Viruses Flashcards
Influenza virus (A/B/C)
Family: Orthomyxovirus (ss enveloped negative RNA)
2 Glycoprotein spikes: Hemagglutinin (H1, H2, H3) and Neuraminidase (N1, N2)
Host: humans
Incubation: 2 days
Transmission: Direct droplet spread
Entry point: Upper respiratory tract
Symptoms: abrupt onset, fever, malaise, headache, chills FACTS
Complications: Pneumonia, Bacterial superinfection, Reye’s syndrome
Diagnostic: nose and through swabs for cell culture or Rapid Flu (tests for antigen), serodiagnosis.
Prevention: Antivirals, Vaccines (killed and live attenuated)
Coronavirus
Family :Picornavirus (ss naked, + stranded RNA)/coronavirus Host: human Entry point: upper respiratory tract Transmission: respiratory droplet Incubation: 2-4 days Symptoms: Sneezing, nasal discharge, cough headache, sore throat Duration: 1 week Diagnostics: none Prevention: None
Rubella (German Measles)
Family: Togavirus (ss enveloped positive RNA)
Host: humans
Transmission: respiratory droplets, transplacental
serotype: 1
Entry Point: URT
Incubation: 14-21 days
Symptoms: low grade fever, lymphadenopathy, w/in 24 hrs macular rash and petechial rash on soft palate
Duration: 1-3 days
Complications: Arthritis, Enchepalitis, *fetal damage (heart disease, deafness, blindness)
Diagnostics: Viral culture, RT-PCR, Serology
Prevention: Live vaccine (MMR)
Flavivirus
ssRNA
enveloped capsid
Hepatitis C, west nile virus
Measles (Rubeola)
Family: Paramyxovirus (ss enveloped negative RNA)
Morbillivirus (infectious agent)
Serotype: 1
Host: humans
Transmission: person to person contact, respiratory droplet
Entry Point: Upper respiratory tract
Incubation: 7-18 days
Symptoms: fever, cough, coryza, conjunctivitis. Then Koplik spots (inside of cheek). Then rash to the head, trunk, then extremities
Complications: Pneumonia, enchephalitis, bleeding disorders, bacterial superinfection
Diagnostics: Viral culture, RT-PCR, serology
Prevention: Live vaccine, immune serum globulin
Rabies Encephalitis
Family: Rhabidovirus (ss negative enveloped RNA)
Transmission: usually a dog bite (infected secretions)
Host: all mammals
Entry Point: multiples in muscle cells, then travels to CNS then replicates to brain cells
Incubation: 10 days - 1 year
Symptoms: affects the CNS, foaming of the mouth, seizures, hallucinations. survival after being symptomatic is 4 days
Diagnostics: RT-PCR, serology
Prevention: pre exposure- inactivated vaccine, post exposure- human hyperimmune anti rabies globulin plus rabies vaccine
HIV
Family: Retrovirus (ss postive enveloped RNA)
LATENT
3 essential enzymes for replication: reverse transcriptase, Protease, integrates.
2 viral glycoproteins: gp120 and gp41
Transmission: requires intimate contact with infecting source, perinatal
Symptoms: acute (fever, malaise, maculopapular rash, highly contagious), latent (asymptomatic but contagious), AIDS (decline in CD4 cells, immunocompromised)
Diagnostics: ELISA, HIV antigen test, HIV RNA viral load assay
Prevention: appropriate screening, avoid exposure, antiretrovirals, pre and post exposure prophylaxis.
Rotavirus
Family: Reovirus (ds naked DNA) Host: humans and animals Transmission: fecal oral, cooler months Serotypes: 5 Incubation: 1-3 days, Symptoms: vomiting then hours later watery brown stools Complications: dehydration Diagnostics: ELISA, PCR, serology Prevention: live oral vaccine good hygiene
Norwalk virus
Family: Calcivirus (ss Naked, positive RNA)
Infectious agent: Norovirus
Transmission: fecal oral, consumption of contaminated food or water or uncooked shellfish
Serotypes: 4
Incubation: 10-51 hours
Symptoms: abrupt onset of vomiting and diarrhea (usually at the same time)
Complication: dehydration
Diagnostics: RT-PCR, enzyme immunoassay
Prevention: hygiene
Hepatitis E
Family: Hepevirus (ss, positive, naked RNA)
Transmission: fecal oral
Host: humans
Incubation: 40 days
Symptoms: Jaundice, anorexia, nausea, fever, hepatomegaly, vomiting
Complications: when symptomatic it can fatal (especially when pregnant)
Diagnostics: Serology
Prevention: None
Varicella Zoster-chicken pox
Herpesvirus (ds enveloped DNA)
LATENT INFECTIONS
Host: Humans
Transmission: respiratory droplet and skin contact with lesion
Serotype: 1
Entry point: Upper respiratory tract
Incubation: 14-21 days
Symptoms: Prodromes- fever, malaise, papulovesicular rash in crops on trunk then goes to head and extremities (may see 3 different stages of the rash)
Complications: Varicella Pneumonia, enchephilits, Reye’s syndrome
Diagnostics: Tzanck smear, Viral culture, PCR, serology, direct fluorescent antibody
Prevention: Antivirals (Acyclovir), Live Vaccines, Varicella zoster immune globulin
Poxvirus
dsDNA
Enveloped capsid
Smallpox, Molluscum contagiosum
Adenovirus
dsDNA
Naked
Respiratory diseases, Gastroenteritis
Fifth Disease
Family: Parvovirus B19 (ss DNA naked)
Host: humans
