UW MICROM 445 - Micro445-2018-02 Notes (46 pages)

Previewing pages 1, 2, 3, 22, 23, 24, 44, 45, 46 of 46 page document View the full content.
View Full Document

Micro445-2018-02 Notes



Previewing pages 1, 2, 3, 22, 23, 24, 44, 45, 46 of actual document.

View the full content.
View Full Document
View Full Document

Micro445-2018-02 Notes

32 views


Pages:
46
School:
University of Washington, Seattle
Course:
Microm 445 - Medical Virology
Medical Virology Documents
Unformatted text preview:

Microbiology 445 Medical Virology Viral Replication Spread Pathogenesis Jason Smith Ph D jgsmith2 uw edu Review Session for Exam 1 Friday April 6 4 30 5 30 PM HSB T625 Email one of us if you would like to meet individually at other times Virus Replication and Spread Spread within populations and transmission between hosts Entry into and spread within host Replication within host cells Virus Transmission Anthroponoses humans are the only host Zoonoses disease acquired from animals Direct Transmission Indirect Transmission Human Human Vector Vector Human Human Animal Animal Vector Vector Animal Human Animal Human Direct Transmission Horizontal Saliva Mucus Influenza Fecal matter Poliovirus Blood HIV Semen Genital Secretions HIV Zika Urine Hantavirus Mucosal surfaces Herpes Simplex Skin HPV Fomites inanimate objects that can spread virus by touch door knobs etc Direct Transmission Vertical Virus must cross placenta to infect fetus Virus in birth canal or in blood Virus present in milk Transmission Zoonoses Humans can be infected with certain viruses from animals Human viruses are most likely the result of a past zoonosis and adaptation of the virus to human as the only host Many of the most severe viral diseases rabies Ebola etc are zoonotic Transmission from animals to humans can be direct or indirect Zoonotic diseases are much more difficult to eradicate Indirect Transmission Vectors Vectors are living organisms that can transmit infectious diseases between humans or from animals to humans Mosquitoes are common vectors since they take blood from the host Culex Aedes aegypti Aedes albopictus Ticks can also be vectors for viruses Other bloodsucking animals can be vectors for bacteria and parasites Transmission Amplifying Host In some cases there is an intermediate amplifying host between the natural reservoir and humans Venezuelan equine encephalitis virus Humans can be a dead end host if they do not subsequently transmit the virus either directly or indirectly Go et al 2014 Transmission R0 R0 R naught is the basic reproduction number The number of people each infected person will infect in a completely susceptible population A product of Transmissibility likelihood of infection if there is contact Average rate of contact between susceptible and infected Duration of infectiousness R0 1 values mean spread through a population R0 1 values mean the virus will die out Disease R0 Measles 12 18 Smallpox 5 7 HIV 2 5 Mumps 2 5 Ebola 2014 outbreak 1 5 2 5 Transmission Virus Properties Enveloped viruses Non enveloped viruses Generally more fragile Do not live very long outside of a host cell Inactivated by heat drying detergents pH Generally more stable For which do you think fomite spread is more common Which one is more likely to survive the gastrointestinal tract Virus Replication and Spread Spread within populations and transmission between hosts Entry into and spread within host Replication within host cells Portals of Entry 1 Eyes 2 Mouth Respiratory tract Alimentary canal 3 Skin 4 Urogenital tract 5 Anus These are also routes of viral shedding but some viruses enter through one route and are shed by another Portals of Entry Skin Mammalian skin is a highly effective barrier against viruses The outer layer epidermis consists of dead cells why does this limit virus infection Viruses that use this route generally require exposure of subcutaneous surfaces or abrasions Herpes simplex infects in the lip area or herpes gladitorium in abrasions Papilloma virus at joints like knuckles warts Viruses also bypass the skin via bites usually arthropods needles tattoos surgery other trauma Portals of Entry Mucous Membranes Eye Adenovirus conjuctivitis Nose and mouth Herpes simplex HSV Genital tract Sexually transmitted viruses HSV HIV HPV Respiratory tract Most common route Alimentary canal fecal oral transmission Why are mucosal layers a preferred site Single layer epithelium with no dead layer Viruses live longer in damp environments Spread Primary Infection Virus infects initial susceptible cell Must overcome host defenses immunity and environment Dictated by tropism the capacity of a virus to infect specific cells tissues or species Localized spread of virus occurs by cell to cell spread or limited diffusion Some virus infections remain localized to site of entry common cold viruses HPV Spread Systemic After amplification at the primary site of infection some viruses spread within the body Route 1 Bloodstream and lymphatics Viremia virus in the blood Via infection of lymphocytes cell associated Cell free in blood or lymph Route 2 Nervous system Virus can infect the brain from the blood by crossing the blood brain barrier Infect peripheral nerves and travel within nerves and sometimes to the central nervous system CNS Spread Poliovirus Example Initial infection of cells and localized spread Intestinal epithelial cells for poliovirus Spreads to lymph node and multiplies Primary viremia Fever malaise non specific symptoms Infection of secondary sites Brown fat and muscle for polio More amplification Secondary viremia Infection of other organs CNS for poliovirus Secretion Viruses that cause rashes follow a similar paradigm Spread Rabies Virus Example Where does disease occur Primary site of infection common cold viruses norovirus rotavirus Herpes simplex Papillomavirus Adenovirus herpesviruses Secondary site of spread Lungs Intestines Mucous membranes Skin Eye Liver Brain and CNS Blood Hepatitis viruses Rabies herpes simplex HIV Disseminated disease Skin rash Small pox measles Virus Replication and Spread Spread within populations and transmission between hosts Entry into and spread within host Replication within host cells Steps of Viral Replication 1 Attachment 2 Penetration 3 Uncoating of nucleic acid 4 Viral protein expression 4a Early viral protein synthesis 5 Replication of viral genome 4b Late viral protein synthesis structural proteins 6 Assembly 7 Release 8 Maturation can occur before release Replication of Naked Viruses Attachment Penetration Assembly Maturation Replication Uncoating mRNA mRNA Polymerase Early protein expression Non structural proteins Cell lysis Late gene expression Structural proteins Replication of Enveloped Viruses Attachment Release Penetration Replication Uncoating mRNA Assembly Maturation mRNA Polymerase Early protein expression Non structural proteins Late gene expression Structural proteins Attachment Virus attachment protein VAP binds to a receptor on the surface


View Full Document

Access the best Study Guides, Lecture Notes and Practice Exams

Loading Unlocking...
Login

Join to view Micro445-2018-02 Notes and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Micro445-2018-02 Notes and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?