Virology Flashcards
DNA viruses
- Enveloped capsule viruses:
- Poxvirus
- Herpesvirus
- Hepadna
- Naked DNA
- Adenovirus
- Papilloma
- Parvovirus
They are double strand DNA (dsDNA) , in exception of parvovirus wich is ssDNA.
RNA viruses
- Encapsulated
- Paramyxovirus
- Rhabdovirus
- Orthmyxovirus
- Coronavirus
- Togavirus
- Flavivirus
- Naked RNA viruses
- Reovirus
- Calicivirus
- Picornavirus
They are ssRNA, except Reoviridae
Viral replication
- DNA viruses : replicate in the nucleus (except Poxvirus)
- RNA viruses: replicate in the cytoplasm (except influenza virus and retroviruses)
Process of the viral replication:
1) Attachment: viruses bind through specific interaction with the host cell surface components.
2) Penetration
3) Uncoating: release of nucleic acid
4) Macromolecular synthesis
5) Post-translational modification of proteins
6) Assembly
7) Release
Viral vaccines
- Live attenuated vaccines : induce humoral and cell-meadiated immunity. Smallpox, yellow fever, rotavirus, chickenpox, Sabin polio virus, MMR, influenza (intranasal)
- Killed: Induce only humoral immunity. Rabies, influenza (injected), Salk Polio, HAV vac.
- Subunit: HPV (types 6, 11, 16, 18)
Herpesviruses
- DNA virus, enveloped, double strand, linear genoma
- Herpes simplex virus-1
- Herpes simplex virus -2
- Varicella- Zoster virus
- Epstein Barr
- Cytomegalovirus
- Human herpes viruses 6 and 7
- Human herpes virus 8
Most common cause of encephalitis
Herpes virus simplex-1
Herpes simplex virus 1
Transmission: Respiratory secretions, saliva
Latent: trigeminal ganglia
Clinical significance: Gingivostomatitis, keratoconjunctivitis, herpes labialis, encephalitis.
Encephalitis : altered mental status, seizures, blindness, and/or aphasia.
Herpes simplex 2
Transmission : sexual contact, perianal
Latent: sacral ganglia
Clinical significance: Herpes genitalis, neonatal herpes. Painful genital vesicles. Viral meningitis.
Treatment: acyclovir
Varicella-Zoster virus
Transmission: respiratory droplets
Latent in dorsal root or trigeminal ganglia.
Clinical: chickenpox, shingles, encephalitis. Asynchronous rash
Most complication of shingles is post herpetic neuralgia
Epstein Barr virus
Human herpesvirus 4
Transmission: respiratory secretions, saliva. Kissing disease.
Infects B cells through CD21
Clinical significance:
- Mononucleosis: fever, hepatoesplenomegaly, pharyngitis, lymphadenopathy (posterior cervical nodes) . Abdominal pain, fatigue, malaise. Headaches, usually retro orbitral
Symptoms can persist within 2-3 weeks.
Avoid contact sports until resolution due to risk of splenic rupture.
-Associated with lymphomas and nasopharyngeal carcinoma.
Dx: monopost test positive
Cytomegalovirus
Human herpesvirus 5
Transmission: congenital, transfusion, sexual contact, saliva, urine, transplant
Infected cells have characteristic owl eye inclusions. Latent in mononuclear cells.
Clinical significance: Mononucleosis with monospot test negative . Congenital CMV
AIDS infection retinitis, hemorrhage, vision loss
Pneumonia in inmunocompromised patients.
Roseola infantum
Exanthem subitum
Human herpes virus 6 and 7
High fever for several days that can cause seizures, followed by diffuse macular rash.
Transmission: 6: respiratory droplets and saliva
7: saliva
HHV-7 less common cause of roseola
Roseola infantum
Exanthem subitum
Human herpes virus 6 and 7
High fever for several days that can cause seizures, followed by diffuse macular rash.
The rash is composed of either discrete, small, pale pink papules or a blanchable, maculopapular exanthem that is 1-5 mm in diameter. This rash may last 2 days.
The characteristic enanthem (Nagayama spots) consists of erythematous papules on the mucosa of the soft palate and the base of the uvula. The enanthem may be present on the fourth day in two thirds of patients with roseola.
Transmission: 6: respiratory droplets and saliva
7: saliva
HHV-7 less common cause of roseola
Kaposi sarcoma
Human herpes virus 8
Transmission: sexual contact
Disease: Kaposi sarcoma (neoplasm of endothelial cells)
Dark/violaceous plaques or nodules representing vascular proliferation.
Seen in HIV/AIDS and transplant patients
Herpes simplex virus identification method
Tzanck test: a smear of an opened skin vesicle to detect multinucleated giant cells.
Poxvirus
Enveloped virus with double strand and linear genoma
Smallpox : eradicated worldwide
Molluscum contagiosum: flesh-colored Papule with central umbilication.
Transmission: direct skin contact
Lesions may be located anywhere; however, a predilection for the face, trunk, and extremities is observed in children and a predilection for the groin and genitalia is observed in adults.
Adenovirus
No envelope, DS and linear DNA
Febrile pharyngitis : sore throat
Acute hemorrhagic cistitis
Pneumonia
Conjunctivitis “pink eye”
Gastroenteritis
It is transmitted via direct inoculation to the conjunctiva, a fecal-oral route, aerosolized droplets, or exposure to infected tissue or blood.
Papillomavirus
No envelope, DS and Circular DNA
HPV- warts (1,2,6,11)
HPV- cervical cancer (16,18)
Polyomavirus
No envelope, DS and circular
Parvovirus
No envelope, SS and linear
B19 virus- fifth disease- Erythema infectiosum: slapped cheeks rash in children
*aplastic crises in sickle cell disease,
Sings and symptoms: they appears after 1 week of exposure to the virus
Headache Sore throat Pruritus Fever Coriza Abdominal pain
Top five of virus diseases
Firth: measles Second: varicella Third: rubella Fourth: roseola Fifth: b19- erythema infectiosum
Hepadnavirus
Hepatitis A
Hepatitis B
Hepatitis C
Hepatitis D
