- Sense RNA Viruses Flashcards
What type of genome characterizes -RNA viruses like Paramyxovirus, Orthomyxovirus, and Rhabdovirus?
Single-stranded, negative-sense RNA
Which structure surrounds the genome of Paramyxoviridae viruses?
An envelope surrounding a helical nucleocapsid
How does Paramyxovirus enter the host cell?
Through fusion with the host cell plasma membrane
What unique replication characteristic is associated with Orthomyxoviridae?
Genome replication occurs in the host cell nucleus
What enzyme is necessary for the transcription of negative-sense RNA to positive-sense RNA?
RNA-dependent RNA polymerase
Which disease is commonly caused by Paramyxovirus?
Measles and mumps
What is the primary mode of transmission for Paramyxoviruses?
Respiratory droplets
What immune evasion strategy is employed by Paramyxoviruses?
Formation of syncytia to avoid immune detection
Which diagnostic method is commonly used to identify Paramyxovirus infections?
PCR and antigen detection tests
Which antiviral drug class is used to treat some Orthomyxovirus infections?
Neuraminidase inhibitors like oseltamivir (Tamiflu)
What structure characterizes Rhabdoviruses like the rabies virus?
A bullet-shaped, enveloped virion with a helical capsid
How is rabies virus primarily transmitted?
Through animal bites and saliva
What tissue tropism is associated with rabies virus?
Central nervous system (CNS)
Which immune evasion technique is utilized by Rhabdoviruses?
Avoiding immune detection by rapid CNS entry
What diagnostic technique is critical for rabies identification postmortem?
Direct fluorescent antibody (DFA) testing on brain tissue
What is the primary treatment/prevention method for rabies virus?
Post-exposure prophylaxis with rabies vaccine and immunoglobulin
What feature distinguishes Bunyaviridae’s genome?
Segmented, negative-sense RNA genome
What vector commonly transmits Bunyavirus?
Mosquitoes or other arthropods
Which disease is associated with Hantavirus, a Bunyavirus?
Hantavirus pulmonary syndrome
How does Arenavirus typically evade the immune system?
By establishing chronic infections with minimal host immune activation
What is a major disease associated with Arenavirus?
Lassa fever
How is Lassa virus transmitted to humans?
Through contact with rodent excreta
What is the typical clinical presentation for Lassa fever?
Fever, sore throat, and hemorrhagic symptoms
What type of immunity is critical in controlling Paramyxovirus infections?
Cell-mediated immunity
What is the mechanism of action for neuraminidase inhibitors against Orthomyxovirus?
Blocking virus release from infected cells
What is a defining feature of Arenaviruses’ genome?
Ambisense RNA segments
How is Orthomyxovirus spread globally?
Through seasonal influenza epidemics
What clinical tool is essential for diagnosing influenza caused by Orthomyxovirus?
Rapid antigen tests and RT-PCR
How do Bunyaviruses affect the host’s cellular machinery?
By causing cell lysis and cytokine release
What is a preventative strategy for Bunyavirus-related diseases?
Vector control and reducing exposure to known hosts
How does Paramyxovirus cause cell damage in the respiratory tract?
By inducing syncytia formation, leading to cell fusion and damage
What specific proteins are found on the surface of Orthomyxoviruses?
Hemagglutinin (HA) and neuraminidase (NA)
What distinguishes Orthomyxovirus from Paramyxovirus in terms of genome structure?
Orthomyxovirus has a segmented RNA genome, while Paramyxovirus has a non-segmented genome
Which Paramyxovirus protein is critical for viral entry?
Fusion protein (F protein)
What neurological disease can result from a measles virus complication?
Subacute sclerosing panencephalitis (SSPE)
What seasonal pattern is commonly observed in influenza virus outbreaks?
Higher incidence in winter
How does Rhabdovirus avoid antibody recognition during early infection?
By traveling via the peripheral nervous system to the CNS
What immune response is primarily responsible for controlling rabies virus infection?
Neutralizing antibodies post-vaccination
How is Bunyavirus replication uniquely adapted to arthropod hosts?
By replicating efficiently at lower temperatures found in ectothermic hosts
What is a characteristic symptom of Rift Valley fever caused by Bunyavirus?
Hemorrhagic fever
Which Arenavirus is known for causing hemorrhagic fever in South America?
Junin virus
What cellular receptor does Lassa virus use for entry into human cells?
Alpha-dystroglycan
How do Arenaviruses persist in their rodent hosts without causing severe disease?
Through co-evolution, minimizing host immune activation
What is the primary mode of transmission for Hantavirus in humans?
Inhalation of aerosolized rodent excreta
Which symptom is a hallmark of Hantavirus pulmonary syndrome (HPS)?
Severe respiratory distress
How does Orthomyxovirus enter the host cell?
Via receptor-mediated endocytosis and fusion within the endosome
Which diagnostic test is commonly used to confirm Hantavirus infection?
RT-PCR or serology for hantavirus antibodies
What is the function of the viral polymerase complex in Orthomyxovirus?
Transcription of viral RNA into mRNA for protein synthesis
What environmental condition inactivates most Arenaviruses?
Exposure to heat and detergents
Why is early isolation important in managing Lassa fever outbreaks?
To prevent human-to-human transmission in healthcare settings
What is the structural arrangement of the Rhabdovirus genome?
Linear, single-stranded negative-sense RNA
What cell entry strategy is unique to Arenaviruses compared to other RNA viruses?
Utilizing a pH-dependent fusion mechanism in late endosomes
How does immune modulation by Bunyaviruses contribute to pathogenesis?
Through cytokine release, leading to inflammation and tissue damage
What is the role of hemagglutinin in influenza virus infection?
Binding to sialic acid receptors on host cells to initiate entry
How does the immune system typically control Arenavirus infections?
By producing specific antibodies targeting viral proteins
What clinical symptoms are most associated with measles virus infection?
Fever, cough, coryza, conjunctivitis, and a characteristic rash
What immune evasion strategy is employed by Orthomyxovirus to delay immune detection?
Antigenic shift and drift in surface proteins HA and NA
Why are segmented genomes, like that of Bunyaviruses, advantageous for viral evolution?
They allow reassortment, leading to new viral strains
How is the laboratory diagnosis of rabies confirmed in live patients?
Detection of rabies virus RNA or antibodies in saliva or cerebrospinal fluid
What is the prevention strategy for measles in unvaccinated individuals exposed to the virus?
Administration of the measles vaccine or immune globulin post-exposure
