MICI: Overview of Herpesviruses

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What are some serious complications associated with CMV in newborns?

Severe sore throat

Fatigue

Rash after antibiotics

Hearing loss (correct)

Which diagnostic method is primarily used to identify CMV?

Heterophile antibody testing

Polymerase Chain Reaction (PCR) (correct)

Enzyme-linked Immunosorbent Assay (ELISA)

Complete Blood Count (CBC)

What is the incubation period for symptoms of infectious mononucleosis caused by EBV?

4-6 weeks (correct)

1-2 weeks

6-8 weeks

2-4 weeks

What treatment is commonly used for serious CMV infections in immunocompromised patients?

Ganciclovir Signup and view all the answers

Which of the following clinical manifestations is NOT associated with EBV infectious mononucleosis?

Hearing loss Signup and view all the answers

What is a characteristic feature of the cells used in diagnosing CMV?

Large, owl-eye cells Signup and view all the answers

Asymptomatic shedding refers to which scenario in viral transmission?

Spread of the virus with no visible symptoms Signup and view all the answers

What is the primary reason for supportive care in EBV treatment?

There is no specific antiviral treatment Signup and view all the answers

Which of these is incorrectly matched with its associated virus?

CMV - 'kissing disease' Signup and view all the answers

What is the main characteristic of latency in viruses like EBV?

Virus remains dormant within host cells Signup and view all the answers

Which of the following features is NOT characteristic of the Herpesviridae family?

Non-enveloped virions Signup and view all the answers

What is a significant characteristic of asymptomatic shedding in herpes infections?

It can account for up to 70% of transmissions Signup and view all the answers

What is the primary mode of transmission for Cytomegalovirus (CMV)?

Bodily fluids like saliva and breast milk Signup and view all the answers

In which condition is Neonatal herpes most likely to occur?

During vaginal delivery from an infected mother Signup and view all the answers

Which of the following accurately describes the treatment for Herpes Simplex Virus (HSV)?

Antivirals reduce outbreak severity but do not cure HSV Signup and view all the answers

What factor significantly influences the recurrence of HSV-2 infections?

Stress or immune compromise Signup and view all the answers

What laboratory technique is most effective for detecting HSV DNA?

Polymerase chain reaction (PCR) Signup and view all the answers

Which statement about Epstein-Barr Virus (EBV) is true based on the overview of Herpesviruses?

EBV is commonly associated with infectious mononucleosis. Signup and view all the answers

What is true regarding the virion structure of herpesviruses?

They possess an icosahedral capsid and an enveloped structure. Signup and view all the answers

Which aspect of herpesviruses contributes to their latency?

Replication in the nucleus, particularly in nerve cells Signup and view all the answers

Study Notes

Overview of Herpesviruses

The Herpesviridae family includes numerous viruses, such as HSV-1, HSV-2, EBV, and CMV.
Herpesviruses have a distinctive structure: an icosahedral capsid, 120-200 nm in size, often with pleomorphic shapes.
They are enveloped, contain double-stranded DNA (dsDNA), and have a linear genome with 50-100 genes.
Replication occurs inside the nucleus, leading to latency, particularly in nerve cells.

Herpes Simplex Virus (HSV-1 & HSV-2)

HSV-1 predominantly causes oral infections, while HSV-2 typically causes genital infections.
Both viruses can cause infections in areas outside their typical locations (crossover).
They are prevalent worldwide, and many infections are asymptomatic.
Transmission occurs through direct contact with blisters or secretions from infected areas, including the genitals and mouth.
A significant portion of HSV transmission (up to 70%) occurs without visible symptoms (asymptomatic shedding).

Clinical Manifestations of HSV

Symptoms include blisters appearing on or around the affected areas.
Systemic symptoms can include fever, malaise, muscle pain, and loss of appetite.
Neonatal herpes (caused by HSV-2) is often severe and potentially life-threatening, primarily occurring during vaginal delivery.

HSV Recurrence and Key Facts

HSV can become latent in nerve cells and reactivate under conditions such as stress or immune compromise.
High recurrence rates are common, particularly for HSV-2 (90% have at least one recurrence, 38% have six or more, and 20% have 20 or more recurrences).

Diagnosis and Treatment of HSV

Polymerase chain reaction (PCR) is frequently used to detect HSV DNA.
Serology, which detects antibodies, is less useful for diagnosing acute infections due to latency and recurrence.
Acyclovir and similar antiviral medications can reduce outbreak severity but cannot cure HSV.
Prophylactic antiviral medications may be used to reduce the frequency of recurrences.

Cytomegalovirus (CMV)

CMV is common and often asymptomatic in healthy individuals.
It can cause complications in individuals with compromised immune systems and during pregnancy, posing risks to the developing fetus.
Transmission occurs through bodily fluids, including saliva, blood, urine, breast milk, and sexual contact.
CMV can cross the placenta, affecting the fetus.

Clinical Manifestations of CMV

In immunocompromised individuals, CMV can lead to symptoms similar to mononucleosis or severe complications, especially in newborns (e.g., birth defects, hearing loss).

Diagnosis of CMV

CMV can be identified by large "owl-eye" cells containing inclusions.
Diagnostic methods include PCR, electron microscopy, and immunofluorescence.

Treatment of CMV

Ganciclovir and Fomivirsen (for eye infections) are used to treat serious CMV infections in immunocompromised patients.
Supportive care is often the primary treatment for healthy individuals with CMV.

Epstein-Barr Virus (EBV)

Also known as Human Herpesvirus 4 (HHV-4), EBV causes infectious mononucleosis ("mono").
It becomes dormant in B cells and is associated with some cancers, particularly in immunocompromised individuals.

Transmission of EBV

EBV is commonly transmitted through saliva, earning it the nickname "kissing disease."
Many infected individuals are asymptomatic carriers, especially children.

Clinical Manifestations of Infectious Mononucleosis

Symptoms include a severe sore throat, fever, swollen lymph nodes, fatigue, an enlarged spleen, and a rash (especially after antibiotics).
The incubation period is 4-6 weeks, and symptoms can last 2-8 weeks, with fatigue often persisting.

Diagnosis and Treatment of EBV

Diagnosis involves observing atypical large B cells, neutropenia (low neutrophil count), and performing heterophile antibody testing (e.g., Monospot).
Treatment typically focuses on supportive care, as specific antiviral therapy is generally ineffective.
Avoiding contact sports is recommended for those with symptomatic mono to prevent spleen injury.

Key Terms and Concepts for Review

Latency: the virus remains dormant within host cells, often becoming active later.
PCR: a common diagnostic tool for herpesviruses, used to amplify viral DNA.
Heterophile Antibodies: used in EBV diagnosis; they cross-react with animal blood cells.
Asymptomatic Shedding: the virus can spread without noticeable symptoms, particularly in HSV and CMV.
Antiviral Medications: Acyclovir for HSV; Ganciclovir for CMV; supportive care for EBV.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz explores the Herpesviridae family, focusing on key members such as HSV-1 and HSV-2. It discusses their structures, modes of transmission, and clinical manifestations. Additionally, the quiz highlights the prevalence and asymptomatic nature of herpes infections.