Safety and feasibility of apheresis to harvest and concentrate parasites from subjects with induced blood stage Plasmodium vivax infection
Background In the absence of a method to culture Plasmodium vivax , the only way to source parasites is ex vivo . This hampers many aspects of P. vivax research. We assessed the safety of apheresis, a method for selective removal of specific components of blood as a means of extracting and concentrating P. vivax parasites.
Methods An iterative approach was employed across four non-immune healthy human subjects in separate cohorts. All four subjects were inoculated with ~564 blood stage P. vivax parasites (HMP013- Pv ) and subjected to apheresis 10 to 11 days later. Blood samples collected during apheresis were tested for the presence and concentration of P. vivax parasites by microscopy, flow cytometry, 18S rDNA qPCR for total parasites, and pvs2 5 qRT-PCR for female gametocyte transcripts. Safety was determined by monitoring adverse events. Malaria transmission to mosquitoes was assessed by membrane feeding assays.
Results There were no serious adverse events and no significant safety concerns. Apheresis concentrated asexual parasites by up to 4.9-fold (range: 0.9 - 4.9-fold) and gametocytes by up to 1.45-fold (range: 0.38 - 1.45-fold) compared to pre-apheresis densities. No single haematocrit layer contained >40% of all the recovered P. vivax asexual parasites. Ex vivo concentration of parasites by percoll gradient centrifugation of whole blood achieved greater concentration of gametocytes than apheresis. Mosquito transmission was enhanced by up to 5-fold in a single apheresis sample compared to pre-apheresis.
Conclusion The modest level of parasite concentration suggests that the use of apheresis may not be an ideal method for harvesting P. vivax parasites.
Trial Registration Australia New Zealand Clinical Trials Registry (ANZCTR) Trial ID: ACTRN12617001502325 registered on 19th October 2017. https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=373812
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Safety and feasibility of apheresis to harvest and concentrate parasites from subjects with induced blood stage Plasmodium vivax infection
On 14 Jan, 2021
On 03 Jan, 2021
On 02 Jan, 2021
On 02 Jan, 2021
On 02 Jan, 2021
Posted 29 Dec, 2020
On 29 Dec, 2020
On 29 Dec, 2020
On 29 Dec, 2020
On 29 Dec, 2020
Posted 26 Dec, 2020
On 26 Dec, 2020
On 23 Dec, 2020
On 23 Dec, 2020
On 23 Dec, 2020
Posted 03 Apr, 2020
Received 30 Apr, 2020
On 09 Apr, 2020
Invitations sent on 08 Apr, 2020
On 03 Apr, 2020
On 02 Apr, 2020
On 01 Apr, 2020
On 31 Mar, 2020
Background In the absence of a method to culture Plasmodium vivax , the only way to source parasites is ex vivo . This hampers many aspects of P. vivax research. We assessed the safety of apheresis, a method for selective removal of specific components of blood as a means of extracting and concentrating P. vivax parasites.
Methods An iterative approach was employed across four non-immune healthy human subjects in separate cohorts. All four subjects were inoculated with ~564 blood stage P. vivax parasites (HMP013- Pv ) and subjected to apheresis 10 to 11 days later. Blood samples collected during apheresis were tested for the presence and concentration of P. vivax parasites by microscopy, flow cytometry, 18S rDNA qPCR for total parasites, and pvs2 5 qRT-PCR for female gametocyte transcripts. Safety was determined by monitoring adverse events. Malaria transmission to mosquitoes was assessed by membrane feeding assays.
Results There were no serious adverse events and no significant safety concerns. Apheresis concentrated asexual parasites by up to 4.9-fold (range: 0.9 - 4.9-fold) and gametocytes by up to 1.45-fold (range: 0.38 - 1.45-fold) compared to pre-apheresis densities. No single haematocrit layer contained >40% of all the recovered P. vivax asexual parasites. Ex vivo concentration of parasites by percoll gradient centrifugation of whole blood achieved greater concentration of gametocytes than apheresis. Mosquito transmission was enhanced by up to 5-fold in a single apheresis sample compared to pre-apheresis.
Conclusion The modest level of parasite concentration suggests that the use of apheresis may not be an ideal method for harvesting P. vivax parasites.
Trial Registration Australia New Zealand Clinical Trials Registry (ANZCTR) Trial ID: ACTRN12617001502325 registered on 19th October 2017. https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=373812
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