Keywords: 9-14 Flashcards
9 Fungi:
How obtain nutrients
Reproduction
Motility
Staining
How enhance survival
Chemotrophic: secrete enzymes that degrade organic substrates into soluble nutrients that are absorbed into the cell
Reproduce sexually
Non-motile
- Unstained w/ gram stain
- Stain w/ calcofluor
- Stained by silver stains & PAS (stain polysaccharide in viable cell walls)
Produce spores to enhance their survival (dispersed, resistant to adverse conditions, germinate when conditions fro growth are favorable)
9 Mycoses:
Classifications
Resistance
Fungal allergies
Fungal toxicoses
Superficial, cutaneous (most frequent), subcutaneous, systemic, & opportunistic (w/ underlying immunocompromise)
Phagocytosis by neutrophilic granulocytes & macrophages
Spores contain allergens –> hypersensitivity reactions (allergic rhinitis, bronchial asthma, allergic alveolitis)
Mycotoxins: ingested w/ food on which fungi grow
- Aflatoxins: produced by Aspergillus, cause primary hepatocellular carcinoma
10 Protozoa that cause diarrhea (4)
Entamoeba histolytica
- Bloody diarrhea, liver abscess
- Worldwide, rare in USA
Giardia lamblia
- Frothy, smelly diarrhea, abdominal bloating
- Worldwide, including USA
- Persons w/ IgA deficiency at higher risk
Crytposporidium
- Prolonged diarrhea
- Worldwide, including USA
Microsporidium
- Immunocompromised patients (AIDS)
- Worldwide, including USA
10 Malaria vs. Babesiosis
Malaria
- Plasmodium spp.
- Outside USA
- Mosquito vector
- Big problem globally
Babesiosis
- Babesia spp.
- Mainly in US
- Tick vector
10 Common Ectoparasites Infesting Humans
Lice
- Scalp hair (pediculosis capitis, nits)
- Body hair (pediculosis corporis, body lice)
- Pubic hair (crabs)
Scabies
- Caused by Sarcoptes scabei
- Produces itchy skin & an allergic reaction w/ a scaly rash
Myiasis
- Infestation of subcutaneous tissue by fly larvae (maggots)
11 Properties of Viruses:
Type of pathogens
Genomes surrounded by…
New intact infectious virus particles
Attachment
Entry
Infection controlled by…
Immune evasion
Diagnosis
Treatments
Obligate intracellular parasites
Capsid (some surrounded by an envelope)
Virions
Attach by binding to receptors on host cell surface
Enter host cells by endocytosis or direct penetration
Cell-mediated immunity
Latent or persistent viral infections, high replication & mutation rates, drug resistance
Cell culture, immunocytochemical staining, PCR
Few
11 Virus Structure & Definitions:
Virion
Viral Genome
Capsid
Capsomere
Nucleocapsid
Symmetry
Neutralizing antibodies
Intact, infectious viral particle
Nucleic acid (DNA or RNA)
Protein shell surrounding nucleic acid
Clustering of capsid proteins discernible by electron microscopy that may or may not compose capsids
Genome + capsid
- Helical/rod shaped capsids (enveloped viruses)
- Spherical capsid w/ icosahedral symmetry
Recognize & bind to proteins on viral surface & interfere w/ ability of virus to enter a cell
11 Central Dogma for Virus Infected Cells:
DNA to DNA
RNA to RNA
RNA o DNA
DNA to RNA
RNA to Protein
DNA dependent DNA polymerase (DNA viruses & cells)
RNA dependent RNA polymerase (RNA viruses)
RNA dependent DNA polymerase (retroviruses)
DNA dependent RNA polymerase (cells)
Translation
11 (+) vs. (-) Strands:
mRNA
DNA of equivalent polarity
RNA & DNA complement
(-) strand
(+) vs. (-) polarity
(+) strand, immediately translatable
(+) strand, would be translated into protein if it were RNA
(-) strand
Can’t be translated, must first be coped to (+) strand
(+): 5’ –> 3’
(-): 3’ –> 5’
11 Common requirements for RNA virus replication
Must make copies of themselves for assembly into virions & mRNA for the synthesis of viral proteins
Require viral polymerase
Encode an RNA-dependent RNA polymerase to catalyze the synthesis of new genomes & mRNA (except retroviruses)
11 Does the virus have to bring a viral polymerase into the cell to be infectious?
DNA viruses
(+) sense RNA
(-) sense RNA
Retroviruses
Hepatitis B virus
No
No
Yes
Yes
No
12 Viral Routes of Acquisition (5)
Alimentary tract (fecal-oral spread)
- Localized
- Systemic (enteroviruses)
Respiratory tract
- Upper localized (rhinovirus, influenza)
- Lower localized (adenovirus, influenza)
- Systemic (mumps, measles, hantavirus)
Urogenital tract (sexual contact)
- Localized (HPV)
- Systemic (HIV, HSV)
Eyes
- Systemic (enterovirus, HSV)
Parenteral inoculation (directly into bloodstream) - HIV, hepatitis B virus
Insect vector or animal bite
- Rabies
12 Diagnosis of Viral Infections (4)
Tissue culture
- Growth, detection of viral cytopathic effect (CPE)
Detection of virus particles or virion components
- Microscopic exam, immunofluorescence, electron microscopy, hemagglutination assay, ELISA, staining
Direct detection of viral genome
- PCR
Detection of antibodies made against viruses that circulate in serum
- ELISA, virus neutralization, serology
12 Serology
IgM – early, or acute infection
IgG – prior infection
A rise in virus-specific IgG between the acute phase (symptomatic phase) and the convalescent phase (2 to 4 weeks later) is diagnostic of a recent viral infection.
The window period is the period of time before circulating antibodies appear.
12 Poliovirus:
Biological Characteristics
Life Cycle
Reservoir
Transmission
Virulence Factors
Diagnosis
Treatment/Prevention
- Enterovirus genus of Picornavirus family
- Small, unenveloped, +RNA
Attachment, Entry (endocytosis w/ conformational changes), Uncoating, Replication in cytoplasm, Assembly, Egress
Humans
Oral-fecal route
- Spread through CNS
- Nonenveloped to survive acid environment of GI tract
- 2A protein: inhibits protein translation
- 2BC/3A protein: inhibits cell vesicle transport
- 3C protease: inhibits transcription
Culture stool samples or CSF
Polio vaccine
- Salk: inactivated IPV
- Sabin: oral attenuated OPV
Pleconaril
