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97 Cards in this Set
- Front
- Back
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Paramyxoviruses are:
a) ssRNA b) dsRNA c) ssDNA d) dsDNA |
a) ssRNA
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what is the genome of paramyxoxiruses?
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Single-stranded RNA, linear, nonsegmented, negative-sense
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parmamyxoviruses resembles w/c 2 virus families?
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rhabdovirus & filovirus
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T/F: paramyxovirus is enclosed by an envelope?
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True
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replication of paramyxovirus occurs where in the host cell?
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cytoplasm
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what are the 2 membrane glycoproteins that are key to the pathogenicity of all paramyxoviruses?
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H/HN or G & F protein
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what are the 3 functions of the F protein found on paramyxoviruses?
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1) enables virus to fuse cells & form syncytia. 2) enables viral penetration by fusion of viral envelope w/ plasma membrane. 3) allow direct intercellular spread by cell to cell fusion
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what is the function of intercellular spread by cell to cell fusion seen in paramyxoviruses?
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it functions to allow transfer of infectious nucleocapsids to adjacent cells while evading the body's circulating Abs
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w/ paramyxoviruses, how does the cell respond to infection?
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T/F: when talking about F proteins in paramyxoviruses, they must be cleaved first in order to be biologically active?
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true
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what is one way some nonpermissive cells work in making paramyxoviruses noninfectious?
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prevent cleavage of F proteins that must be cleaved to become biologically active
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w/ paramyxoviruses, how does the cell respond to infection?
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Cells respond to H, HN or G by eliciting a neutralizing antibody that inhibits adsorption of virus to cell receptors, thus inhibiting paramyxovirus infection
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what is the replication process of measles?
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The virus gains access to the human body via the respiratory tract, where it multiplies locally; the infection then spreads to the regional lymphoid tissue, where further multiplication occurs. Primary viremia disseminates the virus, which then replicates in the reticuloendothelial system. Finally, a secondary viremia seeds the epithelial surfaces of the body, including the skin, respiratory tract, and conjunctiva, where focal replication occurs
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in measles, on w/c day does viremia occur?
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after 6 days
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what are the s/sx of measles?
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cough, runny nose, inflamed conjunctiva & Koplik's spots
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w/ measles infection, is the body susceptible to other infections? if so what are they?
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Infection decreases the resistance of respiratory epithelium to secondary bacterial infections such as pneumonia and otitis media
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what are the different immunity & vaccination methods seen w/ measles?
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natural immunity against reinfection is very effective. passive immunization to protect immunocompromised pts who are unimmunized. there is also a live vaccine that is given to children
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w/ the available vaccine for measles, is this dz under control? if not where & what is the problem seen?
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no it's not. in developing countries, it's seen in malnourished infants & is one of the leading causes of death.
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severity of measles is affected by what 3 things?
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young age, low SES, & malnutrition
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passive immunization entails giving what to the pt?
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administration of Abs
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what are the complications seen w/ measles?(3)
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subacute sclerosing panencephalitis, subacute measles encephalitis, & acute postinfectious measles encephalitis
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w/c of the measles complications can manifest itself years after acute dz?what is its Px?
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subacute sclerosing panencephalitis. fatal as a result of the slow spread of virus in the brain
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w/c of the measles complications is the most dangerous complication & what the case fatality?
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acute postinfectious measles encephalitis w/ 15% fatality
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w/c measles complication occurs only in immunocompromised children?why does this dz occur?
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subacute measles encephalitis. it results b/c the body fails to eliminate virus infected cells as the body lacks cytotoxic T cells
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How is mumps transmitted?
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transmitted by saliva or other respiratory fluids
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what are the clinical features of mumps?
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distorted face & edematous enlargement of the salivary glands
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How does mumps present in infants?
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it's often asymptomatic or presents as a respiratory infection
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what are the infections caused by paramyxoviruses?
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measles, mumps, RSV, & parainfluenza
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what are the complications resulting from mumps? results in what?
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encephalitis w/c may progress in unilateral nn deafness
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what does - stranded RNA mean?
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when these viruses enter the cell, they are not able to begin translation immediately but they must first be transcribed into + RNA so they use RNA dep RNA polymerase w/c is found in the capsid of all -RNA viruses
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w/c virus is the only virus w/ dsRNA?
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reovirus w/c includes the rotavirus
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describe the genome of most DNA viruses? what is the exception?
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they have - strand & + strand but only the + strand is read & therefore replicated while the - strand is ignored. Parvoviruses are unique in that they have ssDNA
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what are the 2 types of capsids?
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icosahedral & helical
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w/c type of viruses are helical capsids?
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only RNA viruses have helical capsids
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w/c viruses are DNA?
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herpes, hepadna, adeno, papova, parvo, & pox (HHAPPPy)
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of the DNA viruses, w/c is the most complex?
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Pox & their structure is very complex & looks like a box (POX in a box)
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of the DNA viruses, w/c 3 are naked?
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"a woman must be naked for the PAP smear exam" PApova, Adeno, PArvo
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w/c virus is bullet shaped? what is its genome?
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rhabdo w/c is -ssRNA & is enveloped
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on w/c viruses do we find HA?
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on orthomyxoviruses & paramyxoviruses
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what is the function of Hemagglutinin (HA) proteins?
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attach to host sialic acid receptors w/c are found on the surfaces of RBCs. Sialic acid Rs are also found on RT cell membranes & HA bind to these & causes fusion of the host cell w/ the virion membrane
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in w/c viruses do we find NA?
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orthomyxovirus & parmyxoviruses.
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what is the function of neraminidase NA?
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it cleaves neraminic acid w/c is an important component of mucin
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How do viral NA & HA work together against the host cell? how can PTX overcome this?
