Viro Summary 2 Flashcards
________ and ________ are nonenveloped and contain a double-stranded, segmented RNA genome.
▪︎Reoviruses
▪︎rotaviruses
___________ are the most important cause of diarrheal illness in infants and young children worldwide.
Rotaviruses
Occurs readily with rotaviruses.
Genetic reassortment
Small nonenveloped viruses with a single-stranded, nonsegmented RNA genome
Caliciviruses
_________, a genus of caliciviruses, are the major cause of nonbacterial epidemic gastroenteritis in the world.
Noroviruses
___________ and __________ are transmitted primarily by fecal–oral spread; _________ are associated with foodborne and waterborne outbreaks.
▪︎Rotaviruses
▪︎and noroviruses
▪︎noroviruses
____________________are available that are safe and effective; there is no norovirus vaccine.
Oral live attenuated rotavirus vaccines
Arbovirus diseases fall into three general categories:
▪︎fevers (usually benign),
▪︎encephalitides, and
▪︎hemorrhagic fevers.
Major mosquito-borne diseases are
▪︎yellow fever, ▪︎dengue, ▪︎Japanese B encephalitis, ▪︎West Nile fever, and ▪︎Eastern equine encephalitis
_________________ are antigenically related; all flaviviruses are antigenically related.
All alphaviruses, in the Togaviridae family
Inapparent infections are common with the _____________ and neuroinvasion seldom occurs.
viral encephalitis viruses
Accidental hosts of arbovirus infections and are not essential for the viral life cycles
Humans
Leading cause of arboviral encephalitis in the United States
West Nile virus
Distributed worldwide in tropical regions and is probably the most important mosquito-borne viral disease of humans.
Dengue
A self-limited disease, but dengue hemorrhagic fever and dengue shock syndrome are severe and potentially fatal.
Dengue fever
Occurs with secondary infections in the presence of preexisting antibody from a primary infection by a different viral serotype
Dengue hemorrhagic fever
It often leaves serious sequelae, but yellow fever infections have none
Japanese B encephalitis
Major rodent-borne viral diseases are _______________, __________, and ____________.
▪︎hantavirus infections,
▪︎Lassa fever,
▪︎and South American hemorrhagic fevers
The reservoir hosts for African hemorrhagic fevers, Marburg and Ebola, are suspected to be ______
bats or possibly rodents
________________________ are caused by bunyaviruses (hantaviruses) and arenaviruses (Lassa fever).
Rodent-borne hemorrhagic fevers
__________ of many arbovirus infections involves protection against mosquito or tick bites, mosquito control, wearing of protective clothing, use of repellent chemicals, or avoidance of infested areas
Prevention
__________ are major respiratory pathogens
Influenza viruses
Highly variable antigenically and causes most epidemics and all global pandemics
Influenza type A
Sometimes undergoes antigenic changes and can cause epidemics.
Influenza type B
Antigenically stable.
Influenza type C
Found in aquatic birds, ducks, domestic poultry, pigs, and horses
Influenza A strains
The __________________________ consisting of _________________
▪︎viral genome is single-stranded, negative-sense RNA
▪︎eight separate segments
Surface glycoproteins, ____ and ____, determine influenza virus antigenicity and host immunity
▪︎HA
▪︎NA
Minor antigenic changes in HA and NA, termed __________, occur independently and are caused by accumulation of point mutations.
antigenic drift
A major antigenic change in HA or NA, called __________, results in a new influenza virus subtype and is caused by genetic reassortment of genome segments between human and animal viruses.
antigenic shift
Immunity to influenza is long lived and subtype specific.
Only antibodies to HA and NA are protective.
Cause sporadic human infections but have not acquired the ability for sustained human-to-human transmission.
▪︎Avian influenza A viruses,
▪︎H5N1,
▪︎H7N9, and
▪︎H9N2
Transmitted by contact or large droplets and initiate infections through the respiratory tract.
Paramyxoviruses
The ____________ for paramyxoviruses ______ in the cytoplasm of cells
▪︎entire viral replication cycle
▪︎occurs
Most important cause of lower respiratory tract illness in infants and young children.
Respiratory syncytial virus
____________ occurs most often in infants ages 6 weeks to 6 months.
Serious bronchiolitis or pneumonia
Respiratory pathogens for young children, immunocompromised individuals, and elderly adults. Disease resembles that of respiratory syncytial virus.
Human metapneumoviruses
Cause respiratory illnesses in all ages; most serious disease occurs in infants and young children
Parainfluenza viruses
Preferred method for diagnosis of respiratory virus infections.
