1. Pathogenic Viruses continued
Herpes Virus family
VZV, CMV, and EBV
Hepatitis viruses
Hep A, B, and C: all unrelated, and transmitted differently, but cause similar disease.
Picornaviruses
Mosquito-borne viruses of Arkansas
Influenza
HIV (guest speaker Debbie Biazo of NARAN)

2. Herpes virus family Human herpes viruses now numbered As a family:
But common names easier to use.
As a family:
ability to become latent;
predilection for either nervous tissue or lymphocytes;
ability to cause cancer.
Herpes roster:
Herpes simplex, Varicella zoster, cytomegalovirus, Epstein Barr, roseola, Kaposi’s sarcoma virus.

3. Herpes Simplex viruses
HHV1 (above the waist)
Typically oral, cold sores; flu-like symptoms, etc.
HHV2 (genital), STD and neonatal
Painful, contagious sores on genitals, overlap w/ HHV1.
Latency
Viruses enter nearby nerve cells, remain until activated by stress of some sort, cause disease, then return.
Spread and treatment:
Person to person by direct contact; spread within host by forming syncytia, escape immune system.
Acyclovir helps; no cure, lifetime infection.

4. Herpes family: Varicella Zoster
Varicella: chicken pox; Zoster: shingles
Chickenpox (not a pox virus), respiratory, disease becomes systemic with fever, malaise, skin lesions.
Very contagious; usually mild, esp. in children
Virus can become latent in nerves like Herpes simplex
Recurrence: shingles; rash, pain, on one side
Acyclovir can lessen symptoms
Beware of salicylates + viruses: Reyes syndrome
Vaccination: Varivax: attenuated vaccine

5. Herpes family: Cytomegalovirus
CMV (HHV5): Infection results in enlarged cells
Widespread asymptomatic infections, latency
Virus shed in body fluids: sex, birth, transplants
Problem for unborn, immunosuppressed, transplant patients; major cause of viral-induced birth defects.
Epstein Bar Virus
Cause of infectious mononucleosis
Infects B lymphocytes and salivary glands
With malaria, increased risk of cancer
Burkitt’s Lymphoma

6. Hepatitis Hepatitis is inflammation of the liver
Liver especially important in metabolism
Breakdown of drugs, toxins, waste products
Damage results in accumulation of bilirubin
Bilirubin is stage in hemoglobin breakdown
Results in yellow color: jaundice
Hepatitis can be caused by several different viruses
Hepatitis A, B, and C viruses all cause liver damage, but are unrelated viruses.

7. Hepatitis B A DNA virus: “Hepadnavirus”
Hepatitis B released from live cells, so accumulates in high numbers in body fluids.
Blood of infected person is rather infectious
Cuts, piercing, sex, childbirth, etc.
Large amounts of empty capsids ties up antibodies.
After exposure, long incubation, long disease
10% have chronic infections
The younger the host, the likelier chronic infection

8. Hep B continued Chronic infection correlated with liver destruction
Liver tissue replaced by scar tissue; liver failure
Long term exposure to virus increases risk of liver cancer
Insertion of HBV DNA into chromosome may activate oncogenes
Vaccination now recommended
Because of bad result of early infection and great danger of liver damage, liver cancer.
Recombinant vaccine.

9. Hepatitis A virus A small RNA virus, “Picornavirus”
Transmitted by fecal-oral route
Incubation for 1 month, followed by fever, nausea, anorexia, jaundice
T cells attack infected liver cells
No chronic infections, patients recover.
Note comparisons to Hepatitis B:
RNA vs DNA
Shorter disease, few long term problems
Mode of spread completely different

10. Hepatitis C Another RNA virus, different group: “Flavivirus”
Causes chronic infections
Can be mild, or destructive
Long term infections increase risk of cancer.
Transmission like Hep B: blood, sex, transplants
New hepatitis viruses being regularly discovered

11. Picornaviruses Small RNA viruses Two kinds:
enteric viruses, includes Hepatitis A and polio
Rhinoviruses: major cause of common cold
Rhinoviruses have many serotypes
Variants, caused by easy mutation of RNA
Immune system can’t recognize all differences, but enough similarities that colds become less severe, less frequent with age.

12. Arkansas Arboviruses
Not an official taxonomic group, but short for “arthropod-borne”
Includes Flaviviruses, Togaviruses, and others.
Zoonotic, spread from animals to people by arthropod vectors, especially mosquitoes.
Reservoirs may be birds, various mammals
Result in two main types of illnesses
Encephalitis, inflammation of the brain
Hemorrhagic fever: high fever with bleeding

13. Arkansas Arboviruses Encephalitis: spread by skeeters
In Arkansas: Eastern Equine;
Togavirus;
Also infects, kills horses. Most dangerous.
St. Louis encephalitis,
Flaviviral diseases; Human disease.
Usually not serious.
West Nile virus
Flavivirus; imported to US, spread from NYC
Disease mostly in young and elderly

14. Orthomyxovirus Influenza: a serious respiratory disease
Virus has a segmented genome
8 different RNA molecules
Spikes: Hemagglutinin (for infecting cells) and neuraminidase (for escaping them)
Antigenic drift and shift
Drift: small mutations, making host susceptible
Shift: major mixing of RNAs, whole new virus.
Attack on respiratory tract
Kills ciliated epithelial cells, allows bacterial infections. Release of interferon causes symptoms.

15. View of flu http://www.astrosurf.org/lombry/Bio/virus-influenza.jpg

16. influenza Changes in H and N (antigenic shift)
Mixing of viruses that infect birds, pigs, produce new strains able to jump to humans.
New antigenic type leaves population unprotected
Numerous epidemics throughout history
Flu of killed 20 million
Asia watched very carefully
Flu vaccines made from deactivated viruses
Slow process, so every year correct strains are “guessed”.

17. HIV/AIDS Infection 4 main types of cells infected, esp. T helper cells
Have CD4 glycoprotein on surface
After RNA is copied into cDNA, cDNA inserts
Infection is for life
Chronic infection
T cells continually made, continually destroyed
Eventually, host loses
AIDS diagnosis:
CD4 count below 200/µl; opportunistic infections

18. Treatment and prevention
Prevention is easy
Practice monogamous sex, avoid shared needles
HIV cannot be spread by casual contact, skeeters
Fastest growing victim demographic is YOU.
Not just a “gay disease”
Treatment is expensive, but usually works
Nuceloside analogs, protease inhibitors
Processing viral proteins requires protease
About $1500 a month for drugs