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Development of a model for marburgvirus based on severe-combined immunodeficiency mice.

Warfield KL, Alves DA, Bradfute SB, Reed DK, VanTongeren S, Kalina WV, Olinger GG, Bavari S - Virol. J. (2007)

Bottom Line: Here, we demonstrate that serially passaging liver homogenates from MARV-infected severe combined immunodeficient (scid) mice was highly successful in reducing the time to death in scid mice from 50-70 days to 7-10 days after MARV-Ci67, -Musoke, or -Ravn challenge.We performed serial sampling studies to characterize the pathology of these scid mouse-adapted MARV strains.These scid mouse-adapted MARV models appear to have many similar properties as the MARV models previously developed in guinea pigs and nonhuman primates.

View Article: PubMed Central - HTML - PubMed

Affiliation: United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Maryland, USA. kelly.warfield@us.army.mil

ABSTRACT
The filoviruses, Ebola (EBOV) and Marburg (MARV), cause a lethal hemorrhagic fever. Human isolates of MARV are not lethal to immmunocompetent adult mice and, to date, there are no reports of a mouse-adapted MARV model. Previously, a uniformly lethal EBOV-Zaire mouse-adapted virus was developed by performing 9 sequential passages in progressively older mice (suckling to adult). Evaluation of this model identified many similarities between infection in mice and nonhuman primates, including viral tropism for antigen-presenting cells, high viral titers in the spleen and liver, and an equivalent mean time to death. Existence of the EBOV mouse model has increased our understanding of host responses to filovirus infections and likely has accelerated the development of countermeasures, as it is one of the only hemorrhagic fever viruses that has multiple candidate vaccines and therapeutics. Here, we demonstrate that serially passaging liver homogenates from MARV-infected severe combined immunodeficient (scid) mice was highly successful in reducing the time to death in scid mice from 50-70 days to 7-10 days after MARV-Ci67, -Musoke, or -Ravn challenge. We performed serial sampling studies to characterize the pathology of these scid mouse-adapted MARV strains. These scid mouse-adapted MARV models appear to have many similar properties as the MARV models previously developed in guinea pigs and nonhuman primates. Also, as shown here, the scid-adapted MARV mouse models can be used to evaluate the efficacy of candidate antiviral therapeutic molecules, such as phosphorodiamidate morpholino oligomers or antibodies.

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Adaptation of MARV to severe combined immunodeficiency (scid) mice. Groups of scid mice (n = 10) were infected with ~1000 pfu of wild-type MARV-Ci67, -Musoke, or -Ravn. The livers of two mice from each group were harvested 7–8 days after infection, pooled together, homogenized, and blind-passaged into a new group of naïve scid mice. Blind passaging proceeded until a mean time-to-death of 7–10 days was observed consistently through several passages. (A-C) The remaining eight mice from each group were monitored for survival and the data are presented as the time-to-death for each animal (filled circles) and the mean time-to-death (line). (D-F) The viral titers in the pooled liver homogenates were determined after each passage in scid mice. P15: Passage 15, P10: Passage 10.
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Figure 1: Adaptation of MARV to severe combined immunodeficiency (scid) mice. Groups of scid mice (n = 10) were infected with ~1000 pfu of wild-type MARV-Ci67, -Musoke, or -Ravn. The livers of two mice from each group were harvested 7–8 days after infection, pooled together, homogenized, and blind-passaged into a new group of naïve scid mice. Blind passaging proceeded until a mean time-to-death of 7–10 days was observed consistently through several passages. (A-C) The remaining eight mice from each group were monitored for survival and the data are presented as the time-to-death for each animal (filled circles) and the mean time-to-death (line). (D-F) The viral titers in the pooled liver homogenates were determined after each passage in scid mice. P15: Passage 15, P10: Passage 10.

Mentions: Previously, an Ebola Zaire mouse-adapted virus was developed by performing 9 sequential passages of Ebola Zaire '76 virus in suckling mice [14]. We chose to take a slightly different approach, by repeatedly passaging MARV-Ci67, -Musoke, or -Ravn in scid mice after initial inoculation with the wild-type (i.e. human-derived) viruses. The livers of two mice were harvested on day 7–8 after each infection, pooled together, homogenized, and blind-passaged into naïve scid mice until a mean time-to-death (MTD) of ≤10 days was observed through several passages (Figure 1A–C). The starting time to death of the scid mice varied after injection with the wild-type MARV isolates. MARV-Musoke began with the highest MTD of 61.5 (± 9.67) days and dropped to 9.375 (± 1.30) days within 10 passages. For MARV-Ci67, the MTD was 51.6 (± 4.98) days for the wild-type virus and was 7.75 (± 0.46) days after 15 passages. The MTD for MARV-Ravn began at 39.4 (± 5.48) days and was 10.3 (± 0.71) days after 10 passages in scid mice. The viral titers in the liver homogenates from each passage were determined using plaque assay and we found an upward trend in the viral titers amongst the liver homogenates with increasing passage in mice (Figure 1D–F). The increase in viral titer in the day 7 liver homogenates seemed to correspond with a decrease in the MTD of the inoculated mice.