Detection of viral RNA or viral antigens
Approved for treatment of respiratory syncytial virus disease in infant
Ribavirin
____________ are common with the respiratory viruses
Reinfections
A systemic disease, with about half of infections causing swelling of the salivary glands. Many infections are asymptomatic
Mumps
A highly infectious, disseminated infection characterized by a rash.
Measles (rubeola)
___________________________________, respiratory syncytial virus, or human metapneumoviruses. Effective vaccines exist for both measles and mumps
No vaccines are available for parainfluenza viruses
______________ and _____________ are animal paramyxoviruses able to infect humans; they cause encephalitis with a high mortality rate. There is no treatment
▪︎Hendra
▪︎and Nipah viruses
Classified as a togavirus but is not transmitted by arthropods. It is the mildest of the common viral exanthems
Rubella (German measles)
During early pregnancy can result in serious harm to the fetus, including fetal death.
Rubella infection
Prevented by childhood vaccination so that women of
childbearing age are immune.
rubella vaccine
Enveloped and contain a genome of single-stranded positive-sense RNA that is the largest genome among RNA viruses.
Coronaviruses
Typically cause common colds
Human coronaviruses
Originated in a nonhuman host caused a worldwide outbreak of SARS in 2003.
novel coronavirus
__________ was first detected in 2012, and can cause severe respiratory disease in some patients.
MERS-CoV
There is ________ and _________ for coronaviruses.
▪︎no proven treatment
▪︎no vaccine
A viral encephalitis that is almost always fatal once symptoms appear. It is caused by an RNA virus classified as a rhabdovirus
Rabies
Humans get infected with ___________ from a rabid animal. The incubation period can range from 1 week to more than a year
rabies by a bite
There are no tests to diagnose rabies infections in humans before disease develops. There is no successful treatment for clinical rabies.
no tests to diagnose
Consists of administration of rabies antibody, rabies vaccine, or both, following a possible exposure
Postexposure prophylaxis
Rare and fatal central nervous system disease caused by measles virus
Subacute sclerosing panencephalitis
Rare, usually fatal, central nervous system disease caused by polyomavirus JC virus in immunosuppressed individuals.
Progressive multifocal leukoencephalopathy
Caused by unconventional agents with properties of infectious protein
prion diseases (transmissible spongiform encephalopathies)
_____________ include kuru, CJD, and variant CJD
Human prion diseases
Very resistant to inactivation, including formaldehyde, boiling, and radiation; they can be inactivated by bleach and autoclaving
Prion agents
Also considered a cancer agent because of the immune suppression associated with infection by the virus
HIV
_________ and _________ are used to explore mechanisms of viral carcinogenesis.
Animal models and cultured cells
Revealed the roles of cellular oncogenes and tumor suppressor genes in cancer and fostered the recognition of the molecular basis of carcinogenesi
Studies with tumor viruses
Establish persistent infections in hosts, with long latent periods between initial infection and tumor appearance.
Tumor viruses
______________ are much more common than virus-related tumor formation
Cancer virus infections
A disease first described in 1981
HIV causes AIDS
Now a worldwide epidemic; more than 35 million people are living with HIV/AIDS.
HIV/AIDS
A lentivirus, a type of retrovirus.
HIV
Derived from primate lentiviruses common in Africa
▪︎HIV-1
▪︎and HIV-2
Transmitted during sexual contact, through parenteral exposure to contaminated blood or blood products, and from mother to child during the perinatal period
HIV
HIV uses ___ as a receptor
CD4
During ____________, there is a high level of HIV replication and a decline in CD4 T lymphocytes.
clinical latency
Develop both humoral and cellular immunity against HIV antigens, but these responses do not clear the infection
HIV-infected persons
Major causes of morbidity and mortality among HIVinfected individuals are _____________ (those rarely seen in immunocompetent people) and ___________.
▪︎opportunistic infections
▪︎neurologic symptoms that usually occur when CD4 T-cell counts fall below 200 cells/μL
Therapy with combinations of antiretroviral drugs can _____________.
turn HIV infection into a chronic disease.
AIDS-defining cancers that occur in untreated infected individuals include __________, _____________ and _____________.
▪︎Kaposi sarcoma,
▪︎cervical cancer,
▪︎and non-Hodgkin lymphoma.
______________ on effective drug therapy are at risk for several non-AIDSdefining cancers, including _____ and ____, ____, and ______________.
▪︎Longer-lived patients
▪︎head and neck,
▪︎liver,
▪︎and oral malignancies
Can be used for prevention of infection.
HIV drugs
