3 Herpes Viruses: Properties, Pathogenesis, Clinical Findings

Herpesviruses

Belong to the Herpesviridae family and include eight known human herpesviruses (HHVs)

Herpes Simplex Virus Type 1 (HSV-1)

Type of herpes simplex virus belonging to the Herpesviridae family

Herpes Simplex Virus Type 2 (HSV-2)

Type of herpes simplex virus belonging to the Herpesviridae family

Varicella-Zoster Virus (VZV or HHV-3)

Type of herpes virus belonging to the Herpesviridae family

Epstein-Barr Virus (EBV or HHV-4)

Type of herpes virus belonging to the Herpesviridae family

Cytomegalovirus (CMV or HHV-5)

Type of herpes virus belonging to the Herpesviridae family

Human Herpesvirus 6 (HHV-6)

Type of herpes virus belonging to the Herpesviridae family

Human Herpesvirus 7 (HHV-7)

Type of herpes virus belonging to the Herpesviridae family

Human Herpesvirus 8 (HHV-8)

Also known as Kaposi's sarcoma-associated herpesvirus, belonging to the Herpesviridae family

Herpesviruses Genome

Linear double-stranded DNA genome

Herpesviruses Capsid

Icosahedral capsid structure

Herpesviruses Envelope

Possess a lipid envelope derived from the host cell nuclear membrane, containing essential glycoproteins for host cell entry

Herpesviruses Replication Cycle

Includes attachment, latency, reactivation, replication, and entry processes

Herpes Simplex Virus Pathology

Causes cytolytic infections leading to cell necrosis and inflammation, with characteristic histopathologic changes

Herpes Simplex Virus Latency

Remains latent in ganglia and reactivates triggered by various factors, leading to recurrent infections

Oropharyngeal Disease in HSV Infections

Primary infection may be asymptomatic, while recurrent infections present with vesicles at the lip border

Keratoconjunctivitis in HSV Infections

Causes severe keratoconjunctivitis with potential for corneal opacification and blindness

Genital Herpes Clinical Findings

Primary infection characterized by severe symptoms, while recurrent infections are milder with possible asymptomatic shedding

Skin Infections in HSV

Includes traumatic herpes, herpetic whitlow, and herpes gladiatorum, with severe cases in individuals with skin disorders

VARICELLA-ZOSTER

Virus that causes chickenpox and shingles, likely reactivated by waning immunity.

HERPES ZOSTER

Also known as shingles, involves severe pain in sensory nerve distribution preceding rash.

EPSTEIN-BARR VIRUS

Virus transmitted through saliva, often asymptomatic in children but causes mononucleosis in adults.

CYTOMEGALOVIRUS

Virus spread through close contact with bodily fluids, causing systemic infections and establishing lifelong latent infections.

HUMAN HERPESVIRUS 6

Virus primarily transmitted through saliva, causing roseola infantum and reactivating in immunocompromised individuals.

Postherpetic Neuralgia

Prolonged pain following shingles, common in elderly individuals.

Mononucleosis

Symptoms include headache, fever, sore throat, and enlarged lymph nodes, lasting 2-4 weeks.

Burkitt Lymphoma

Cancer linked to Epstein-Barr virus, particularly in African children.

CMV Infection in Normal Hosts

Often asymptomatic in older children and adults, can cause mild infectious mononucleosis syndrome.

CMV Infection in Immunocompromised Hosts

Primary infections are severe, leading to pneumonia, colitis, and increased morbidity.

Congenital CMV Infections

Transmitted in utero, can cause severe congenital defects like hearing loss and mental retardation.

Roseola Infantum

Caused by Human Herpesvirus 6, characterized by high fever and rash in children.

Encephalitis

Condition resulting from Human Herpesvirus 6 reactivation, affecting the brain.

Reactivation

Occurs in transplant patients, leading to complications like delayed recovery and neurological issues.

Complications

Issues impacting overall health outcomes.

HHV-7

Human Herpes Virus 7 primarily targeting T lymphocytes and causing clinical conditions.

Latency

Established primarily in T cells, reactivates later in life.

Roseola

Symptoms similar to HHV-6 infection, causing high fever and rash.

Asymptomatic

Many HHV-7 infections show no symptoms but can still spread the virus.

HHV-B

Herpes B Virus causing roseola infantum, often asymptomatic in infants.

Neurological Complications

Severe complications like encephalitis and myelitis from HHV-B infections.

HHV-8

Human Herpes Virus 8 transmitted through saliva, sexual contact, and blood transfusions.

Immunity

Interferon and various immune responses against pathogens like viruses.

Seroconversion

Antibodies specific to herpesviruses detected in serology.

PCR

Used to detect viral DNA in clinical specimens.

Epidemiology

Transmission and prevalence details of infections.

Antiviral Therapy

Drugs like acyclovir used to manage active herpes virus infections.

Vaccination

Available for VZV (chickenpox and shingles vaccines).

Y-Globulin

High VZV antibody titer to prevent severe disease in varicella-exposed patients.

Preventive Measures

Avoiding direct contact, barrier protection, and antiviral prophylaxis to prevent HSV transmission.