Development of a model for marburgvirus based on severe-combined immunodeficiency mice.

Warfield KL, Alves DA, Bradfute SB, Reed DK, VanTongeren S, Kalina WV, Olinger GG, Bavari S - Virol. J. (2007)

Adaptation of MARV to severe combined immunodeficiency (scid) mice. Groups of scid mice (n = 10) were infected with ~1000 pfu of wild-type MARV-Ci67, -Musoke, or -Ravn. The livers of two mice from each group were harvested 7–8 days after infection, pooled together, homogenized, and blind-passaged into a new group of naïve scid mice. Blind passaging proceeded until a mean time-to-death of 7–10 days was observed consistently through several passages. (A-C) The remaining eight mice from each group were monitored for survival and the data are presented as the time-to-death for each animal (filled circles) and the mean time-to-death (line). (D-F) The viral titers in the pooled liver homogenates were determined after each passage in scid mice. P15: Passage 15, P10: Passage 10.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2164958&req=5

Figure 1: Adaptation of MARV to severe combined immunodeficiency (scid) mice. Groups of scid mice (n = 10) were infected with ~1000 pfu of wild-type MARV-Ci67, -Musoke, or -Ravn. The livers of two mice from each group were harvested 7–8 days after infection, pooled together, homogenized, and blind-passaged into a new group of naïve scid mice. Blind passaging proceeded until a mean time-to-death of 7–10 days was observed consistently through several passages. (A-C) The remaining eight mice from each group were monitored for survival and the data are presented as the time-to-death for each animal (filled circles) and the mean time-to-death (line). (D-F) The viral titers in the pooled liver homogenates were determined after each passage in scid mice. P15: Passage 15, P10: Passage 10.
Mentions: Previously, an Ebola Zaire mouse-adapted virus was developed by performing 9 sequential passages of Ebola Zaire '76 virus in suckling mice [14]. We chose to take a slightly different approach, by repeatedly passaging MARV-Ci67, -Musoke, or -Ravn in scid mice after initial inoculation with the wild-type (i.e. human-derived) viruses. The livers of two mice were harvested on day 7–8 after each infection, pooled together, homogenized, and blind-passaged into naïve scid mice until a mean time-to-death (MTD) of ≤10 days was observed through several passages (Figure 1A–C). The starting time to death of the scid mice varied after injection with the wild-type MARV isolates. MARV-Musoke began with the highest MTD of 61.5 (± 9.67) days and dropped to 9.375 (± 1.30) days within 10 passages. For MARV-Ci67, the MTD was 51.6 (± 4.98) days for the wild-type virus and was 7.75 (± 0.46) days after 15 passages. The MTD for MARV-Ravn began at 39.4 (± 5.48) days and was 10.3 (± 0.71) days after 10 passages in scid mice. The viral titers in the liver homogenates from each passage were determined using plaque assay and we found an upward trend in the viral titers amongst the liver homogenates with increasing passage in mice (Figure 1D–F). The increase in viral titer in the day 7 liver homogenates seemed to correspond with a decrease in the MTD of the inoculated mice.

Bottom Line: Here, we demonstrate that serially passaging liver homogenates from MARV-infected severe combined immunodeficient (scid) mice was highly successful in reducing the time to death in scid mice from 50-70 days to 7-10 days after MARV-Ci67, -Musoke, or -Ravn challenge.We performed serial sampling studies to characterize the pathology of these scid mouse-adapted MARV strains.These scid mouse-adapted MARV models appear to have many similar properties as the MARV models previously developed in guinea pigs and nonhuman primates.

View Article: PubMed Central - HTML - PubMed

Affiliation: United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Maryland, USA. kelly.warfield@us.army.mil

ABSTRACT
The filoviruses, Ebola (EBOV) and Marburg (MARV), cause a lethal hemorrhagic fever. Human isolates of MARV are not lethal to immmunocompetent adult mice and, to date, there are no reports of a mouse-adapted MARV model. Previously, a uniformly lethal EBOV-Zaire mouse-adapted virus was developed by performing 9 sequential passages in progressively older mice (suckling to adult). Evaluation of this model identified many similarities between infection in mice and nonhuman primates, including viral tropism for antigen-presenting cells, high viral titers in the spleen and liver, and an equivalent mean time to death. Existence of the EBOV mouse model has increased our understanding of host responses to filovirus infections and likely has accelerated the development of countermeasures, as it is one of the only hemorrhagic fever viruses that has multiple candidate vaccines and therapeutics. Here, we demonstrate that serially passaging liver homogenates from MARV-infected severe combined immunodeficient (scid) mice was highly successful in reducing the time to death in scid mice from 50-70 days to 7-10 days after MARV-Ci67, -Musoke, or -Ravn challenge. We performed serial sampling studies to characterize the pathology of these scid mouse-adapted MARV strains. These scid mouse-adapted MARV models appear to have many similar properties as the MARV models previously developed in guinea pigs and nonhuman primates. Also, as shown here, the scid-adapted MARV mouse models can be used to evaluate the efficacy of candidate antiviral therapeutic molecules, such as phosphorodiamidate morpholino oligomers or antibodies.

Show MeSH
Related in: MedlinePlus