Viruses and Disease Flashcards
What are some features of viruses?
-Have DNA or RNA not both
-10s to 100s genes
-Protein coat (capsid)
-Obligate intracellular parasites
-No ribosomes
-Seen by elctron microscope
Simple virus life cycle
- Receptor binding
- Host replicates viral components
3.New viruses assemble - Release from host cell
How do viruses gain entry to hots cells?
By receptor binding
What kind of virus is Smallpox (dna or rna)
dsDNA - DOUBLE STRAND DNA
What kind of virus is Parvovirus?
ssDNA
What kind of virus is Rotavirus?
dsRNA
What kind of virus is coronaviruses?
+ssRNA
What kind of virus is measles?
-ssRNA
What kind of virus is HIV?
+ssRNA-RT - single stranded RNA retrovirus - uses reverse transcriptase (RT) to convert its RNA genome into DNA
What kind of virus is Hepatitis B?
dsDNA-RT
What is the difference between pos and neg ssRNA?
Pos RNA is similar to mRNA so can be immediately translated by host cell
Neg RNA is complimentary to mRNA and has to be converted to pos RNA by an RNA polymerase before translation
What are the diff groups of viruses?
- dsDNA e.g smallpox
- ssDNA e.g parvovirus
- dsRNA e.g rotaviruses
- +ssRNA e.g coronaviruses
- -ssRNA e.g measles
- +ssRNA-RT e.g HIV
- dsDNA-RT e.g Hep B
What does R0 of viruses mean?
Average Basic Reproduction Number
What is CFR of viruses?
Case Fatality Rate - bird flu v high
Note on Smallpox
-Eradicated Virus
-Originated in Africa
-Causes postules that cause lifelong scarring
-Variola major is more serious of the 2 kinds
-Variolation - used viral matter from smallpox patients - puss fom postule- and injected into healthy patient to create immunity
-DNA virus
What role did Edward Jenner play in smallpox immunisation?
Realised if created vaccine from cow pox - would prevent smallpox
Note on Herpes Virus
-Lifelong infection
-Herpes Simplex-1 (HSV-1) causes cold sores
-Resides in neuronal cells and can be activated by diff things e.g sun, stress, temp
-Primary infection and latent phase where resides in neuronal cells
What are shingles?
Reactivation of chicken pox (Varicella Zoster virus) later in life
Evolution of retroviruses
1.Receptor binding
2.Fusion with host cell surface
3.Reverse transcriptase creates viral RNA into viral DNA
4.Integration into host DNA
5.Transcription
6.Translation
7.Assembly- virus core structure
8.Budding
9.Release
What is HIV target cell and why?
Retrovirus
CD4 lymphocyte (T cell) - provides most immunity
How is HIV transmissed?
-Unprotected sex
-Blood transfusion
-Needles
-Mother to baby
What therapies are there for HIV?
-Education, clean needles, contraceptives
-Antivirals : combination anti-retroviral therapy, nucleosides, protease inhibitors, RT inhibitors, HIV triple therapy
What are zoonotic viruses and what are some examples?
Viruses that jump between species e.g influenza, HIV, ebola, SARS-CoV-2
How is SARS-CoV-2 spread and how does it persist?
Spread via droplets suspended in air from sneezing or coughing
Virus remains in airways - spike proteins stick tightly to glycans of mucins in the mucus that line the airway epithelium
What receptor does SARS-CoV-2 bind to?
Binds to ACE2 receptors on host cells and in respiratory tract
What distinguishing feature does SARS-CoV-2 have that helps it with persistence?
Has a crown like structure created by surface spike proteins
-RNA virus
How to monitor viruses by testing sewage water?
- Collect sample from wastewater treatment plant
- Centrifuge the sample and purify RNA in the lab
- Quantify RNA and determine virion numbers
