HSV Latent Infections and Reactivation

Latent Infections (HSV)

• Occur in neuronal cells, where infectious virus is not detected
• Can be reactivated in neurons, leading to productive infection recurrence
• No cure, but medications like acyclovir may prevent or shorten outbreaks

Mechanism of Latency and Reactivation

• A. Penetration into skin, local replication, and entry of virus into cutaneous neurons
• B. Centripetal migration in the axon of uncoated nucleocapsids
• C. Synthesis of infectious virions
• D. Centrifugal migration of infectious virions to epidermis

Viral STI: Genital Herpes

• Pathogenesis: Herpesvirus kills epithelial cells at infection site
• Blisters may form at sites far from initial infection
• Babies can become infected during birth, causing congenital (neonatal) herpes
• Congenital herpes is usually caused by HSV-2, transmitted from mother to infant during vaginal delivery

Epidemiology of Genital Herpes

• Quadruples the risk of HIV infection
• Diagnosis is based on characteristic lesions
• Acyclovir or other antiviral agents can lessen symptoms
• Circumcised males are at lower risk of infection
• Condoms often provide little protection

Diagnosis of Herpes Simplex Virus Infections

• Clinical syndrome recognition
• Electron microscopy
• Virus isolation
• PCR (nucleic acid amplification)
• Viral serology is generally not useful for acute diagnosis

Viral Cardiovascular and Systemic Diseases: Infectious Mononucleosis

• Signs and symptoms: severe sore throat, fever, swollen lymph nodes, fatigue, appetite loss, and skin rash
• Pathogen: Epstein-Barr virus (EBV or HHV-4)
• Virulence factors: establishes latent infection in host, suppresses apoptosis of infected B cells

Pathogenesis and Epidemiology of Infectious Mononucleosis

• Transmission occurs via saliva
• EBV infects B lymphocytes (receptors)
• Majority of adults have antibodies against EBV
• 50% of 5-year-olds are infected, usually asymptomatic
• Teens are usually symptomatic

Diagnosis, Treatment, and Prevention of Infectious Mononucleosis

• Diagnosed by presence of large, lobed B lymphocytes and neutropenia
• Treatment focuses on relieving symptoms
• Prevention is difficult due to widespread EBV occurrence

Herpesviridae Affecting Humans

• Human viruses include:
  • Herpes simplex 1
  • Herpes simplex 2
  • Epstein-Barr virus
  • Varicella zoster
  • Cytomegalovirus
  • Human herpes virus 6, 7, and 8

Herpesvirus Virons

• Icosahedral, 120-200 nm, pleomorphic, enveloped, surface glycoprotein spikes
• Linear dsDNA genomes, 50-100 genes
• Replicate in the nucleus of cells
• Tends to develop latent infections
• Many primary infections are asymptomatic (except Varicella zoster)

Genital Herpes

• Caused by herpes simplex viruses type 1 (HSV-1) or type 2 (HSV-2)
• Targets epithelial or nerve cells
• Signs and symptoms: small blisters on or around genitals, rectum, or mouth, fever, malaise, myalgia, and decreased appetite

This quiz covers the mechanisms of latent infections and reactivation of Herpes Simplex Virus (HSV), including how it occurs in neuronal cells, prevention, and treatment options.