(V) 28: Koala Retroviruses

Question 1

Zoonotic diseases

Answer 1

aka zoonoses

caused by infections that spread btwn animals and people

Question 2

Ebola

Answer 2

a ZOONOTIC disease

Ebola reservoir (actual host) = BATS
- viral infection is not serious in natural reservoir

Question 3

Ebola transmission

Answer 3

Animal-to-animal transmission
- bats are reservoir hosts and can transmit to other animals (apes, monkeys, antelopes) and humans

Spillover event
- when animal (bat, ape, monkey, antelope) or human becomes infected w/ Ebola through contact w/ reservoir host
- could be through hunting or preparing animal’s meat for eating

Question 4

KoRV

Answer 4

Koala Retrovirus (host: koala)

Question 5

Koala Population Decline

Answer 5

• populations declining by 50-60% in mainland Australia (partly due to global warming)
• there is evidence of lymphomas and leukemia in koalas (often malignant)

Question 6

Discovery of Koala Retrovirus

Answer 6

• ENDOGENOUS retrovirus
• transmission through GERM CELLS
• similar to exogenous gammaretrovirus gibbon ape leukemia virus (GALV)

koalas were likely infected by GALV for origin of KoRV

Question 7

Endogenization of Koala Retrovirus

Answer 7

• events for KoRV infections are believed to be decades ago
• resulted in COLONIZATION of koala genome germline by KoRV
• original virus, KoRV-A, was discovered in Australia (endogenous retrovirus that started colonizing koalas)

Question 8

KoRV-A

Answer 8

• no direct establishment of lymphomas, leukemias and immunodeficiencies to KoRV-A
• further research to discover potential causes

Question 9

Infection status of Koalas in US Zoos

Answer 9

San Diego Zoo vs Los Angeles Zoo

San Diego Zoo: very LIMITED outbreeding, very LOW neoplastic disease (leukemias + lymphomas)

LA Zoo: inclusion of Australian koalas for breeding, HIGHER rates of neoplastic disease

• KoRV-A found in San Diego Koalas
• ALL LA Zoos had KoRV-A
• some LA Zoo Koalas had KoRV-B (a new isolate)

Question 10

KoRV-B

Answer 10

KoRV-B is linked to animals having a HIGHER degree of neoplasia = MORE DISEASE

• comes in EXOGENOUSLY but effect and neoplasia is only present b/c of colonization of genome w/ KoRV-A

Question 11

Endogenous RV

Answer 11

Endogenous RV usually does NOT cause disease

When endogenous RV is in presence of exogenous RV = increased disease

Question 12

KoRV-B vs KoRV-A

Answer 12

• differences in genome
• differences in receptor usage

Question 13

HERVs

Answer 13

8-10% of our genome is made of endogenous retroviruses

suggested links btwn HERVs and systemic lupus erythematosus, an autoimmune disease