Virology Flashcards by Karen Bianca Espinola

Attachment to host cell receptors

Surface proteins

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Nucleic acid genome + capsid =

Nucleocapsid

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For replication

DNA or RNA polymerases

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Interaction between nucleocapsid and envelope

Matrix protein

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Evasion of host defenses

Antigenic (serotypic) variants

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Lipid membrane derived from host cell

Viral envelope

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Viral envelope is acquired as the virus exits from the cell in a process called

Budding

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All enveloped viruses acquire their envelope from plasma membrane EXCEPT

Herpesvirus

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True or False: Enveloped viruses are less stable and more easily inactivated

True

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Naked Viruses

Calici
Picorna
Reo

Parvo
Adeno
Papilloma
Polyoma

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Purified nucleic acids of most dsDNA and (+) strand genome ssRNA viruses are ________?

Infectious

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dsDNA of Poxviruses and HBV

Not infectious

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Naked nucleic acids of (-) strand ssRNA and dsRNA viruses are _____?

Not infectious

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Infectious particles composed entirely of protein which cause transmissible spongiform encephalopathies

Prions

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Non-pathogenic prions

Alpha helix

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Pathogenic prions

Beta-pleated sheet

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All viruses are haploid EXCEPT

Retroviruses

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Segmented Genome Viruses

Bunyaviruses
Orthomyxoviruses
Arenaviruses
Reoviruses

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Negative strand RNA viruses

Arenaviruses
Bunyaviruses
Paramyxoviruses
Orthomyxoviruses
Filoviruses
Rhabdoviruses

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Causes epidemics

Genomic reassortment

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One virus produces a protein that can be used by another virus

Complementation

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Two different viruses infect the same cell

Phenotypic mixing

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Viral Growth Curve: A single virus particle infects a cell

Phase 0: Entry

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Viral Growth Curve: Virus decreases in number but continues to function

Phase 1: Decline

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Viral Growth Curve: No virus is detectable inside the cell

Phase 2: Eclipse Period

Viral Growth Curve: Dramatic increase in amount of detectable viruses

Phase 3: Rise Period

Viral Growth Curve: Amount of detectable viruses reaches a plateau

Phase 4: Latent Period

Viral Growth Curve: Marked derangement of cell function leading to lysis and cell death; Remarkable amplification in number of viral particles

Phase 5: Cytopathic Effect

Visual or functional change in infected cells

Cytopathic effect

Oncogenic viruses induce transformation and unrestrained growth

Malignant transformation

Infected cells appear normal, but are producing large numbers of progeny viruses

Commensal symbiosis

Bind cytokines and block their ability to interact with receptors on their intended targets

Cytokine decoys

Reduce the expression of antigen presenting cells and inactivate complement

Virokines

Produce virus for long periods of time; Can serve as a source of infection for others

Carrier state

Not producing virus at the present but can be reactivated at a subsequent time

Latent infections

Long incubation period, often measured in years

Slow virus infections

Attachment of RBCs to surface of infected cells

Hemadsorption

Interference with CPE by another virus

Interference

Finding antibody in one who previously had none

Seroconversion

Can be used to diagnose current infection

Presence of IgM

Cannot be used to diagnose current infection; Detect past or chronic infection

Presence of IgG

Gold Standard in Viral diagnosis

Presence of viral DNA or RNA

Induce humoral and cell-mediated immunity but may revert to virulence on rare occasions; Dangerous to give to immunocompromised patients or their close contacts

Live-attenuated Vaccines

The only live-attenuated vaccine that can be given to HIV (+) patients

MMR

Live-attenuated Vaccines

Yellow fever Varicella zoster Sabin's Polio MMR

Induce only humoral immunity but are stable

Killed vaccines

Killed Vaccines

Rabies Influenza Polio (Salk's) Hepatitis A

Recombinant Vaccines (Synthetic)

``` Hepatitis B (recombinant HBsAg) HPV (types 6,11,16,18) ```

DNA viruses

