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Koala retroviruses: characterization and impact on the life of koalas.

Denner J, Young PR - Retrovirology (2013)

Bottom Line: Koala retroviruses (KoRV) have been isolated from wild and captive koalas in Australia as well as from koala populations held in zoos in other countries.More recently, additional subtypes of KoRV that are not endogenized have been identified based on sequence differences and host cell receptor specificity (KoRV-B and KoRV-J).A specific association with fatal lymphoma and leukemia has been recently suggested for KoRV-B.

View Article: PubMed Central - HTML - PubMed

Affiliation: Robert Koch Institute, Berlin, Germany. DennerJ@rki.de.

ABSTRACT
Koala retroviruses (KoRV) have been isolated from wild and captive koalas in Australia as well as from koala populations held in zoos in other countries. They are members of the genus Gammaretrovirus, are most closely related to gibbon ape leukemia virus (GaLV), feline leukemia virus (FeLV) and porcine endogenous retrovirus (PERV) and are likely the result of a relatively recent trans-species transmission from rodents or bats. The first KoRV to be isolated, KoRV-A, is widely distributed in the koala population in both integrated endogenous and infectious exogenous forms with evidence from museum specimens older than 150 years, indicating a relatively long engagement with the koala population. More recently, additional subtypes of KoRV that are not endogenized have been identified based on sequence differences and host cell receptor specificity (KoRV-B and KoRV-J). A specific association with fatal lymphoma and leukemia has been recently suggested for KoRV-B. In addition, it has been proposed that the high viral loads found in many animals may lead to immunomodulation resulting in a higher incidence of diseases such as chlamydiosis. Although the molecular basis of this immunomodulation is still unclear, purified KoRV particles and a peptide corresponding to a highly conserved domain in the envelope protein have been shown to modulate cytokine expression in vitro, similar to that induced by other gammaretroviruses. While much is still to be learned, KoRV induced lymphoma/leukemia and opportunistic disease arising as a consequence of immunomodulation are likely to play an important role in the stability of koala populations both in the wild and in captivity.

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Electron microscopy of KoRV grown in human cells (Holland, Laue, Robert Koch Institute, Berlin).
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Figure 1: Electron microscopy of KoRV grown in human cells (Holland, Laue, Robert Koch Institute, Berlin).

Mentions: The KoRVs have the typical morphology, size (KoRV-A, Figure 1) and genome organization (Figure 2) of the gammaretroviruses. Like all retroviruses they encode a reverse transcriptase and structural proteins including the main core protein p27Gag and the envelope proteins gp70 and p15E [20]. Most studies to date have focused on KoRV-A which has been shown to infect cells of different species (polytropic virus) in vitro including rat, human, feline and mink but not mouse cells [10,19,20,27]. It was shown to infect rats in vivo, but it remains unclear whether it is pathogenic in rats [20]. KoRV-B also infects a wide range of cells from different species including human [9]. Using pseudotyped KoRV-J, infection of human and cat cells was observed, but not of rat and mouse cells [10]. Infection in vitro does not automatically mean that these viruses can infect in vivo and give rise to a zoonosis. For example, when the host range of a closely related gammaretrovirus, PERV, was investigated, no infection was observed in humans, primates or other species when transplanting pig cells or injecting concentrated virus, despite the fact that cells of all species with the exception of mice could be infected in vitro (for review see [28]).


Koala retroviruses: characterization and impact on the life of koalas.

Denner J, Young PR - Retrovirology (2013)

Electron microscopy of KoRV grown in human cells (Holland, Laue, Robert Koch Institute, Berlin).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4016316&req=5

Figure 1: Electron microscopy of KoRV grown in human cells (Holland, Laue, Robert Koch Institute, Berlin).
Mentions: The KoRVs have the typical morphology, size (KoRV-A, Figure 1) and genome organization (Figure 2) of the gammaretroviruses. Like all retroviruses they encode a reverse transcriptase and structural proteins including the main core protein p27Gag and the envelope proteins gp70 and p15E [20]. Most studies to date have focused on KoRV-A which has been shown to infect cells of different species (polytropic virus) in vitro including rat, human, feline and mink but not mouse cells [10,19,20,27]. It was shown to infect rats in vivo, but it remains unclear whether it is pathogenic in rats [20]. KoRV-B also infects a wide range of cells from different species including human [9]. Using pseudotyped KoRV-J, infection of human and cat cells was observed, but not of rat and mouse cells [10]. Infection in vitro does not automatically mean that these viruses can infect in vivo and give rise to a zoonosis. For example, when the host range of a closely related gammaretrovirus, PERV, was investigated, no infection was observed in humans, primates or other species when transplanting pig cells or injecting concentrated virus, despite the fact that cells of all species with the exception of mice could be infected in vitro (for review see [28]).

Bottom Line: Koala retroviruses (KoRV) have been isolated from wild and captive koalas in Australia as well as from koala populations held in zoos in other countries.More recently, additional subtypes of KoRV that are not endogenized have been identified based on sequence differences and host cell receptor specificity (KoRV-B and KoRV-J).A specific association with fatal lymphoma and leukemia has been recently suggested for KoRV-B.

View Article: PubMed Central - HTML - PubMed

Affiliation: Robert Koch Institute, Berlin, Germany. DennerJ@rki.de.

ABSTRACT
Koala retroviruses (KoRV) have been isolated from wild and captive koalas in Australia as well as from koala populations held in zoos in other countries. They are members of the genus Gammaretrovirus, are most closely related to gibbon ape leukemia virus (GaLV), feline leukemia virus (FeLV) and porcine endogenous retrovirus (PERV) and are likely the result of a relatively recent trans-species transmission from rodents or bats. The first KoRV to be isolated, KoRV-A, is widely distributed in the koala population in both integrated endogenous and infectious exogenous forms with evidence from museum specimens older than 150 years, indicating a relatively long engagement with the koala population. More recently, additional subtypes of KoRV that are not endogenized have been identified based on sequence differences and host cell receptor specificity (KoRV-B and KoRV-J). A specific association with fatal lymphoma and leukemia has been recently suggested for KoRV-B. In addition, it has been proposed that the high viral loads found in many animals may lead to immunomodulation resulting in a higher incidence of diseases such as chlamydiosis. Although the molecular basis of this immunomodulation is still unclear, purified KoRV particles and a peptide corresponding to a highly conserved domain in the envelope protein have been shown to modulate cytokine expression in vitro, similar to that induced by other gammaretroviruses. While much is still to be learned, KoRV induced lymphoma/leukemia and opportunistic disease arising as a consequence of immunomodulation are likely to play an important role in the stability of koala populations both in the wild and in captivity.

Show MeSH
Related in: MedlinePlus