5_PICO_Flashcards
What is the genome structure of Picornavirus?
Picornavirus has a small linear +ssRNA genome, which is equivalent to mRNA. It is icosahedral and non-enveloped.
What are examples of Picornavirus?
Examples include Coxsackie, Echo, Polio, Rhinovirus, Entero71, and Entero72.
How is Picornavirus transmitted?
Transmitted via the fecal-oral route; however, the main infection site is not the GI tract, except Rhinovirus.
What is the receptor used by Picornavirus for attachment?
The receptor is ICAM (Intercellular Adhesion Molecule), which helps with virus attachment.
Where does Picornavirus replicate?
Replication occurs in the cytoplasm and is usually cytolytic. It initially replicates in the oropharynx, tonsils, and Peyer’s patches.
Define primary and secondary viremia in Picornavirus.
Primary viremia refers to the initial spread of the virus in the bloodstream. Secondary viremia occurs when the virus targets specific tissues and spreads further.
What tissues are targeted by Poliovirus?
Poliovirus targets motor neurons in the CNS, causing motor dysfunction or paralysis.
How many serotypes are there in Coxsackie virus?
Coxsackie virus has 30 serotypes.
What is the incubation period of Coxsackie virus?
The incubation period is 1-7 days.
What organs are targeted by Coxsackie B virus?
Coxsackie B virus targets the heart (myocarditis, pericarditis), lungs, and CNS (aseptic meningitis).
List clinical features of Coxsackie A virus.
Coxsackie A causes vesicular lesions (herpangina, hand-foot-mouth disease by A5, A16), rhino-like symptoms (A21, A24), and acute hemorrhagic conjunctivitis (A24).
What are the clinical manifestations of Coxsackie B virus?
Coxsackie B causes myocarditis and pericarditis (leading to heart failure, especially in older children), pleurodynia (Bornholm disease, or ‘devil’s grip’), and aseptic meningitis.
What does ‘Echoviruses’ stand for?
‘Enteric cytopathic human orphan’ (Echoviruses).
What clinical manifestation is associated with Echoviruses?
Echoviruses can cause aseptic meningitis with or without a rash.
How many serotypes does Poliovirus have?
Poliovirus has 3 serotypes.
Describe the transmission and target tissue of Poliovirus.
Poliovirus is transmitted via the fecal-oral route, usually in summer and autumn. It targets the skeletal muscle and motor system, including the anterior horn cells (AHC) and brainstem.
What is the incubation period of Poliovirus?
The incubation period is 5-20 days.
List the clinical presentations of Poliovirus.
- Asymptomatic (90%): Limited to the oropharynx and GIT.
- Abortive (5%): Features fever, headache, malaise, sore throat, and vomiting (‘minor illness’).
- Aseptic meningitis (2%): Presents with viral meningitis symptoms and minor illness.
- Paralytic polio (2%): Symptoms include minor illness followed by paralysis due to AHC and motor cortex involvement.
Describe the changes in CSF during Poliovirus infection.
Increased lymphocytes, increased protein, and normal glucose levels in the CSF.
What vaccines are available for Poliovirus?
- Salk ‘IPV’: Inactivated polio vaccine.
- Sabin ‘OPV’: Live attenuated polio vaccine.
Both provide lifelong immunity covering all 3 serotypes.
How many serotypes does Rhinovirus have?
Rhinovirus has 100 serotypes.
How is Rhinovirus transmitted, and what are its growth conditions?
Transmitted by direct contact with respiratory secretions. It shows optimal growth at 33°C.
What evolutionary mechanism contributes to Rhinovirus’s antigenic variation?
Rhinovirus exhibits antigenic drift, leading to frequent variations.
What receptor does Rhinovirus enhance to facilitate viral entry?
Rhinovirus enhances the ICAM receptor, facilitating more viral entry.
What are the common clinical symptoms of Rhinovirus infection?
Low-grade fever and runny nose are common symptoms.
What is more important in Rhinovirus immunity: antibodies or cell-mediated immunity?
Antibodies (Ab) are more important than cell-mediated immunity (CMI) in Rhinovirus infection.
What are the treatment and prevention strategies for Rhinovirus?
Treatment involves symptom relief (e.g., nasal vasoconstrictors). Pleconaril is not commonly used because the infection is self-limiting. Prevention includes hand washing and disinfectants.