``` Hepadna Herpes Adeno Pox Parvo Polyoma Papilloma ```

All DNA viruses have double-stranded DNA EXCEPT

Parvovirus (single-stranded)

All DNA viruses have linear DNA EXCEPT

Papilloma Polyoma Hepadna

All DNA viruses are icosahedral EXCEPT

Poxvirus

All DNA viruses replicate in the nucleus EXCEPT

Poxvirus

Mode of Transmission: Parvovirus B19

Respiratory | Transplacental

Mode of Transmission: Adenovirus

Respiratory | Fecal-oral

Mode of Transmission: Human Papillomavirus

Sexual | Skin contact

Naked virus with icosahedral symmetry; Single stranded DNA genome; One serotype; Transmission: respiratory droplets and transplacental

Parvovirus B19

Bright red cheeks (slapped cheeks) with fever, coryza and sore throat

Erythema infectiosum (Fifth Disease)

Transient but severe aplastic anemia in children; Sickle cell anemia, Thalassemia, Spherocytosis

Aplastic Crisis

Pancytopenia in immunodeficient patients

Chronic B19 Infection

Naked viruses with double-stranded linear DNA and an icosahedral nucleocapsid; Only virus with fiber; 41 antigenic types; Transmission: aerosol droplet, fecal-oral, direct contact

Adenovirus

Spectrum of Disease of Adenovirus: URT

Pharyngitis Conjunctivitis Coryza

Spectrum of Disease of Adenovirus: LRT

Bronchitis | Atypical Pneumonia

Spectrum of Disease of Adenovirus: GIT

Acute Gastroenteritis

Spectrum of Disease of Adenovirus: GUT

Hemorrhagic cystitis (Cowdry type B intranuclear inclusions)

Most common cause of Pediatric Viral Gastroenteritis?

Rotavirus

Naked viruses with double-stranded circular DNA and an icosahedral nucleocapsid; at least 100 types; Transmission: direct contact or sexually

Human Papilloma Virus

Infect squamous cells and induce formation of cytoplasmic vacuole

Koilocytes

Encode proteins that inactivate tumor suppressor genes

Genes E6 and E7

Skin and plantar warts

HPV 1-4

Genital warts and respiratory tract papillomas; Most common viral STD

HPV 6-11

Carcinoma of cervix, penis, and anus

HPV 16, 18, 31, 33

Gold Standard for diagnosis of HPV

PCR

Treatment for Genital warts

Podophyllin

Treatment for Skin warts

Liquid nitrogen

Treatment for Plantar warts

Salicylic acid

Only causes disease in immunocompromised hosts; Causes progressive multifocal leukoencephalopathy (PML) in pts with AIDS

JC Polyoma Virus

Most common Demyelinating disease

Multiple sclerosis

Only causes disease in immunocompromised hosts; Causes hemorrhagic cystitis and nephropathy in patients with solid organ and bone marrow transplants

BK Polyoma Virus

Most common cause of Adult Viral Gastroenteritis?

Norwalkvirus

Herpes Viruses

CMV HSV EBV VZV

Enveloped virus with icosahedral nucleocapsid and linear double-stranded DNA; Multinucleated giant cells on Tzanck smear; Large, pink to purple intranuclear inclusions (Cowdry type A)

Herpes Simplex Viruses

Transmission of HSV 1

Saliva or direct

Transmission of HSV 2

Sexual or transvaginal

Site of latency of HSV 1

Trigeminal ganglia

Site of latency HSV 2

Lumbosacral ganglia

Spectrum of Disease of HSV 1

``` Gingivostomatitis Herpes labialis (lips) Keratoconjunctivitis Temporal lobe encephalitis Herpetic whitlow (fingers) Herpes gladiatorum (trunk) ```

Spectrum of Disease of HSV 2

Genital herpes Neonatal herpes Aseptic meningitis

DOC of HSV

Acyclovir

Enveloped virus with icosahedral nucleocapsid and linear double-stranded DNA; Transmission: Respiratory droplets and by direct contact with lesions; Multinucleated giant cells with intranuclear inclusions

Varicella zoster virus

Incubation period: 14-21 days; Vesicular centrifugal rash (dewdrop on a rose petal appearance); Complication: pneumonia, encephalitis, Reye's Syndrome

Varicella

Reye's Syndrome

