Virology-RNA Viruses Flashcards
Flaviviruses
Envelope
SS
Capsid icosahedral
Diseases:
- Yellow fever
- Dengue
- west nilo virus
Yellow fever
Flavivirus transmitted by aedes mosquitoes.
Symptoms: fever, black vomitus and jaundice.
Councilman bodies on liver biopsy
Rotavirus
1 cause of fatal diarrhea in children (infantile gastroenteritis)
No envelope, DS linear, icosahedral capsid
Prevention: vaccine
Symptoms: anorexia, low grade fever, watery diarrhea , vomiting, abdominal cramps.
Complications: dehydration
Management: no antibiotics, only supportive
Rhinovirus
Picornavirus. Nonenvelope RNA virus
Incidence in fall and spring
Cause of common cold: low fever, sneezing, runny nose, nasal congestion, cough , headaches, sore throat.
Complications: sinusitis, otitis media, chronic bronchitis
Treatment: symptomatic management
Influenza virus
Orthomyxoviruses. Enveloped SSRNA
*Types : Influenza A or B
*Disease: influenza
-headache, malaise, fever, chills, myalgias, anorexia, bronchiolitis, croup (cough), vomiting.
*Complications: Can lead to Reye syndrome or Guillain-Barré syndrome
*Transmission: direct contact, respiratory.
*Dx: rapid test, culture and clinical symptoms
*Treatment: amantadine or zanamivir/oseltamivir
*Prevention: killed vaccine, injection.
*Pathogenesis:
Envelope contains two glycoproteins: H (hemagglutinin) and N (neuraminidase)
Two process:
- antigenic shift :
Sudden and major change in the surface of a virus due to a process call Genetic reassortment : two viruses which infect simultaneously the cell mix and match their genome.
Cause pandemics: Production of a new agent to which population has no immunity. - Antigenic drift:
Slight changes in antigenicity due to random mutations in H and/or N genes.
Cause epidemics
Sudden shift
Gradual drift
Rubella virus
Togavirus. German measles
Rubella symptoms: fever, postauricular and other lymphadenopathy , arthralgias, confluent Maculopapular rash that starts on face and spreads centrifugally to involve trunk and extremities.
CONGENITAL RUBELLA (TORCHES)
- Patent ductus arterioso, pulmonary stenosis, cataracts, microcephaly, deafness. Blueberry muffin appearance due to dermal extra medullary hematopoiesis.
- The effects are more serious if the maternal infection is acquired during the first 16 weeks.
PaRaMyxovirus
Envelope. SS negative linear
Parainfluenza: croup
Mumps
Measles
RSV
All contains surface F protein wich cause respiratory epithelial cells to fuse and form multinucleated cells
Croup
Acute laryngotracheobronchitis
Seal-like barking cough and inspiratory stridor
Narrowing of upper trachea and sub glottis leads to characteristic steeple sign on x Ray .
Measles (rubeola) virus
Prodromal fever with cough , coryza and conjunctivitis
Eventually, koplik spots (bright red spots with blue-white center on Buccal mucosa
Followed 1-2 days later by a Maculopapular rash that starts at the head /neck and spreads downward .
3 C of measles: Cough, Coryza, Conjunctivitis
Mumps virus
*Symptoms:
PAROTITIS
ORCHITIS: can cause sterility (specially after puberty)
ASEPTIC MENINGITIS
PANCREATITIS
- Management:supportive care
Ebola virus
Filovirus
Cell target: endothelial cells, phagocytes, hepatocytes
Incubation time : 21 days
Symptoms: abrupt onset of flu like symptoms, diarrhea, vomiting, high fever, myalgias,
Transmission: direct contact with body fluids, fomites .
Diagnose: PCR within 48 hrs of symptom onset.
High mortality rate
Treatment: supportive care , strict isolation of infected individuals.
Hepatitis A virus
Family: Picornavirus
Features: iscosahedral, Nonenvelope virus
Transmission: fecal-oral
Incubation: weeks (short)
Clinical course : *Asymptomatic
*Acute : fever, jaundice, ALT AST high, hepatomegaly
Prognosis: good
Liver biopsy: hepatocytes swelling, monocytes infiltration, councilman bodies.
No carrier state
Dx: serologic markers: IgM and IgG
Prevention: vaccine
Hepatitis B virus
Family: DNA hepadnavirus
Transmission: parenteral, sexual, perinatal
Incubation: long (months)
Clinical course: initially like a serum sickness: fever, arthralgias, rash
Prognosis 50% good resolution, 50% chronic infection
Carrier state common.
Liver biopsy: granular eosinophilic ground class appearance .
Dx: serologic markers: HBsAg, Anti-HBs, HBcAg, Anti-HBc, HBeAg, Anti-HBe
Tx:
The primary treatment goals for patients with hepatitis B infection are to prevent progression of the disease, particularly to cirrhosis, liver failure, or hepatocellular carcinoma (HCC).[2] Pegylated interferon alfa (PEG-IFN-a), entecavir, and tenofovir disoproxil fumarate are the first-line agents in the treatment of hepatitis B disease.
Complication: chronic infection: carcinoma hepatocellular and /or cirrhosis
Hepatitis B serologic markers
Hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) (marker of infectivity) are the first markers that can be identified in the serum in acute disease. Hepatitis B core antibody (anti-HBc) immunoglobulin M (IgM) follows.
For patients who recover, seroconversion to hepatitis B surface antibody (anti-HBs) and hepatitis B e antibody (anti-HBe) is observed. The anti-HBc is of the IgG class. Patients with persistent HBsAg lasting more than 6 months are considered to have chronic hepatitis.
Acute hepatitis B
Serology markers positive:
- HBsAg : antigen found on surface of HBV.
- HBeAg: indicates active viral replication and therefore high transmissibility
- Anti-HBc: IgM (anticuerpo al antigeno Del core)
