Keywords: 9-14 Flashcards Preview

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Flashcards in Keywords: 9-14 Deck (26):
1

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)

2

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

3

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

4

10 Malaria vs. Babesiosis

Malaria
- Plasmodium spp.
- Outside USA
- Mosquito vector
- Big problem globally

Babesiosis
- Babesia spp.
- Mainly in US
- Tick vector

5

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)

6

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

7

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

8

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

9

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'

10

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

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

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

13

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

14

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.

15

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

16

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

17

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

18

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

19

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

20

14 Outbreak

Suspect an outbreak when there are 2 or more cases of an illness with similar characteristics linked by time, location or contacts

21

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

22

14 Metapneumovirus

discovered by “fishing” with PCR primers in a cohort of children with undiagnosed pneumonias

common cause of respiratory infections

23

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

24

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

25

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

26

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