``` Fever Vomiting Fatty liver Kidney swelling Brain swelling ```

Uses of Aspirin in Pediatric Diseases

Kawasaki ARF JRA

Painful vesicles along dermatomal distribution; Debilitating pain (Postherpetic neuralgia)

Zoster

Involvement of geniculate ganglion causes facial nerve paralysis

Ramsay Hunt Syndrome

Treatment of VZV

Acyclovir

Enveloped virus with icosahedral nucleocapsid and linear dsDNA; Cultured in shell tubes; Negative heterophil test; Transmission: human body fluids, across the placenta, organ transplantation; Giant cells with owl's-eye nuclear inclusions

Cytomegalovirus

Most common cause of Congenital abnormalities; Microcephaly, seizures, deafness, jaundice, purpura; Most common when mother infected in 1st trimester

Congenital CMV infection

Fever, lethargy, and abnormal lymphocytes in peripheral blood smears

Heterophil-negative Mononucleosis

Pneumonitis, Hepatitis, colitis, retinitis in immunocompromised patients

Systemic CMV infections

DOC of CMV

Ganciclovir (CMV is largely resistant to acyclovir)

Enveloped virus with icosahedral nucleocapsid and linear ds-DNA; Transmission: saliva; Infects mainly lymphoid cells, primarily B lymphocytes; Elicits EBV-specific antibodies and non-specific heterophil antibodies

Epstein-Barr Virus

"Kissing disease"; Fever, sore throat, lymphadenopathy, and splenomegaly; Splenic rupture is a rare complication

Infectious mononucleosis

Malignancies associated with EBV

Burkitt's Lymphoma in African people B cell Lymphomas Nasopharyngeal carcinoma in Chinese people Hairy leukoplakia in AIDS patients

Malignancy of vascular endothelial cells; Skin lesions: dark purple, flat to nodular, and often appear at multiple sites

Kaposi's Sarcoma (Human Herpesvirus - 8)

Only disease that has been eradicated from the face of the earth; Largest viruses; Brick-shaped poxvirus containing linear dsDNA; Transmission: aerosol or contact; Prodrome of fever and malaise followed by centrifugal rash

Smallpox (Variola virus)

Intracytoplasmic eosinophilic inclusions of Variola virus

Guarnieri bodies

Pinkish, papular skin lesions with an umbilicated center; Transmission: direct contact

Molluscum contagiosum

Intracytoplasmic eosinophilic inclusions of Molluscum contagiosum

Henderson-Peterson bodies

Treatment of Molluscum contagiosum

Cifodovir

Enveloped virus with incomplete circular double-stranded DNA; Transmission: blood, during birth, sexual

Hepatitis B virus

HBsAg

Surface antigen

HBcAg

Core antigen

HBeAg; marker of viral replication

E antigen

IgM HBcAg

Acute infection

IgG HBcAg

Chronic infection

Only DNA virus that produces DNA by reverse transcription with mRNA as the template; No cytopathic effect; Incubation period: 10-12 weeks; Fever, anorexia, jaundice, dark urine, pale feces, elevated transaminase levels

HBV

HBV associated with autoimmune vasculitides

Polyarteritis Nodosa (PAN)

Associated malignancy with HBV

Hepatocellular carcinoma

HBV Complication: Functional renal failure without renal pathology

Hepatorenal Syndrome

HBV Complication: Vascular dilatations cause overperfusion relative to ventilation, leading to VQ Mismatch and Hypoxemia

