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| LETTER TO EDITOR |
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| Year : 2022 | Volume
: 15
| Issue : 4 | Page : 186-187 |
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A hypothetical mechanism whereby malaria infection protects against COVID-19
Reza Rastmanes
| Date of Submission | 20-Feb-2022 |
| Date of Decision | 30-Mar-2022 |
| Date of Acceptance | 07-Apr-2022 |
| Date of Web Publication | 13-Apr-2022 |
Correspondence Address:
Reza Rastmanes
 Source of Support: None, Conflict of Interest: None
DOI: 10.4103/1995-7645.340575
How to cite this article:
Rastmanes R. A hypothetical mechanism whereby malaria infection protects against COVID-19. Asian Pac J Trop Med 2022;15:186-7 |
The author is an independent researcher who is a member of Advisory Board of the Nutrition Society, London, UK and also a member of the American Physical Society, USA
I would like to add new findings in support of a novel hypothesis stating that malaria infection may protect against COVID-19[1],[2],[3]. As this might facilitate understanding the underlying mechanism behind this association, the discovery of better preventive measures and therapeutic agents for the management of this terrible pandemic.
Just very recently, Huang et al.[4] provided the first experimental data to investigate the capacity of SARS-CoV-2 to infect and the virus is likely to be transmitted by mosquitoes. They showed that even under extreme conditions, SARS-CoV-2 is unable to replicate in most widely distributed mosquitoes namely Aedes (Ae.) aegypti, Ae. albopictus and Culex quinquefasciatus; therefore, the virus cannot be transmitted to people even in the unlikely event that a mosquito feeds upon a viremic host. Interestingly, in endemic areas where individuals experience repeated Plasmodium falciparum infections over many years, it is shown that monocytes of malaria- infected adults produce more IL-10 and express higher levels of the regulatory molecules CD163, CD206, Arginase-1 and TGM2, suggesting that past malaria exposure most possibly mitigated monocyte-associated immunopathology induced by other pathogens such as SARS-CoV-2[5].
Furthermore, Foo et al. recently showed that AEG12, a type of mosquito protein, is up-regulated in response to blood meals and flavivirus infection. AEG12 displays cytolytic and hemolytic activity by selectively delivering unsaturated fatty acid cargoes into phosphatidylcholine-rich lipid bilayers. Meanwhile, this property enables AEG12 to inhibit replication of coronaviruses. This novel finding unveils the mechanistic understanding of AEG12 function and provides the necessary implications for AEG12 possible application as a broad-spectrum therapeutic against cellular and viral targets[6].
Saliva of anopheline mosquitoes carries several antihemostatic compounds such as anophelins which are regarded as small protein thrombin inhibitors[7]. Another similar in-depth structural and functional analyses yielded detailed novel insights into the mechanism of thrombin inhibition by the antihemostatic salivary protein cE5 from mosquitoes such as Anopheles gambiae[8]. There are numerous studies reporting anti-thrombin property from other mosquitoes such as Anopheles albimanus saliva[9].
[Figure 1] illustrates a consolidated update of the hypothetical pathways by which repeated malaria-infection might protect against COVID-19. | Figure 1: Hypothetical pathways whereby repeated malaria-infection might protect against COVID-19.
Click here to view |
If this hypothesis[3] proves to be true, it will have deep environmental implications. For example, extensive mosquito control/elimination programs might have theoretically resulted in rapid rise in incidence and prevalence of COVID-19 in malaria- endemic areas. China implemented an extensive malaria elimination program in Hubei Province between 2005 and 2016[10], with Wuhan as the central outbreak point and capital city, I question whether mosquito elimination programs in China can meanwhile causally predispose the population to COVID-19 corollary to being malaria-naïve? Though this seems to be implausible-because besides Wuhan, many other provinces also implemented extensive mosquito control/ elimination programs-this question may merit further research both retrospectively (by data analysis) and prospectively (by proper designs) and may be insightful for researchers.
Conflict of interest statement
The author declares that there is no conflict of interest.
Funding
The author received no extramural funding for the study.
Author’s contributions
R.R. developed the theoretical formalism and fully contributed to the writing of the letter.
| References | |  |
| 1. | Iesa MAM, Osman MEM, Hassan MA, Dirar AIA, Abuzeid N, Mancuso JJ, et al. SARS-CoV-2 and Plasmodium falciparum common immunodominant regions may explain low COVID-19 incidence in the malaria-endemic belt. New Microbes New Infect 2020; 38: 100817.  |
| 2. | Panda AK, Tripathy R, Das BK. Plasmodium falciparum infection may protect a population from severe acute respiratory syndrome coronavirus 2 infection. J Infect Dis 2020; 222: 1570-1571. |
| 3. | Parodi A, Cozzani E. Coronavirus disease 2019 (COVID-19) and malaria: Have anti glycoprotein antibodies a role? Med Hypotheses 2020; 143: 110036. |
| 4. | Huang YS, Vanlandingham DL, Bilyeu AN, Sharp HM, Hettenbach SM, Higgs S. SARS-CoV-2 failure to infect or replicate in mosquitoes: An extreme challenge. Sci Rep 2020; 10: 11915. |
| 5. | Guha R, Mathioudaki A, Doumbo S, Doumtabe D, Skinner J, Arora G, et al. Plasmodium falciparum malaria drives epigenetic reprogramming of human monocytes toward a regulatory phenotype. PLoS Pathog 2021; 17: e1009430. |
| 6. | Foo ACY, Thompson PM, Chen SH, Jadi R, Lupo B, DeRose EF, et al. The mosquito protein AEG12 displays both cytolytic and antiviral properties via a common lipid transfer mechanism. Proc Natl Acad Sci U S A 2021; 118(11): e2019251118. doi: 10.1073/pnas.2019251118. |
| 7. | Watson EE, Liu X, Thompson RE, Ripoll-Rozada J, Wu M, Alwis I, et al. Mosquito-derived anophelin sulfoproteins are potent antithrombotics. ACS Cent Sci 2018; 4: 468-476. |
| 8. | Pirone L, Ripoll-Rozada J, Leone M, Ronca R, Lombardo F, Fiorentino G, et al. Functional analyses yield detailed insight into the mechanism of thrombin inhibition by the antihemostatic salivary protein cE5 from Anopheles gambiae. J Biol Chem 2017; 292: 12632-12642. |
| 9. | Valenzuela JG, Francischetti IM, Ribeiro JM. Purification, cloning, and synthesis of a novel salivary anti-thrombin from the mosquito Anopheles albimanus. Biochemistry 1999; 38: 11209-11215. |
| 10. | Xia J, Huang X, Sun L, Zhu H, Lin W, Dong X, et al. Epidemiological characteristics of malaria from control to elimination in Hubei Province, China, 2005-2016. Malar J 2018; 17: 81. |
[Figure 1]
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