DNA Viruses

What is abortive infection

No progeny virus particles are produced

What is lytic infection

Virus production is followed by cell death

What are the outcomes of infection by DNA virus

Lytic, intracellular transformation, latent infection

What are poxviruses

Large brick shape/oval; dsDNA; core in double membrane and lipoprotein envelope w virions; the ONLY virus that replicate in cytoplasm

What is the only DNA virus that replicates in the cytoplasm

Poxvirus

What are the major poxviruses

Variola, Orf, Monkeypox, Molluscum contagiosum

What is the pathogenesis of smallpox

Inhalation of virus → Replicate in upper respiratory tract epithelium → Spread to lymph node and infect phagocytic cells → Viremia → Disseminate to liver, spleen and skin

Smallpox clinical presentation

High fever, fatigue, severe headache, backache, malaise → Vesicular rash in mouth then body → Vomiting, diarrhea, bleeding

What is Mpox (MPX)

Zoonotic virus endemic to Africa

MPox transmission

Infected primate/rabbit/mice/guinea pig contact; human to human (respiratory, skin lesion, contaminated object); mother to fetus

What is the clinical manifestation of MPox

Fever and chill, malaise, headache, myalgia, back pain; rash on face/trunk and genital/perianal region

Cutaneous findings of MPox

Diffuse rash → Pustules → Rash umbilicates → Crust and desquamates

Lab diag for Mpox

Specimen from skin, lesions or crust; PCR swab from rash; eosinophilic inclusion bodies

What is Molluscum contagiosum

Benign; infect human ONLY; 2wk-6mo incubation; LOCAL; contact spread

What are the signs of Molluscum contagiosum

Infect epidermal cells to form fleshy lesion with umbilicated center and painless; itchy, red, sore and swollen with cheesy material

What is ORF

Epidermis infection (uncommon), contract from infected sheep/goats through skin cuts; papulovesicular region on hand

What is JC and BK virus

Polyomavirus BKV and JCV; in urine and feces and aerosol; primary infection is almost asymptomatic; latent infection caused by immunosuppressed people

What is progressive multifocal leukoencephalopathy (PML)

Subacute demyelinating disease in immunocompromised patient; neurological symptoms followed by arm/leg paralysis and death

What is the early symptoms of PML

Lack of coordination, difficulty speaking, weakness

What is the progressive symptoms of PML

Dementia, speech loss, vision loss

What is the prognosis for people that are diagnosed with PML

Live 1-4 months and most die within 2 years

Lab diag for BKV and JCV

PML diag: PCR viral DNA in CSF; MRI sign of lesion; Histology shows demyelination; Urine cytology show dense basophilic intranuclear inclusion

What is HPV

Small naked capsid, icosahedral, circular dsDNA; infect squamous stratified epithelia; cause tumors that can be benign or malignant

Pathogenesis of HPV

Cutaneous (hand, foot, flat) warts; lesion on mucosal/genital areas

Lab diag for HPV

Does NOT grow in cell culture; HPV Ab test only used in research

What are herpesviruses

Mainly establish LIFELONG persistent infection

Human herpes simplex virus type 1 and 2 infection

Mostly asymptomatic; skin and mucoid lesion (mouth/tongue, genital); involve mucocutaneous surface and CNS; maintained by latency neural cells

What is the pathogenesis of HSV (cutaneous)

Entry by skin/mucous membrane → Viral multiplication → Cell lysis → Vesicles → Ulcers

What is the pathogenesis of HSV (CNS)

Viral multiplication → Sensory nerve → Root ganglia → Latency → Reactivation

What is oral herpes

Primary infection is asymptomatic; lesion with fever and enlarge lymph node; palate/gums/tongue/lip and face

Genital herpes

Cause ulcer and pustule; women: labia, cervix, vaginal mucosa, mons pubis; men: shaft

HSV in finger

Finger (herpetic whitlow); virus spread when finger touches other things

HSV in Trunk, extremities and head

Wrestlers (herpes gladiatorum), Rugby (scrum pox)

