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
12 HIV:
Biological Characteristics
Genome
Life Cycle
Latency vs. Persistence (Chronic)
- Lentivirus subfamily of Retroviruses
- Wedge-shaped dense nucleopasid core
- RT & integrase gene found in nucleocapsid
- All except REV in capsid in varying amounts
- Linear ssRNA
- Homodimer or heterodimer for genetic diversity
- Attachment: CD4, CXCR4 for lymphocytes, CCR5 for macrophages
- Entry: conformational change in TM
- Virion-associated RT: converts linear ssRNA into circular dsDNA
- dsDNA transits to nucleus w/ integrase to integrate into host DNA
- Transcription by RNAPII
- Processing of transcripts: regulated by REV
- Synthesis & processing of virion proteins
- Assembly & egress in cytoplasm or at cell surface
Cell type specific, macrophages vs DCs vs resting T-cells
12 Definitions:
Viremia
Acute infection
Persistent infection
Latent infection
Viral tropism
Disseminated infection
The presence of infectious virus in the bloodstream
Rapid, self-limiting infection
Long-term infection
Form of persistent infection in which virus is quiescent
What cells or tissues that the virus can infect
Spread of an infectious organism beyond the site of primary infection
13 Drugs:
HSV
CMV
VZV
RSV
HBV
HCV
Influenza A
Influenza B
Lassavirus
HSV: (val)acyclovir, foscarnet
CMV: (val)acyclovir, foscarnet
VZV: (val)acyclovir
RSV: ribavirin
HBV: tenofovir, emtricitabine, lamivudine, adefovir
HCV: interferon-α, ribavirin, telaprevir, boceprevir, sofosbuvir, simeprevir
IA: amantadine, rimantadine, oseltamivir, zanamivir
IB: oseltamivir, zanamivir
Lassavirus: ribavirin
13 Vaccines:
Live-Attenuated
Inactivated
Passive (Immunoglobulin)
Measles Mumps Rubella Influenza (Flumist) Varicella, Varicella Zoster Polio (OPV) Yellow Fever Smallpox Rotavirus
Hepatitis A Hepatitis B Influenza Japanese encephalitis HPV Polio (IPV) Rabies
Hepatitis A Hepatitis B VZV (chickenpox) Rabies Cytomegalovirus Respiratory Syncytial Virus
14 Outbreak
Suspect an outbreak when there are 2 or more cases of an illness with similar characteristics linked by time, location or contacts
14 Severe Acute Respiratory Syndrome (SARS):
Reservoir
Transmission
Healthy animals (civet cats, fruit bats) that can carry coronaviruses CoV) that are homologous to SARS
Early transmission from animals to humans was inefficient, but then CoV adapted to human-human transmission through mutations
14 Metapneumovirus
discovered by “fishing” with PCR primers in a cohort of children with undiagnosed pneumonias
common cause of respiratory infections
14 Different causes of meningitis, encephalitis, encephalopathy in the USA:
Bacterial (3)
Viral (4)
Fungus (1)
Prion (2)
Streptococcus pneumoniae
Neisseria meningitidis
Listeria
Enterovirus
West Nile virus
Herpes Simplex virus
Arboviruses
Cryptococcus
CJD
vCJD
14 Spongiform Encephalopathies:
Transmissable and genetic spongiform encephalopathies in humans (5)
Spongiform encephalopathies in animals (3)
- Sporadic Creutzfeldt-Jakob disease (sCJD)
- New variant Creutzfeldt-Jakob disease (vCJD)
- Kuru (Fore tribe members in New Guinea eating human brains)
- Gerstmann-Straussler-Scheinker disease (GSS)
- Fatal familial insomnia (FFI)
- Scrapie (sheep)
- Bovine spongiform encephalopathy (BSE)
- Chronic wasting disease (CWD) in elk and deer
14 Different causes of acute gastroenteritis:
Bacterial (6)
Viral (2)
Parasites (2)
Toxins (5)
E. coli Salmonella Campylobacter Yersinia Vibrio cholera Bacteroides fragilis
Norovirus
Rotavirus
Giardia
Cryptosporidium
Staphylococcal toxin Bacillus cereus Botulism Ciguatara Scombroid
14 Re-Emerging Infections:
Tuberculosis
Polio
Chikungunya
Dengue
Measles & Pertussis
Salmonellosis
Previously thought to be eradicated, now resurging due to immigration & immunocompromised pts
Re-emergence in Africa & Asia
Dengue-like illness in India & Mauritius transmitted by mosquitoes
Re-emergence in Florida, tropical viral infection
Re-emergence due to non-compliance w/ immunization
Re-emergence w/ wider food supply distribution & more antibiotic resistance
