MICROIMM Lecture 8: Koala Retroviruses

Differentiate between exogenous and endogenous retroviruses

Exogenous: Gained through needles, blood, partnerEndogenous: Through germline

Define zoonoses

Zoonotic diseases: caused by infections that spread between animals and people

Define reservoir

Natural host for the virus: the virus is around and causes infection, but doesn't really make host sick

What is the reservoir for Ebola?

Bats

Who did bats transmit Ebola to (intermediates)?

Apes, gorillas, antelopes

How did humans contract Ebola?

Hunting + consumption of animal meats

Why did humans become much more sick than infected animals?

Because humans are not accustomed to Ebola, even though the disease has existed for years in other species, our immune systems overreact --> causes deadly diseases

How is Ebola transmitted human-to-human?

- Traditional funeral practice

- Unprotected healthcare worker

- Unprotected contact with blood and bodily fluids

A virus hands around in animal host with the ultimate goal of...

one day spilling over to humans

Define endogenous retroviruses

Bits and pieces of infectious viruses that have inserted themselves into our genome; happened millions of years ago

What is the KoRV? Why is it interesting?

Koala Retrovirus, host: koala

Interesting: Emerged in last 3-4 decades, so we can methodically follow and study how this endogenous retrovirus happened

Populations of koalas declining by as much as ___% of total population in mainlaind Australia, starting in year ____

50-60%, 2007

Name some factors why koalas are declining

- Climate change (loss of habitat)

- Prone to multiple infections; death

- Viral factors

What specific disease are koalas prone to?

Chlamydia

As early as ~1960s, there was evidence of _____ and ____ in the koala population (often malignant)

lymphomas, leukemias

If something is an endogenous RV now, something had to start with ____

exogenous RV

What is GALV?

gammaretrovirus gibbon ape leukemia virus

Why is GALV significant?

Sequences (bits and pieces) in koalas is very similar to GALV; implies at some point, GALV made its way into koalas and endogenized --> able to transmit through germline

What was the original KoRV virus name?

KoRV-A (australia)

Question: is it possible KoRV-A is the cause of the lymphomas and leukemias in the young koalas? Where did this meeting occur?

No direct establishment of lymphomas, leukemias, and immunodeficiencies. Colorado

What two koala populations were compared to determine the cause?

Koalas in SD zoo, LA zoo (isolated populations)

How did the koalas in the SD zoo breed?

Very limited outbreeding (happened within the zoo), very low neoplastic disease

Define neoplastic disease

abnormal growth of new tissues (ie. lymph, leuk)

How did the koalas in the LA zoo breed?

Inclusion of Australian Koalas for breeding --> higher rates of neoplastic disease

Which of the two zoos had KoRV-A?

Both zoos

Which of the two zoos had KoRV-B?

LA zoo

What is KoRV-B?

Likely contributor to lymphomas, transmitted through breeding (sexual event)

Is KoRV-B endogenous or exogenous?

Exogenous (transmitted through breeding)

____ is conclusively resulting in lymphomas and disease

outbreeding from Australian koalas

The presence of this KoRV-B virus is linked to animals exhibiting a higher degree of ____

neoplasia and disease

Differentiate between KoRV-A and B

- Different genomes

- Different receptor usage

What is the significance about the appearance of KoRV-B?

Evidence that endogenous retroviruses are doing something; but there's always a new virus

What percent of our genome is composed of HERVs?

8-10%

Why are we not infected by this 8-10% of HERVs?

Just bits and pieces; no sequence is ever long enough to reconstruct these viruses

Do the sequences still have potential effects?

How the HERVs inserted themselves in the genome, seems to directly link to autoimmune diseases like lupus; position of HERV in genome --> means individual may be more prone

What is the full name for lupus?

systemic lupus erythematosus

Which scientist discovered the linkage between presence of HERVs and autoimmune lupus?

Maria Tokuyama (UBC)

In Ebola free patients, is there still viral RNA?

Yes, still present in semen. Proves that we know things, but we don't know a lot of things