microbio exam 4

viruses!!!!

characteristics of life

organization, homeostasis, growth and metabolism, response to stimuli, heredity, reproduction, evolution, and adaptation

organization

being structurally composed of one or more cells

homeostasis

regulation of an internal environment for stability

growth and metabolism

* increasing in size in all of its parts rather than simply accumulating matter
* performs anabolism and catabolism

anabolism

transformation of energy by converting chemicals and energy into cellular components

catabolism

decomposing organic matter

properties that viruses share with life

* organization
* genetic material
* replicative life cycle
* evolution over time

properties of life that viruses lack

* not comprised of cells
* lack homeostasis
* have no growth or metabolism
* do not respond to stimuli
* cannot reproduce without the use of host cell machinery

virus

non-living obligate intracellular parasite

virion

a virus that is extracellular

genome

* DNA or RNA varies considerably in size and organization
* controls the virus replication strategy

central dogma

antisense DNA → (transcription) → sense RNA (translation) → proteins

sense DNA

* (+)
* non-template strand of DNA
* IS NOT transcribed

antisense DNA

* (-)
* template strand of DNA
* IS transcribed

template strand

strand of DNA that IS transcribed

non-template strand

strand of DNA that IS NOT transcribed

sense RNA

* (+)
* mRNA that IS translated into a protein

antisense RNA

* (-)
* RNA that is a complimentary strand to the translated mRNA

DNA viruses (9)

* Adenovirus
* EBV
* HSV-1
* Parvovirus
* VZV
* CMV
* HPV
* HSV-2
* Variola virus

RNA viruses (23)

* Dengue fever
* Enterovirus
* Hantavirus
* Influenza virus
* Measles virus
* Mumps virus
* Poliovirus
* Rhinovirus
* RSV
* SARS-CoV
* West Nile virus
* Zikavirus
* EBOV
* HAV
* HCV
* MARV
* MERS-CoV
* Norovirus
* Rabies virus
* Rotavirus
* Rubella virus
* SARS-Cov-2
* Yellow Fever virus

retro viruses (2)

* HIV
* HBV

adenovirus

* DNA virus
* causes the common cold

EBV

* DNA virus
* stands for Epstein-Barr virus
* causes 90% of mono cases

HSV-1

* DNA virus
* stands for herpes simplex virus
* causes cold sores

parvovirus

* DNA virus
* causes eczema

VZV

* stands for varicella-zoster virus
* causes chicken pox and shingles

CMV

* DNA virus
* stands for cytomegalovirus
* causes 10% of mono cases

HPV

* DNA virus
* stands for human papillomavirus
* causes STIs and cervical cancer
* family of 170 naked DNA viruses
* most common STI in the world
* vaccine prevents cervical cancer

HSV-2

* DNA virus
* stands for herpes simplex virus
* causes herpes

variola virus

* DNA virus
* causes smallpox

dengue fever

* RNA virus
* causes dengue fever

enterovirus

* RNA virus
* causes viral meningitis

hantavirus

* RNA virus
* causes hemorrhagic fever

influenza virus

* RNA virus
* causes the flu

measles virus

* RNA virus
* causes measles

mumps virus

* RNA virus
* causes mumps

poliovirus

* RNA virus
* causes polio

rhinovirus

* RNA virus
* causes the common cold

RSV

* RNA virus
* stands for respiratory syncytial virus
* causes bronchiolitis and pneumonia

SARS-CoV

* RNA virus
* causes COVID

west nile virus

* RNA virus
* causes fever, headaches, body aches, joint pains, vomiting, diarrhea or rash

zikavirus

* RNA virus
* causes fever, rash, headache, joint pain, red eyes, muscle pain
* in rare cases, it causes birth defects and is linked to guillian-barre syndrome

EBOV

* RNA virus
* stands for ebola virus
* causes ebola

HAV

* RNA virus
* stands for hepatitis-A
* causes liver inflammation and damage

HCV

* RNA virus
* stands for hepatitis-C
* causes liver inflammation and damage; ranges from mild illness to chronic illness

