Virus Flashcards
Virus
Partículas infecciosas de menor tamaño (>600 nm.), de ARN o
ADN recubierto de una cápsula de proteínas con o sin membrana lipídica. Son
parásitos obligados, incapaces de replicarse sin la ayuda de un huésped. Se
considera que NO están vivos.
Virulencia
Capacidad de los microorganismos patógenos para infectar y producir casos graves o fatales (ej: la variante
omicron es más virulenta porque infectó a más personas) → Grado de daño que produce un agente a su huésped.
Factores de virulencia → promueven la eficiencia de:
- Replicación viral
- Transmisión viral
- Acceso y unión del virus al tejido diana
- Escape del virus de las defensas del huésped
Progresión de la enfermedad viral
El periodo de incubación. puede proceder sin síntomas (asintomático) o puede producir síntomas tempranos inespecíficos inducidos por citocinas
Prodromo → Fiebre, dolor corporal, cefalea o escalofríos
Normalmente las infecciones virales se resuelven por el sistema inmunitario innato del hospedador sin síntomas
Virus:
A virus is an obligate intracellular parasite. Accordingly, it can only survive within a host cell and depends on it for replication and metabolic processes.
Virion:
The infective form of a virus when present outside of cells, which consists of DNA or RNA, a protein capsid, and sometimes an envelope.
Receptores HIV
CD4, CXCR4, CCR5
Receptor Rhinovirus
ICAM-1
Receptor SARS-CoV-2
ACE2
Receptor Epstein-Barr virus/ Human herpes virus 4
CD21
An 82-year-old woman is brought to the physician by her daughter because of a 3-day history of a runny nose, headache, and cough. The patient’s grandson recently had similar symptoms. Her vital signs are within normal limits. Pulse oximetry on room air shows an oxygen saturation of 99%. Lungs are clear to auscultation. Testing of nasal secretions is performed to identify the viral strain. Electron microscopy shows a non-enveloped RNA virus with an icosahedral capsid. Binding to which of the following is responsible for the virulence of this virus?
ICAM-1/ CD54 - Rhinovirus
Expresión de ICAM-1 inducida por la inflamación a la propagación del Rhinovirus
Rhinovirus binds to ICAM-1 (CD54) expressed on respiratory epithelial cells. Infected epithelial cells release inflammatory cytokines such as interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-α), which lead to clinical symptoms and induce further expression of ICAM-1 molecules, helping viral progeny to infect neighboring cells.
A 13-year-old boy is brought to the physician by his parents because of several bumps on his fingers. He has no history of serious illness and is up-to-date on all immunizations. Physical examination shows several superficial, flesh-colored, hyperkeratotic papules along the dorsal aspect of the fingers with minimal surrounding hyperpigmentation. The remainder of the physical examination is normal. What virus is most likely responsible for this patient’s findings?
HPV is a nonenveloped DNA virus with a circular, double-stranded genome and icosahedral capsid shape. Certain serotypes of HPV (particularly 1, 2, and 4) are the cause of common warts, which appear as skin-colored, scaly papules (sometimes with a cauliflower-like appearance) on the elbows, knees, fingers, and/or palms. This type of wart is most common in childhood and adolescence.
RNA viruses that are transmitted via the fecal-oral route
Rotavirus, norovirus, poliovirus, coxsackievirus, echovirus, hepatitis A virus, and hepatitis E virus, which are all nonenveloped viruses with icosahedral capsids.
Phenotypic mixing
Phenotypic mixing is the process by which a virus retains its own genetic material but becomes coated with surface proteins of a different coinfecting virus.