Hepatopulmonary Syndrome

Treatment of HBV

Interferon-alpha | Lamivudine

All RNA viruses have single-stranded RNA EXCEPT

Reovirus | Rotavirus

All RNA viruses replicate in the cytoplasm EXCEPT

Influenza | Retrovirus

Picornaviridae

``` Poliovirus Echovirus Rhinovirus Coxsackievirus Hepatitis A virus ```

Naked nucleocapsid with single-stranded, positive polarity RNA; Oral-fecal transmission; replicates in motor neurons in anterior horn of spinal cord causing paralysis

Poliovirus

Most common clinical form of Poliovirus; Mild, febrile illness with headache, sore throat, nausea, and vomiting

Abortive Poliomyelitis

Aseptic meningitis of Poliovirus

Nonparalytic Poliomyelitis

Flaccid paralysis; Permanent motor nerve damage; Most severe

Paralytic Poliomyelitis

Intranuclear inclusions of Poliovirus

Cowdry Type B

Naked nucleocapsid with single stranded, positive polarity RNA; Transmission: oral-fecal

Coxsackie virus

Fever, sore throat, and tender vesicles in oropharynx

Herpangina

Vesicular rash on hands and feet and ulcerations in the mouth

Hand-foot-and-mouth Disease

Fever and severe pleuritic-type chest pain

Pleurodynia

Most common cause; Fever, chest pain, and signs of congestive failure

Myocarditis | Pericarditis

Most common cause of Aseptic Meningitis

Coxsackie Virus

Enteroviruses

Coxsackie virus Poliovirus Echovirus

Called "orphans" because they were not initially associated with any disease; Now known to cause aseptic meningitis, URTI, febrile illness with or without rash, infantile diarrhea, hemorrhagic conjunctivitis; Transmitted by fecal-oral route

Echovirus (Enteric Cytopathic Human Orphan)

Naked nucleocapsid viruses with single-stranded, positive-polarity RNA; More than 100 serotypes; Transmitted by aerosol droplets and hand to nose contact

Rhinovirus (Common colds)

Naked nucleocapsid virus with a ss-positive-RNA; Fecal-oral transmission; Children most frequently infected; Self limited hepatitis; 1 serotype; no antigenic relationship to HBV or other hepatitis

Hepatitis A aka Enterovirus 72

Most important test for HAV

Anti-HAV IgM

Fecal-oral route; No chronic carrier state; No cirrhosis; No hepatocellular carcinoma; high mortality in pregnancy women

Hepatitis E virus

Non enveloped virus with icosahedral nucleocapsid and one piece of single-stranded, positive-polarity RNA; Oral-fecal transmission; Most common cause of nonbacterial diarrhea in adults; sudden onset of vomiting and diarrhea accompanied by fever and abdominal cramping

Viral Gastroenteritis (Norwalk virus)

Enveloped virus with a helical nucleocapsid and segmented, ss-negative RNA; Major antigens are hemagglutin (H) and neuraminidase (N); Respiratory droplet transmission

Influenza virus

Worldwide epidemics (pandemics) each year; Most common cause of respiratory tract infections

Influenza A

Major outbreaks of influenza; Does not lead to pandemic

Influenza B

Mild respiratory tract infections but does not cause outbreaks of influenza

Influenza C

Binds to the cell surface receptor (neuraminic acid, sialic acid) to initiate infection of the cell; The target of neutralizing antibody; Infective

Hemagglutinin

Cleaves neuraminic acid (sialic acid) to release progeny virus from the infected cell; Also degrades the protective layer of mucus in the respiratory tract which enhances access to the respiratory epithelial cells

Neuraminidase

Major changes based on the reassortment of segment of the genome RNA

Antigenic Shifts (Pandemics)

Minor changes based on mutations in the genome RNA

Antigenic Drifts

DOC of Influenza

Oseltamivir or Zanamivir | Amantadine or Rimantadine for Influenza A only