HSV in eye

Keratoconjunctivitis; branching dendritic lesion in cornea

HSV with burn/dermatitis

Eczema herpeticum

HSV in CNS

Cause meningitis/encephalitis; during reinactivation

Neonatal HSV

Skin, eyes, mucous membrane; CNS infection; disseminated infection

HSV lab diag

Look at skin and mucous membrane; confirm with Tzanck smear for multinucleated giant cell

What is HHV-3 Varicella zoster virus

Primary = Chicken pox, recurrent = Zoster; has exanthem

What is exanthem

Pink macules and papules surrounded by white halo. start at trunk and spread to neck and proximal area

HHV-3 clinical presentation

Varicella or Shingles

HHV-3 diag

Look at skin lesion; Tzanck test for multinucleated giant cells in vesicle fluid; Ab blood test; PCR skin blister

What is Epstein Barr virus (HHV4)

90% ppl have been infected and have Ab; >90% Mononucleosis caused by HHV4

What is infectious mononucleosis

Kissing disease; common in childhood; 2-4 week symptoms; morbilliform/pappular rash on arm/trunk (5%);

Mononucleosis clinical presentation

Fatigue, malaise, fever; sore throat; cervical lymphodenopathy; splenomegaly (rare), atypical lymphocytosis

EBV lab diag

Lymphocytosis and thrombocytopenia; monospot test positive; EBV Ab

What is cytomegalovirus (HHV5)

90% seropositive in elderly; perinatal and childhood infection; produce large intranuclear inclusion and smaller cytoplasmic inclusion

CMV infection outcomes

Asymptomatic; CMV mononucleosis; congenital CMV → Severe birth defect; disseminated disease in immunocompromised

Clinical manifestation of CMV

CMV mono: prolonged high fever, rubelliform rash; leukocytosis

CMV diag

DNA and Ag in body fuild; isolation of virus; cytopathology

What is HHV8

Transmit in saliva for high prevalence area; sexual transmission in low prevalence area; possible by drug infection/organ transplant/blood transfusion

What is Kaposi’s sarcoma associated herpesvirus (KSHV)

Vascular tumor = Kaposi’s sarcoma

HHV8 pathogenesis

Target B cells in mouth

Clinical manifestation of HHV8

Primary is asymptomatic; chronic asymptomatic infection; children may have fever and maculopapular rash

HHV8 manifestation in immunocompromised people

Fever, splenomegaly, lymphoid hyperplasia, pancytopenia, rapid onset kaposi sarcoma

What is the histopathology of KS lesion

Early macules to plagues that may become large nodules (tumor)

Lab diag of HHV8

Biopsy to find spindle tumor cell

What is adenovirus

Naked capsid virus; cause respiratory disease and sometimes in other organs

Adenovirus pathogenesis

Oral fecal and respiratory droplet transmission; replicate in intestinal epithelium (not serotype 40 and 41); Group C = latent infection in adenoid/tonsil

Respiratory presentation of adenovirus

Cough, nasal congestion, fever, sore throat; acute respiratory disease syndrome in military that can cause pneumonia

Adenovirus eye infection

Follicular conjunctivitis (pinkeye), pharyngoconjunctival fever; more serious = epidemic keratoconjunctivitis in adults

GI disease of adenovirus

Serotype 40 and 41 associated with infantile gastroenteritis

Other disease from adenovirus

Respiratory disease progress to severe pneumonia/disseminated infection; adenovirus hepatitis for liver transplant recipient; graft loss in heart recipient; HSC recipient get infection

Lab diag for adenovirus

Swab pharynx and nasopharynx; eye/cervix/urethra swab; urine; feces; CSF; Ag detection, isolation, serology

Adenovirus transmission

Aerosol, fecal matter, fomites; dirty pools, ophthalmologic instrument

What are the viruses that cause mucus membrane infection/infect skin or mucus membrane

HHV3 (VZV), HPV, HSV1 and 2

What viruses infect many systems

HHV4 (EBV), HHV5 (CMV), HHV8

Exanthematous viruses

HSV 6 and 7; parvovirus B19; rubella; rubeola

Respiratory virus

Adenovirus

CNS virus

JCV

Hepatitis causing virus

HBV