acellular microbes 2 Flashcards
lesions of upper body
Herpes simplex virus 1 (HSV-1)
lesions of lower body
Herpes simplex virus 2
prevent organs from working properly
Human cytomegalovirus
caused by HHV-8
Kaposi’s sarcoma
kissing disease
Epstein-Barr virus
chickenpox
Varicella zoster virus
“sixth disease” occurs in infants/children induces seizures
Human herpesvirus 6 (HHV-6)
“sixth disease” mild and self-limited infection in children
Human herpesvirus 7 (HHV-7)
enveloped DNA viruses:
Hepadnaviridae
Herpesviridae
Poxviridae
viruses are pieces of host cell RNA/DNA
that have escaped from living cells
ESCAPED GENE THEORY
Three major theories to explain origin
of viruses:
COEVOLUTION THEORY
RETROGRADE EVOLUTION THEORY
ESCAPED GENE THEORY
viruses evolved from free-living prokaryotes
RETROGRADE EVOLUTION THEORY
viruses originated in the primordial soup
COEVOLUTION THEORY
Three categories based on shape:
Icosahedron bacteriophages
Filamentous bacteriophages
Complex bacteriophages
– the viruses that infects bacteria
– obligate intracellular pathogens (cannot reproduce outside cell host
BACTERIOPHAGES
almost spherical shape with 20 triangular facets
Icosahedron bacteriophages
long tubes formed by capsid proteins assembled into helical structure. Up to 900nm long
Filamentous bacteriophages
icosahedral heads attached to helical tails.
Complex bacteriophages
simple replication cycle that ends with the destruction(lysis)
LYTIC CYCLE
causes lytic cycle
VIRULENT BACTERIOPHAGES
do not immediately initiate lytic cycle
TEMPERATE PHAGES
Steps in Multiplication of Bacteriophages(Lytic Cycle):
ATTACHMENT (Adsorption)
PENETRATION
BIOSYNTHESIS
ASSEMBLY
RELEASE
the phage attaches to a protein
ATTACHMENT (Adsorption)
the phage injects its DNA into the bacterial cell
PENETRATION
phage genes are expressed
BIOSYNTHESIS
the phage pieces or parts are assembled
ASSEMBLY
– viruses that infects human and animal
– like bacteriophages, can only attach to and invade cells bearing appropriate surface receptors
ANIMAL VIRUSES
the complete phages escape
RELEASE
Steps in Multiplication of Animal Viruses:
ATTACHMENT (Adsorption)
PENETRATION
UNCOATING
BIOSYNTHESIS
ASSEMBLY
RELEASE
the virus is able to downregulate its gene expression
LATENT VIRUS INFECTIONS
functions by inhibiting certain metabolic activities
Antibiotics
viruses that causes cancer
ONCOVIRUSES
herpes virus that causes infectious mononucleosis
EPSTEIN-BARR VIRUS
causes Kaposi sarcoma,
HUMAN HERPES VIRUS 8
– the cause of AIDS, an enveloped, single stranded RNA virus
– member of a genus lentiviruses, in a family of viruses called retroviridae
– able to attach to and invade cells bearing receptors that the virus recognizes
– destroys important cells of the immune system
Human Immunodeficiency Virus (HIV)
consists of short, naked fragments of single-stranded RNA that can interfere with the metabolism of plant cells and stunt the growth of plants (sometimes killing it)
VIROIDS
– an extremely large double-stranded DNA virus recovered from amoebas
– given the name because it “mimics” bacteria
– it is so large that it can be observed using standard compound light microscope
– contains several genes for sugar, lipid, and amino acid metabolism
MIMIVIRUS
– even larger double-stranded DNA virus discovered in water sample off the coast
of Chile(2010)
– given the name Megavirus chilensis
– has the largest capsid diameter (440nm) and the largest and most complex genome of all known viruses
– isolated in a French laboratory by co cultivation with amoebas
– natural host not known
MEGAVIRUS
examples of prions:
scrapie
mad cow disease
kuru – loss of coordination and dimentia
GSS disease – loss of coordination and dementia
small infectious proteins that apparently causes fatal neurological diseases
PRIONS