Paramyxoviruses

Parainfluenza RSV Measles Mumps

Enveloped virus with helical nucleocapsid and one piece of single stranded, negative polarity RNA; Respiratory droplet transmission

Measles virus

Multinucleated giant cells of Measles virus

Warthin-Finkeldey bodies

Bright red lesions with a white, central dot on buccal mucosa; Pathognomonic

Koplik's spots

Complications of Measles virus

Encephalitis Pneumonia Subacute sclerosing panencephalitis (SSPE) or Damson Disease

Cardinal manifestations of Measles

Cough Coryza Conjunctivitis Koplik spots

Enveloped virus with a helical nucleocapsid and one piece of single-stranded, negative-polarity RNA; Respiratory droplet transmission; initially infects URT; tender swelling of parotid glands (parotitis)

Mumps virus

Most common benign Parotid Tumor

Pleomorphic adenoma

Surface spikes (fusion proteins); Causes cells to fuse, forming mutinicleated giant cells (syncytia), which give rise to the name of the virus; human host

Respiratory Syncitial Virus

Most important cause of Pneumonia and Bronchiolitis in infants; Severe disease in infants due to immunologic cross reaction with maternal antibodies

RSV pneumonia

Treatment of RSV Pneumonia

Ribavirin

Characterized by inspiratory stridor, cough and hoarseness; Steeple sign on x-ray

Laryngotracheobronchitis (Croup)

Treatment of Croup

Racemic Epinephrine

Bullet-shaped enveloped virus with helical nucleocapsid and one piece of single-stranded, negative-polarity RNA; Animal reservoir; Transmission: animal bite

Rabies virus

Intracytoplasmic histologic presentation

Negri bodies

WHO Guidelines for Post Exposure Prophylaxis: Category I

No treatment

WHO Guidelines for Post Exposure Prophylaxis: Category II

Vaccine

WHO Guidelines for Post Exposure Prophylaxis: Category III

Vaccine + Immunoglobulin

Enveloped virus with helical nucleocapsid and one piece of single-stranded, Positive-polarity RNA; Prominent club-shaped spikes form a "corona"; 2 serotypes; respiratory droplet transmission

Coronavirus (Common colds)

Atypical pneumonia rapidly progressing to ARDS; Virus binds to ACE-2 receptor; Chest x-ray: non-cavitary "ground-glass" infiltrates

Severe Acute Respiratory Syndrome (SARS)

Enveloped virus with icosahedral nucleocapsid and one piece of single-stranded, positive-polarity RNA; 4 serotypes; transmitted by Aedes aegypti; Diagnosed using dengue IgM; Leukopenia, Thrombocytopenia, increased hematocrit

Dengue virus

Influenza-like syndrome with maculopapular rash and severe pains in muscles and joints

Breakbone Fever

Enveloped virus with one piece of single-stranded, positive-polarity RNA; hypervariable region in envelope glycoprotein; 6 serotypes; Most prevalent blood-borne pathogen

Hepatitis C virus

Replication of HCV in liver is enhanced by

Liver-specific micro-RNA

HCV is the main cause of

Essential mixed cryoglobulinemia

Treatment of Acute Hepatitis C

Interferon

Treatment of Chronic Hepatitis

Peg-interferon and Ribavirin

Most common indication for _____ for severe cirrhosis

Liver Transplantation

Enveloped virus with an icosahedral nucleocapsid and one ss-positive-RNA; Respiratory droplet or transplacental transmission

Rubella Virus

Incubation period: 14-21 days; Prodrome followed by 3-day maculopapular rash and posterior auricular LAD; immune-complex polyarthritis in adults

German Measles

Infected during the 1st trimester; Associated abnormalities: patent ductus arteriosus, congenital cataracts, sensorineural deafness, mental retardation

Congenital Rubella Syndrome

5 Bs of Congenital Rubella Syndrome

