Microbiology Refresher - Viruses and Fungi Flashcards
What are the single most important cause of infectious disease morbidity and mortality worldwide?
viruses
What is going to expose us to new and emerging pathogens/viruses?
continued destruction of natural habitats and interactions with wildlife
What describes what happened around 1908, where an event occurred which was possibly the first contact between humans and HIV virus?
The “cut hunter” hypothesis
What is the hypothesis that describes a chimp and human hunter had a bloody encounter and the human acquired SIV (simian immunodeficiency virus) which later mutated to HIV?
the “cut hunter” hypothesis
Most research of viruses in humans is centered on viruses of what?
the respiratory tract
Constant exposure to a variety of viruses does what?
primes our immune system (may be beneficial or detrimental)
What has been linked to systemic inflammatory diseases?
viruses
What causes inflammation and multi-organ disease?
HIV
What is linked to MS?
epstein-barr virus
Viral infections prime the T-helper cell 1 system which acts as what?
protective immunity (more exposure=more immunity)
What is linked to allergic diseases including asthma?
Th2
Viruses alter the respiratory epithelium and promote (1)?
- secondary bacterial infections (influenza and epstein-barr)
What are some common pathogenic viruses in humans?
- respiratory viruses
- gastrointestinal tract viruses
- skin viruses
- other viruses (Zika)
Viruses may have what that is not encoded by the genome of the virus?
a lipid envelope
What can viruses do to the lipid envelope from the host as it buds off the host cell?
they can steal the lipid envelope
What uses its own DNA or RNA to encode the protein spikes on the lipid envelope?
viruses
What can changes in spike proteins on viruses lead to?
resistance in treatment
What are the different types of viral capsids?
- enveloped
- helical
- polyhedral
- icosahedral
What types of viruses dry out easier and are usually transmitted by respiratory, parenteral (blood), and sexual routes?
viruses with lipid envelopes
What types of viruses are more stable and usually transmitted in the fecal-oral route?
viruses without lipid envelopes
How are viruses classified?
- type and structure of viral nucleic acid used for replication (DNA vs. RNA)
- symmetry of viral capsid
- presence or absence of a lipid envelope of the virus
Where are the different locations of viral replication?
- DNA viruses - in nucleus
- RNA - in cytoplasm of host
What uses reverse transcriptase to reverse transcribe the RNA in their own genome into DNA, which is then incorporated into host cells?
retroviruses (HIV)
What are the steps that occur when the virus meets the host?
- attaches to host cells
- receptors on virus attach itself to specific viral receptors of the host cell
- virus enters host cell by fusion or endocytosis
- viral capsule disassembles
Once the virus has entered the host cell, it uses some of its own proteins and host ribosomes to (1), creating many (2)
- reproduce
- viral progeny
Release of viral progeny occurs by what ways?
- budding from cell membrane
- secretion
- cell lysis
What can induce apoptosis in host cells?
RNA and DNA viruses
What results in damage to host cell structure and sometimes death of infected host cells?
apoptosis
What is the mechanism of infection for influenza?
- upon meeting respiratory epithelium, hemagglutinin on envelope of virus attaches to sialic acid receptor on epithelial cell surface
- viral structure is internalized into cell in an endosome
- further changes allow genetic material of virus to uncoat, leave the virus, and enter the cytoplasm, making its way to the nucleus
- within nucleus, viral RNA replication occurs, formed viral progeny and releasing to cell surface
- neuraminidase allows virus to “escape” cell and “not stick” to surface of host cell
What allows influenza virus to escape cell and not stick to surface of host cell?
neuraminidase
What are direct methods of virus transmission?
- person-to-person
- droplet
What are indirect methods of virus transmission?
- fecal-oral
- airborne
- fomite (surface)
What are vector methods of virus transmission?
- insect bite
What type of viruses produce characteristic upper respiratory symptoms?
common cold viruses
What type of virus has a recognizable rash?
chicken pox (varicella virus)
What type of virus causes anosmia (inability to smell) and characteristic changes on lung imaging?
COVID-19 (delta variant)
What may help in diagnosing viruses?
non-specific testing such as CBC panels
What is often normal in viral infections?
WBC