Herpesviruses (ch 43) PDF

Read Quiz Understanding Human Herpesviruses: A Comprehensive Overview Human herpesviruses (HHVs) are a diverse group of viruses that cause a range of diseases, from mild to life-threatening. This overview aims to guid...

Read Quiz Understanding Human Herpesviruses: A Comprehensive Overview Human herpesviruses (HHVs) are a diverse group of viruses that cause a range of diseases, from mild to life-threatening. This overview aims to guide readers through the main features, pathogenesis, epidemiology, clinical syndromes, and treatments associated with the most prevalent human herpesviruses. Structure and General Characteristics of Herpesviruses Key Structural Features Large, enveloped virions: The viruses possess an icosahedral protein capsid and a lipid envelope with glycoprotein spikes. Double-stranded DNA genomes: The genetic material of these viruses is double-stranded DNA. Intracellular Replication: Virus replication and capsid assembly occur in the nucleus, with release mechanisms including exocytosis, cell lysis, and cell-to-cell spread. Various Infections: Capable of causing lytic, persistent, latent, and immortalizing infections (e.g., Epstein-Barr virus). Host Interactions and Immune Response Manipulation of Host Immune Response: Herpesviruses synthesize https://www.studocu.com/en-us/notes 12/5/24, 1 23 AM Page 1 of 4 :  proteins that interfere with the host immune system. Latency: Establishment of latency in neurons and immune cells, such as B cells. Reactivation: Trigger factors for reactivation include stress, ultraviolet B exposure, and immunosuppression. Specific Herpesviruses and Associated Diseases Herpes Simplex Virus (HSV) HSV-1 and HSV-2 Epidemiology and Transmission Lifelong Infection: Both types of HSV can establish lifelong infections with recurrent outbreaks. Transmission: Transmission primarily occurs through oral and genital secretions and through direct contact with lesion fluids. At-Risk Populations: Children (HSV-1), sexually active adults (HSV-2), healthcare workers, immunocompromised individuals, and neonates. Clinical Syndromes HSV-1: Commonly associated with oral herpes (cold sores). HSV-2: Commonly associated with genital herpes. Diagnostic Methods: Typically diagnosed through PCR and culture methods. Treatment and Prevention Antiviral Drugs: Includes nucleoside analogs like acyclovir, valacyclovir, and famciclovir which inhibit viral DNA polymerase. None of these treatments can eliminate latent infection. Preventive Measures: Use of antiviral prophylaxis, wearing gloves for healthcare workers, and avoiding contact during active lesions. Varicella-Zoster Virus (VZV) https://www.studocu.com/en-us/notes 12/5/24, 1 23 AM Page 2 of 4 :  Clinical Manifestations Chickenpox (Varicella): Typically affects children, causing widespread vesicular rash. Shingles (Herpes Zoster): A recurrence of VZV later in life, characterized by painful dermatomal rashes. Pathogenesis and Immunity Initial Infection: Begins in the respiratory tract, spreading via viremia to the skin. Latency and Reactivation: VZV establishes latency in dorsal root and cranial nerve ganglia. Reactivation (shingles) is often seen in the elderly and immunocompromised individuals. Epidemiology and Control Transmission: Through respiratory droplets and direct contact. Vaccinations: Live attenuated vaccines (Oka strain) and adjuvanted subunit vaccines for zoster prevention are available. At-Risk Populations: Young children, adults, immunocompromised individuals, and the elderly. Cytomegalovirus (CMV) Clinical Implications Congenital CMV: Most common cause of viral birth defects in the US. Symptoms in neonates include hearing loss, microcephaly, and retinitis. Adult Infections: Symptoms can range from asymptomatic to mononucleosis-like illness in healthy individuals and severe disease in immunocompromised patients. Transmission and Prevention Transmission: Via direct contact with body fluids such as saliva, urine, breast milk, and sexual contact. Prevention: Emphasis on avoiding exposure, particularly for pregnant https://www.studocu.com/en-us/notes 12/5/24, 1 23 AM Page 3 of 4 :  women and immunocompromised individuals. Epstein-Barr Virus (EBV) Pathogenesis Infectious Mononucleosis (Glandular Fever): Characterized by lymphocytosis and symptoms resulting from the robust T-cell response against infected B cells. Latency and Associated Cancers: Establishes latency in memory B cells, with associations to Burkitt's lymphoma, nasopharyngeal carcinoma, and other lymphomas in immunocompromised individuals. Epidemiology and Transmission Transmission: Primarily through saliva ("kissing disease") and close contact. Geographic and Seasonal Trends: Worldwide distribution with no seasonal pattern. Risk Groups: Adolescents, young adults, and immunocompromised individuals. Conclusion Human herpesviruses are a pervasive and complex group of pathogens, with the ability to cause various acute and chronic diseases. Control and prevention rely heavily on understanding their transmission, epidemiology, and the development of effective antiviral therapies and vaccines. While significant strides have been made in managing these infections, ongoing research is crucial to addressing the challenges posed by these enduring viruses. https://www.studocu.com/en-us/notes 12/5/24, 1 23 AM Page 4 of 4 :