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they act as tag team to overcome the host's defenses. NA cleaves the cell mucin barrier, while HA fuses to the cell's sialic acid residues enabling viral adsorption & penetration. Drugs called neraminidase inhibitors can work against NA & Abs against HA prevent binding & infection
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what is the genome of rhabdovirus?
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ssRNA virus
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w/c viruses are classified in the order mononegavirales?
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rhabdo, filo, & paramyxo
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what is the genus of rhabdovirus?
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lyssavirus
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w/c RNA viruses are the only dsRNA?
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Reovirus
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w/c RNA viruses are icosohedral?
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picorna, calici, toga, flavi
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what is the genome of mononegavirales?
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non-segmented, -ssRNA & non-infectious
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from the reading, are there any viruses that are -ssRNA & naked?
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no, the -ssRNA are all enveloped.
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what are the vectors of transmission of a rabies virus?
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bite or scratch, aerosol transmission from an infected animal, tissue transplants from infected humans
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the IP of rabies?
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14-90 days
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what are the early symptoms of rabies?
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fever, headache, & general malaise
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Dx of rabies in animals?
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direct fluorescent Ab test using brain tissue of animals suspected to be rabid
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Dx of rabies in humans?
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RT-PCR or IF assays on serum, skin biopsy, spinal fluid, or saliva specimens to detect rabies Ag or Ab to the virus
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what is the most definitive means of rabies Dx?
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virus cultivation
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How does virus cultivation of rabies work?
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inoculation of saliva, salivary gland & brain tissue intracerebrally into mice. Death w/n 28 days.
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what is the pre-exposure prophylaxis of rabies?
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active immunization w/c is human diploid cell vaccine (HDCV). It's given in 3 doses w/ a booster 1-3 yrs later.
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w/c is the ONLY human dz that can be prevented by postexposure vaccination?
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rabies
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what should be done in PEP in rabies infection?
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thorough cleansing of the wound, 5 doses of HDCV should be administered, prompt administration of rabies IG. Treatment before onset of symptoms reduces mortality from 100% to zero.
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what is the genome of rotavirus?
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dsRNA w/ 11 segments & non enveloped
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Rotavirus belongs to w/c family?
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reovirus
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how many serogroups are found in rotavirus? w/c is the MC?
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6 (A-F) w/ group A being the MC
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w/c 2 RNA viruses replicate in the nucleus?
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retro & orthomyxo
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how does rotavirus bind to host cell?
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bind to sialic acid R on the cell via VP4.
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define gene reassortment? seen in w/c virus?
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seen in rotavirus where u have the 11 segments of the virus & u shuffle them to make different combinations.
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in rotavirus, what is the initial infection like?
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it's the most severe & re-infection is possible
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what is the problem that occurs w/ rotavirus?
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dehydration
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talk about immunity w/ rotavirus?
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maternal IgG is not protective but IgA is w/c is found in colostrum. There is no significant immunity against reinfection.
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what is the transmission of rotavirus?
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can survive on surfaces for days & nosocomial outbreaks have been seen.
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this is the MCC of gastroenteritis in children?
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group A rotavirus
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rotavirus affects w/c age group? what season does it peak?
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children 6-24 months w/ winter peak
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What are the 2 genera of picornaviruses?
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Enterovirus & rhinovirus
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What is the genome of picornaviruses?
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+ssRNA, naked icosahedral
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What makes up the enteroviruses?
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Polivirus, coxsackie, echovirus
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What are the 4 major capsid proteins of poliovirus? w/c is associated w/ attachment?
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VP1 is a pentamer, VP2, VP3 are both hexamers, & VP4 is a maturation protein. VP4 is associated w/ attachment
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What do poliovrus bind to?
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ICAM-1
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What will block the poliovirus from getting into the cell?
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Zinc
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Coxsackie B affects w/c part of the body? Coxsackie A?
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Coxsackie B in heart & A in lungs
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What are the two main routes by which enteroviruses such as polio may reach blood? Where virus might go after that?
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Enters via mucosal lining of intestines -->Peyer’s Patches -->Lymph Nodes --> Blood
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How many of poliovirus infections are asymptomatic?
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90% & are limited to the oropharynx & gut
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Paralytic polio occurs how many days after infection? What is the patho?
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3-4 days. The virus spreads from the blood to the anterior horn cells of the SC
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What happens in post polio syndrome?
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Deterioration of nn that are required is the definition of this syndrome
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What are the s/sx of post polio syndrome?
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Mm weakness & paralysis many yrs after the initial infection & recovery
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What has been shown to treat symptoms of PPS?
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Pyridostigmine & seligiline
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What pharmacologic treatment has shown promise in the treatment of fatigue associated w/ PPS?
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Amantadine, deprenyl & mestinon
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What viruses can cause viral meningitis?
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Mumps, measles, enteroviruses (coxsackie A & B, poliovirus) & herpes simplex virus
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What is the IP of viral meningitis?
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Up to 3 wks
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Viral meningitis can be transmitted how?
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Cough, sneezing & poor hygiene & is found in sewage polluted water
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Where do enteroviruses replicate?
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cytoplasm
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what can remove the envelope of viruses?
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alcohol
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w/c of the hepatitis viruses is considered a retrovirus?
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hep B
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what 3 enzymes are found in hep B?
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reverse transcriptase, DNA polymerase, & RNase H
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w/c of the following hepatitis viruses is a DNA virus?
a) hep A b) hep B c) hep C d) hep D e) hep B & C |
B) hep B is the only hepatitis DNA virus. All others are RNA viruses
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hep C belongs to w/c family?
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flavivirus
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what is the genome of hep C?
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+ssRNA & enveloped
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how is hep C transmitted?
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blood transfusions, IV drug users, & sexually
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