to HAV
Clinical Features of Hepatitis
- Patients experience similar symptoms, especially in the acute stage
- Specific diagnosis is made through laboratory tests.
- Common symptoms include: anorexia, nausea, vomiting, right upper quadrant pain, raised liver enzymes (AST and ALT), jaundice. Anicteric cases are also very common.
Vaccine Availability
- Vaccines are available for Hepatitis A and B.
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Description
This quiz covers the key concepts of herpesviruses within the Infection and Immunity module at Zakho Medical College. Learn about the biological properties, transmission methods, and latency of herpesviruses, including the eight human herpesviruses identified. Test your knowledge on their structure and implications in medical science.
