Picornaviridae Flashcards
Picornaviridae are primarily where?
Respiratary and gastrointestinal (enteroviruses) viruses
What are the characteristics of the Picornaviridae virus?
Small(pico=small), sperical, naked, +RNA virus
What are the 2 classes of Piconaviridae virus?
Enterovirus and respiratory virus
What are the 3 types of enteroviruses?
1-Poliomyelitis
2-Coxsackie virus
3-Echovirus
What are the 2 types of respiratory viruses?
1-Rhinovirus
2-Coronavirus
How are enteroviruses transmitted?
via the fecal-oral route
When the enteroviruses are ingested what do they infect?
the oro-pharyngeal mucosa and lymphoid tissue
How do most patients react once infected with the enterovirus?
they remain asymptomatic
What is the asymptomatic pattern of Poliomyelitis?
Most common, up to 90% of infections. Occurs when the replication of the virus is restricted to the GI tract
What is there to know about Abortive poliomyelitis?
Occurs in about 5% of infected individuals
First symptomatic result or polio infection is fever and occurs in the first weeks of infection
Patient may exhibit a general malaise which may be accompanied by vomiting, a headache and a sore through
What is there to know about Non-paralytic poliomyelitis?(aseptic meninges)
Patient experiences stiff neck and vomiting, virus has now progressed to the brain and infected the meninges. Spontaneous recovery
What is there to know about Paralytic poliomyelitis?
About 4 days after the end of the first minor symptoms, the virus spreads from the blood to the anterior horn cells of the spinal cord and the the motor cortex of the brain. The degree of paralysis depends on which neurons are affected and the amount of damage
What is there to know about postpolio syndrome?
This afflicts victims of an earlier poliovirus infection but the virus is no longer present, involves firther loss of function in affected muscle
What is the name of the vaccine for polio?
Salk Vaccine
What is the Salk vaccine?
Formalin-killed preparation of normal wild type polio virus
How does the Salk vaccine work?
Elicits good humoral (IgG) immunity and prevents transport of the virus to the neurons where it would otherwise cause paralytic polio
What is the name of the other vaccine for Polio?
Sabin Vaccine
What type of vaccine is the Sabin vaccine?
Live viral vaccine
How is the Sabin vaccine given and how does it work?
It is given orally. Grows in the human gut where the wild type virus grows. It can’t migrate to the neurons through. Replicates a normal infection since the virus actually grows in the vaccinee and it elicits both a humoral and cell-mediated immunity
Picornavirus, enterovirus, what is the second type after Poliomyelitis?
Coxsackie virus
What is caused by the Coxsackie virus and what are the types?
There are many infections caused y Coxsackie viruses, most of which are never diagnosed precisely. 2 types are Type A and Type B
What is Coxsackie virus type A usually associated with?
rashes
What can coxsackie virus type A cause?
Herpangina
Hand, foot, and mouth disease
Hemorrhagic conjunctivitis
Aseptic meningitis-enteroviruses are the major cause of viral meningitis
What can Coxsackie virus type B cause?
Localized internal lesions
also can cause meningitis, rashes and fever like type A
Pluerodynia-the devils grip
Myocarditis and pericarditis
How is coxsackie virus transmitted?
Fecal oral route similar to polio virus transmission
Picornavirus, enterovirus type 3 is?
Echovirus
What is echovirus?
enteric cytopathic human orphan virus
What diseases does echovirus cause?
Asceptic meningitis, respiratory infection, gastroenteritis, skin rashes, and fever
The second type of picornavirus is? After enterovirus…
Respiratory viruses
What are the 2 types of respiratory viruses?
1) Rhinovirus
2) Coronavirus
1/3 of household colds are caused by this virus?
Rhinovirus
How many derotypes of rhinovirus are therre and why does this pose a problem?
There are 100 serotypes explaining why vaccines against rhinoviruses have proved difficult to develop
How are rhinoviruses spread?
Spread by aerolsols and infect the upper respiratory tract. Also spread by fomites and other forms of direct contact
What are the symptoms of rhinovirus infection?
Discharge or blocked nasal passages often accompanied by sneezes, and perhaps a sore throat
What antibodies are developed in response to a rhinovirus infection?
IgA in nasal secretions and IgG in the bloodstream
Do rhinoviruses enter the blood stream?
No so the mucosal IgA response is the most important
How long does one have immunity to a particular serotype of rhinovirus?
1 to 2 years but there are many serotypes against which protection is not gained
Describe the structure of a coronavirus
Enveloped viruses with a +ss RNA genome similar to rhinovirus
What do coronaviruses cause?
a significant percentage of all common colds in humans
What is SARS?
atypical pneumonia caused by a coronavirus
How is SARS transmitted?
Close person to person contact. Transmitted most readily by respiratory droplets produced when an infected person coughs or sneezes
What is the best way to prevent the spreading of SARS?
Interrupt the infection chain by washing hands
How does SARS start and how does it develop?
Most people have mild respiratory symptoms at the outset. After 2-7 days, SARS patients may develop a dry cough. Most patients develop pneumonia
