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Please use this identifier to cite or link to this item: https://hdl.handle.net/2445/141198
Differential expression of var subgroups and PfSir2a genes in afebrile Plasmodium falciparum malaria: a matched case-control study
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Background: Poor knowledge on the afebrile Plasmodium falciparum biology limits elimination approaches to target
asymptomatic malaria. Therefore, the association of parasite factors involved in cytoadhesion, parasite multiplication
and gametocyte maturation with afebrile malaria was assessed.
Methods: Plasmodium falciparum isolates were collected from febrile (axillary temperature≥37.5 °C or a reported
fever in the previous 24 h) and afebrile (fever neither at the visit nor in the previous 24 h) individuals residing in Southern Mozambique. var, PfSir2a and Pfs25 transcript levels were determined by reverse transcriptase quantitative PCRs
(RT-qPCRs) and compared among 61 pairs of isolates matched by parasite density, age and year of sample collection.
Results: The level of varC and PfSir2a transcripts was higher in P. falciparum isolates from afebrile individuals
(P≤0.006), while varB and DC8 genes (P≤0.002) were higher in isolates from individuals with febrile infections. After
adjusting the analysis by area of residence, doubling the relative transcript unit (RTU) of varC and PfSir2a was associated with a 29.7 (95% CI 4.6–192.3) and 8.5 (95% CI 1.9–32.2) fold increases, respectively, of the odds of being afebrile.
In contrast, doubling the RTU of varB and DC8 was associated with a 0.8 (95% CI 0.05–0.6) and 0.2 (95% CI 0.04–0.6)
fold changes, respectively, of the odds of being afebrile. No signifcant diferences were found for Pfs25 transcript
levels in P. falciparum isolates from afebrile and febrile individuals.
Conclusions: var and gametocyte-specifc transcript patterns in febrile and afebrile infections from southern
Mozambique matched by age, parasite density and recruitment period suggest similar transmissibility but diferential
expression of variant antigens involved in cytoadhesion and immune-evasion.
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GUPTA, Himanshu, et al. Differential expression of var subgroups and PfSir2a genes in
afebrile Plasmodium falciparum malaria: a matched case-control
study. Malaria Journal. 2019. Vol. 18. ISSN 1475-2875. [consulted: 13 of June of 2026]. Available at: https://hdl.handle.net/2445/141198