MARV

* RNA virus
* stands for Marburg virus
* causes hemorrhagic fever

MERS-CoV

* RNA virus
* stands for middle east respiratory syndrome coronavirus
* causes COVID symptoms

norovirus

* RNA virus
* causes crew ship virus

rabies virus

* RNA virus
* causes rabies

rotavirus

* RNA virus
* causes diarrhea in kids

rubella virus

* RNA virus
* causes German measles

SARS-CoV-2

* RNA virus
* causes severe, acute COVID symptoms

HIV

* RNA retrovirus
* stands for human immunodeficiency virus
* causes AIDS

HBV

* RNA retrovirus
* stands for hepatitis-B
* causes either acute liver inflammation or chronic liver disease

mutation rate of viruses

high rate because viral genomes have little to no repair mechanisms

capsid

* protein coat protecting the genome
* may carry accessory proteins

accessory proteins

composed of capsomeres and are found in the capsid

capsomeres

composed of protomers and are found in accessory proteins

protomers

the building blocks for capsomeres that are found in accessory proteins

four basic viral shapes

* helical
* spherical
* polyhedral
* complex

helical

* repeated capsomeres that form a filamentous capsid that surround the genome
* can also be referred to as filamentous
* not always strictly helical

examples of helical viruses

* ebola virus
* mumps virus
* tobacco mosaic virus

spherical

* has a spherical capsid and/or envelope
* capsid holds the spherical shape even if the envelope does not

examples of spherical viruses

* influenza virus
* COVID

polyhedral

* capsomeres that form 20 faces, 12 vertices, and 30 edges
* also referred to as icosahedral, cubic, regular or isometric

examples of polyhedral viruses

* adenovirus
* herpesvirus
* mastadenovirus

complex

a “catch-all” group for viruses with no real pattern, or have a mixture of several shapes

examples of complex viruses

* t4 bacteriophage
* variola virus
* rabies virus

envelope

* host-derived lipid membrane that contains both the host and viral proteins
* not found in every single virus
* doesn’t determine the shape of the virus

naked virus

virus without an envelope

attachment proteins

* also called spike proteins
* glycoproteins that recognize one or more specific host cell receptors
* controls viral tropism

viral tropism

the spectrum of cells of a host that a virus may infect

cellular tropism

viruses that recognize receptors in macrophages and neurons

tissue tropism

virus that recognize receptors in the lungs and the brain

host tropism

viruses that recognize receptors in certain hosts such as humans, rabbits, etc

gp120

* part of the attachment protein in HIV
* binds to the T-cells in the human body

CCR5 or CXCR4

* part of the receptor protein
* co-receptor used to aid in the attachment of HIV

HIV mutations

* occur in the CCR5 receptor
* renders the virus unable to attach to the target cell
* people are immune to HIV-1

bone marrow transplant

procedure that “gives” people immunity to HIV

stages in viral replication cycle

* attachment
* penetration
* uncoating
* synthesis
* assembly
* release

attachment

* the first stage in the replication cycle
* the actual binding of spike proteins on the virus to the host cell receptors
* naked and enveloped viruses go through attachment

rabies virus targets

* muscles
* neurons

human papilloma’s (HPV) targets

differentiating keratinocytes

hepatitis A/B/C’s target

liver, specifically hepatocytes

human herpes simplex 1/2 target

mucoepithelium

influenza a’s target

respiratory epithelium

rotavirus and norovirus target

intestinal epithelium

cytomegalovirus’ target

* epithelium
* monocytes
* lymphocytes

rhinovirus target

nasal epithelium

poliovirus target

intestinal epithelium

epstein-barr virus target

b cell

penetration

* also called viral entry
* can occur by breaking through the membrane, endocytosis, or membrane fusion

endocytosis

process of a cell membrane engulfing a virus

receptor-mediated endocytosis

* claritin-mediated
* caveolin-mediated

uncoating

* can occur simultaneously with penetration
* involves the capsid breaking open and the viral genomic material being released

direct penetration

virus cuts into the host membrane and injects the viral genome into the cell

synthesis

* sometimes called biosynthesis or viral replication
* the actual creation of viral genomic material and viral proteins

DNA polymerase

used during DNA replication

RNA polymerase

transcribes DNA into RNA

reverse transcriptase

transcribes RNA back into DNA