Transmission: respiratory, blood products, direct contact or fomites, vertical
Incubation 4-12 days
Symptoms: Fever, malaise, pruritus, “slap cheek rash”, 1-2 days later rash on arms and legs
Duration: 1-2 weeks
Complications: high risk to fetus, nephritis, encephalitis, hepatitis, thrombocytopenia
Diagnostics: NAAT, serology
Prevention: immunoglobin, NO VACCINE
Viral Pharyngitis
Family: Multiple (enveloped and naked)
Host: Humans
Entry point: upper respiratory
Transmission: droplet, direct contact, fomites
Symptoms: Sore throat, headache, malaise, hoarseness, ear pain, cough
Diagnostics: RADT, throat culture
Prevention: hand washing/ good hygiene
MAIN THING IS RULE OUT BACTERIAL INFECTION
Varicella Zoster-Shingles
Herpesvirus (ds enveloped DNA)
LATENT INFECTION
Transmission: respiratory droplet and skin contact with lesion
Entry point: Upper respiratory tract
Symptoms: Painful vesicles along the course of a sensory nerve of the head or drunk (follows dermatome)
Diagnostics: Tzanck smear, Viral culture, PCR, serology, direct fluorescent antibody
Prevention: Antivirals, Live Vaccines, Varicella zoster immune globulin
Complications: posteherpetic neuralgia, pneumonia
Roseola (Exanthem Subitum)
Family: Herpesvirus (ds enveloped DNA) Human herpesvirus 6 or 7 Transmission: saliva Symptoms: fever x 3 days, then faint maculopapular rash Diagnostics: serology and PCR Prevention:
Mumps Virus
Family: Paramyxovirus (ss enveloped negative RNA)
Host: human
Transmission: respiratory droplet or direct contact or fomites
Serotype: 1
Entry Point: upper respiratory tract
Incubation: 18-21 days
Symptoms: fever, malaise, anorexia, tender salivary gland
Duration: 1 week
Complications: orchitis is post pubertal males, meningitis
Diagnostics: viral culture, RT-PCR, serology
Prevention: Live vaccine (MMR)
Hepatitis A
Family: Picornavirus (ss positive naked RNA)
Transmission: fecal oral, contaminated food and water
Serotypes: 1
Host: humans and primates
Incubation: 15-45 days
Symptoms: RUQ pain, fever, anorexia, clay colored stools, hepatomegaly
Duration- days- weeks
Diagnostics: serology
Prevention: avoidance of exposure, active immunization, passive immunity
Hepatitis B
Family: Hepadenovirus (ds enveloped DNA
Transmission: Vertical, sexual contact, parentally
Serotypes: 4
Host: humans
Incubation: 10 weeks
Symptoms:RUQ pain, jaundice, grey colored stools, rash
Duration: several months
Complications: liver failure, fulminant hepatitis, chronic hepatitis, HCC
Diagnostics: serology
Prevention: recombinant vaccine, Hep B immune globulin, reverse transcriptase inhibitors
Hepatitis D (HDV)
Family: Deltavirus (ss Enveloped RNA)
Transmission: needs Hep B surface antigens. high risk for injunction drug users
Symptoms: looks like HBV or HAV
Complications: chronic cirrosis, progressive liver disease
Diagnostics: serology
Prevention: recombinant vaccine, Hep B immune globulin, reverse transcriptase inhibitors
Hepatitis C
Family: Flavivirus (ss positive enveloped RNA)
Transmission: parenterally, sexually transmitted
Host: humans
Incubations: 6-12 weeks
Symptoms: usually asymptomatic
Complications: cirrhosis, increased HCC risk
Diagnostics: ELISA, RIBA, RT-PCR
Prevention: no active and passive immunity, Antiviral medications
Enterovirus
Family: Picornavirus (naked ss positive RNA)
Transmission: fecal oral, infects GI and upper respiratory tract
Incubation: 2-10 days
Groups: Poliovirus (paralytic) , Coxsackievirus (Group A- hand foot mouth disease, Group B- myocarditis, pleurodynia), Echovirus (ascetic meningitis, URI)
Diagnostics: RT-PCR
Prevention: inactivated poliovirus vaccine
Arboviruses
Family: 1. Togavirus (ss positive enveloped RNA). 2. Flavivirus (ss positive enveloped RNA), 3. Bunyavirus (ss negative enveloped RNA)
Transmission: infected blood sucking insects
Symptoms: acute febrile illness, encephalitis, meningitis
Prevention: immunization for yellow fever, tick borne, japanese b enchapalitis.
What makes up a virion?
internal core (DNA) and protein coat
Characteristics of envelopes
lipid bilayer, more sensitive to heat/drying/solvents, transmitted by direct contact or respiratory droplets
Transcription
changing DNA (from negative strand) to mRNA to allow for translation
Translation
process changing mRNA to protein
Reverse Transcriptase
RNA from Retrovirus converted to double stranded DNA, transcribed to mRNA
Prions
no DNA, composed entirely of misconfigured proteins, causes spongiform encephalititis
Penetration/Entry?
Naked viruses engulfed, enveloped undergo fusion
Prevention
Active immunity: attenuated live virus (long lasting), killed virus, subunit vaccines (purified viral proteins)
Passive Immunity: antibodies in immune globulins
Herd immunity
Diagnostic Procedures
Serology: acute &convalescent samples needed-takes long time
Viral antigen detection (ELISA)
Viral nucleic acid detection (PCR)
