Human got a new biotic friend to combat against Dengue

Dr.Amresh kumar sharma

Asst.Prof(Bioinformatics)

Dengue is well known and most common disease. It is transmitted by mosquito-virus. As this is caused by viruses living inside the arthropods and spread through them, it is called arboviral disease. It possesses a significant global health concern worldwide. Dengue is known to us with various names such as 7-day fever or breakbone. Several symptoms are fever with high intensity, pain in muscles and joint, head pain near or behind the eyes, vomiting, skin rashes, and when it grows to severity then symptoms are abdominal pain, rapid breathing, fatigue, blood in stool, thirst, change in skin condition, and weakness (Fig.1(A)). Dengue records for approx or over 100 million cases annually, and 20 to 25 thousand mortalities globally. The mosquitoes that carry dengue viruses are Aedes (female only)—Aedes aegypti and Aedes albopictus (Fig.1(B)). These viruses are commonly known as dengue virus (DNV) and dengue haemorrhagic fever (DHF)[1-3].

Biotic friend – Wolbachia

In search of remedy for dengue, we got a new biotic friend of bacterial origin from genus Wolbachia, named as Wolbachia pipientis.  They are from an intracellular bacterial group, which belongs to order Rickettsiales, and it is also very much diversified. They are host manipulators, and the most important feature of these bacteria are ability to live inside and alters the processes of cellular and germ line or reproductive in invertebrates. They cause manipulation to host genetics by various modes such as parthenogenesis (P), (CI) or cytoplasmic incompatibility, male killing or (MK), and feminization or (F). They show two types of life style within the host: one is parasitic when they infect arthropods and another type is mutualist when they infect nematodes. It is believed that they spread their infection in arthropods over 60% [6-7]. Most commonly observed Wolbachia image taken by Scott O’Neill bellow in (Fig. 2).

Why it’s a friend?

Female Aedes mosquito carries dengue viruses within their bodies and spread infections from one individual to others. Wolbachia, if possibly infect these mosquitoes, then these mosquitoes are unable to carry dengue virus [9]. This makes us to come to conclusion that Wolbachia can help to develop an environment which is free from dengue carrying mosquitoes. This hypothesis makes these bacteria as biotic friend of us. It was discovered that that Wolbachia stops dengue viruses from growing in the bodies of mosquitoes.

How it works against dengue?

Mosquitoes spread diseases by picking up dengue viruses by biting infected persons. They transmit the virus to the next person, whenever they bite again. Wolbachia are very common bacteria occurring naturally and infects species of insects, which include some mosquitoes. Wolbachia found to live within the insect cells. They transmit from one generation to the next through vertical transmission and they are maternally inherited. During the research, it was found that Wolbachia is safe for humans. Aedes mosquito does not carry these bacteria naturally. Wolbachia is found to blocks dengue viruses from growing and surviving inside the bodies of Aedes mosquitoes. This can be concluded that mosquitoes with Wolbachia infection have less ability or almost lost the ability to transmit virus. As per World Mosquito Program, Wolbachia induced Aedes mosquitoes breed and released in affected area to control viral transmission. It was observed that there is a tremendous decrease in dengue cases. Wolbachia are in contact with humans through the foods and the insects bite, but no health risks have been observed. Food chains and other ecological impacts have been observed but no sever impact is seen. Independent risk assessments studied by WMP’s Wolbachia technology in Colombia, Australia, Vietnam, and Indonesia, and found no risk associated with it [10].

References

1. Baak-Baak CM, et al. (2019). Entomological and virological surveillance for dengue virus in churches in Merida, Mexico. Rev Inst Med Trop Sao Paulo. 61: e9.
2. Sharma M, et al. (2020). Magnitude and Functionality of the NS1-Specific Antibody Response Elicited by a Live-Attenuated Tetravalent Dengue Vaccine Candidate. J Infect Dis. 221(6): 867-877.
3. Oliveira LNDS, Itria A, Lima EC. (2019). Cost of illness and program of dengue: A systematic review. PLoS One. 14(2): e0211401. 
4. https://continentalhospitals.com/blog/dengue-fever-symptoms-causes-and-treatment/.
5. https://www.healthshots.com/disease/dengue/.
6. Werren J, Baldo L, Clark M. (2008). Wolbachia:master manipulators of invertebrate biology. Nat Rev Microbiol 6. 741–751.
7. Hilgenboecker K, Hammerstein P, Schlattmann P, et al. (2008). How many species are infected with Wolbachia?–A statistical analysis of current data. FEMS Microbiol Lett. 281(2): 215-20.
8. Source: https://doi.org/10.1371/journal.pbio.0020076.
9. Fox T, et al. (2023). Wolbachia‐carrying Aedesmosquitoes for preventing dengue infection. Cochrane Database Syst Rev. 2023(3): CD015636.
10. https://www.worldmosquitoprogram.org/en/work/wolbachia-method/how-it-works.