Viruses List

Question 1

Herpes simplex (1 and 2)

Family and subfamily

Structure and type

Spread

Causes

Treatment

Answer 1

Herpesviruses, alphaherpesviruses

Icosahedral, enveloped, linear dsDNA

Spread via direct lesion contact. HSV1 by non-sexual means, HSV2 by sexual means. Possible spread to neonate during delivery and maybe encephalitis

1⁰ and 2⁰ lesions, latent infection remains in ganglia of sensory neurons supplying area. Affects oral mucosa (gingivo-stomatitis), skin (lesions), genital tract, eye (conjunctivitis), brain (encephalitis). Fever, lymphangitis, lymphadenopathy, viraemia.

Acyclovir, valaciclovir (encode own thymidine kinase so susceptible to these antivirals)

Question 2

Human herpes virus 6 and 7

Family and subfamily

Type

Infect

Cause

Answer 2

Herpesviruses, betaherpesviruses

dsDNA

B and T cells. Viruses shed in body fluids

Roseola, usually in childhood: 1⁰ illness = fever, then macular rash. Adults: infective mononucleosis syndrome

Question 3

Human herpes virus 8

Family and subfamily

Type

Causes

Answer 3

Herpesviruses, gammaherpesviruses

dsDNA, envelope

Kaposi’s sarcoma. Malignant cells = endothelial. Sites: skin, lymphnodes, GI tract.

Question 4

Hepatitis B

Family

Type and structure

Transmission

Host cells

Causes

Treatment

Answer 4

Hepadnavirus

Circular dsDNA but some ssDNA parts, icosahedral capsid, envelope. Replication via virus-encoded RT

Transplacentally, perinatally, postnatally (sex, transfusion, needles, injury contamination). Outcome depends on age/sex/immune status of pt and virion dose

Hepatocytes

Postnatal: acute hepatitis. Some clear, some die (fulminant hep), some chronic carriers (usually transplancental or perinatal). May proceed to cirrhosis -> 1⁰ hepatocellular carcinoma

Reverse transcriptase inhibitors, pegylated interferon

Question 5

Varicella zoster virus

Family and subfamily

Type

Varicalla causes and complications

Varicella transmission

Zoster causes and complications.

Answer 5

Herpesviruses, alphaherpesviruses

dsDNA

Chickenpox. Complications: pneumonitis, cerebellar ataxia syndroma, encephalitis, secondary bacterial infection of vesicles, thrombocytopenia, arthritis, myocarditis, appendicitis, glomerulonephritis. Can cross placenta -> scarring, limb hypoplasia

Respiratory tract/conjunctivae, multiplication in local epithelial cells and lymphoid tissue -> 1⁰ viraemia. Spread to lymphoid tissue all over body -> 2⁰ viraemia -> infect skin and mucous membranes -> rash.

Shingles. Latent infection in dorsal root ganglia and if reactivated -> skin lesions. Complications: conjunctivitis, dissemination.

Question 6

Cytomegalovirus

Family and subfamily

Type

Transmission

Causes

Treatement

Answer 6

Herpesviruses, betaherpesviruses

dsDNA

Transplacental, direct contact, inhalation of respiratory droplets, kissing, sex, transplants. Virus shed in bodily fluids.

SCENARIOS:

1) Intraauterine damage: transmitted to foetus, some will become deaf/intellectually impaired/growth retardatation/jaundice/thrombocytopenia.

2) Asymptomatic infection: breast milk, direct contact etc. most asymptomatic but will establish chronic latent infection which can be reactivated

3) Pts 1⁰ infected with CMV/undergoing reactivation may have glandular fever symptoms (fever, malaise, sore throat, hepatitis)

4) In immunocompromised worse complications: pneumonitis, oesophagitis, colitis, hepatitis, pancreatitis etc. Life threatening.

Ganciclovir or valganciclovir (not susceptible to acyclovir)

Question 7

Epstein-Barr virus

Family and subfamily

Type

Infects

Transmission

Causes

Answer 7

Herpesviruses, gammaherpesviruses

dsDNA

Epithelial cells (lysis) and B cells (latent infection and continous division)

Respiratory droplets, direct contact

SCENARIOS: 1) Asymptomatic infection: latent, possible reactivation

2) Infectious mononucleosis (glandular fever): sore throat, fever, malaise, lymphadenopathy, +/- hepatitis and splenomegaly.

3) Malignant neoplasms: Burkitt’s lymphoma, B cell lymphomas, nasopharyngeal carcinoma, oral hairy leukoplakia

Question 8

Human immunodeficiency virus 1 (HIV1)

Family and subgroup

Type and shape

Transmitted

Infects

Causes

Answer 8

Retrovirus (reverse transcribe RNA -> DNA), lentivirus

Linear ssRNA +ve polarity, icosahedral (vase shaped) capsid, spiked envelope. Gp120 spike docks CD4

Vertically (sex, needles, blood transfusion)

CD4 T cells, macrophages, dendritic cells.

Virus replicates when host cell activated. Invitro causes T cell death via direct cytopathic effect and giant cell formation. In vivo cells CD8 may also kill infected CD4. CD4 count falls -> immunodeficiency. Fever, sweats, weight loss, infections (viruses, mycobacteria, protozoa, fungi), malignancies (Kaposi’s sarcoma, lymphomas, squamous cell carcinoma). If CD4 count below 200/cumm = AIDS.

Question 9

Human immunodeficiency virus 2 (HIV2)

Family and subfamily

Type

Compared to HIV1?

Answer 9

Retrovirus, lentivirus

Linear ssRNA + polarity

Confined to W Africa, transmitted like HIV1 but immunosuppresion less severe

Question 10

Human T-lymphotrophic virus 1 and 2 (HTLV-1/2)

Family

Type

Transmitted

Causes

Answer 10

Retrovirus

ssRNA + polarity

Vertically and by sex, transfusion and needles

HTLV1: Tropical spastic paraparesis, uveitis, lymphoma/leukaemia of T-cells

HTLV2: Not linked to any particular disease