``` Bulag (cataracts) Bingi (sensorineural deafness) Bobo (mental retardation) Butas ang puso (PDA) Blue berry muffin baby ```

Distinguished from all other RNA viruses by the presence of an unusual enzyme, reverse transcriptase which converts a single-stranded RNA viral genome into double-stranded viral DNA

Retroviridae

Enveloped virus with two copies (diploid) of a single-stranded, positive-polarity RNA genome; most complex of the known retroviruses; many serotypes

Human Immunodeficiency Virus

Fusion protein of HIV; Mediates the fusion of the viral envelope with the cell membrane at the time of infection

gp41

Attachment protein of HIV; Interacts with CD4 receptor; Gene mutates rapidly (many antigenic variants); High mutation rate may be due to lack of an editing function in the reverse transcriptase

gp120

Capsid protein of HIV; Group-specific antigen, located in the core, not known to vary, antibodies against p24 do not neutralize HIV infectivity but serve as important serologic markers of infection

p24

Outer matrix protein of HIV

p17

Nucleoprotein of HIV

Gene that encodes p24, p7, p17

gag Gene

Gene that encodes reverse transcriptase, protease, integrase

pol Gene

Gene that encodes gp120 and gp41

env Gene

Most immunogenic region of gp120

V3 loop

Activation of transcription of viral genes

tat Gene

Transport of late mRNAs to cytoplasm

rev Gene

Decreases CD4 and Class I MHC proteins

nef Gene

Enhances hypermutation

vif Gene

Transport in non-dividing cells

vpr Gene

Enhances virion release

vpu Gene

Preferentially infects and kills helper (CD4+) T lymphocytes; Loss of cell-mediates immunity; High probability of opportunistic infections; Main immune response consists of cytotoxic (CD8+) lymphocytes

HIV

Stages of HIV Infection: HIV acquired through sexual intercourse, blood, or perinatally

Phase 0: Infection

Stages of HIV Infection: Rapid biral replication but HIV test is negative

Phase 1: Window Period

Stages of HIV Infection: Peak of viral load, positive HIV test, mild flu-like illness, lasting 1-2 weeks

Phase 2: Seroconversion

Stages of HIV Infection: Asymptomatic, CD4 goes down, lasts 1-15 years

Phase 3: Latent Period

Stages of HIV Infection: CD4 500-200, lasts 5 years, mild mucocutaneous, dermatologic and hematologic illness

Phase 4: Early Symptomatic

Stages of HIV Infection: CD4 <200 lasts 2 years, AIDS-defining illnesses develop

Phase 5: AIDS

AIDS-defining Illness: CD4 <500

M. tuberculosis (dissiminated tuberculosis) HSV (HSV esophagitis) C. albicans (esophageal candidiasis) HHV-8 (Kaposi's sarcoma)

AIDS-defining Illness: CD4 <200

``` P. jiroveci (PCP pneumonia) T. gondii (cerebral toxoplasmosis) C. neoformans (meningoencephalitis) C. immitis (coccidiomycosis) C. parvum (chronic diarrhea) ```

AIDS-defining Illness: CD4 <50

M. avium (invasive pulmonary disease) H. capsulatum (histoplasmosis) CMV (CMV retinitis)

Screening test for HIV

ELISA

Confirmatory test for HIV (For Definitive Diagnosis)

Western blot Analysis

Used for Prognostication of HIV

PCR

Treatment of HIV

Highly active antiretroviral therapy (HAART)

Retrovirus causing Adult T-cell leukemia and HTLV-associated myelopathy; HP: malignant T cell with flower-shape nucleus

Human T-cell Lymphotropic Virus (HTLV)

Thread-like viruses; Longest viruses; Outbreak of hemorrhagic fever; 100% mortality

Ebola Virus (Ebola Hemorrhagic Fever)

Flavivirus; Bird-mosquito-man cycle; Initial self limited febrile illness with progression to neuroinvasive disease

West Nile Virus (West Nile Fever)

Membrane of flavivirus; Most common cause of epidemic encephalitis; most prevalent in SEA; Transmitted by Culex mosquitoes; Thalamic infarcts on CT Scan

Japanese B Virus (Japanese B Encephalitis)

Virology Flashcards

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