New Drug for Amoebiasis

• 15 Jun 2020

Why in News

Recently, researchers from the Jawaharlal Nehru University (JNU) have developed new drug molecules against the protozoa ‘Entamoeba histolytica’ that causes amoebiasis.

Key Points

• The Protozoa and High Oxygen Level:
  
  • The protozoa is anaerobic or microaerophilic in nature such that it cannot survive high concentrations of oxygen.
    
    • Anaerobic organisms are those who exist in the absence of free oxygen.
    • A microaerophilic atmosphere is ideal for a microorganism that can grow under reduced oxygen and increased carbon dioxide levels.
  • However, during infection, it faces a high surge of oxygen inside the human body. The organism synthesizes large amounts of cysteine to counter oxidative stress.
• Synthesis of Cysteine:
  
  • This pathogen deploys cysteine as one of the essential molecules in its defence mechanism against high oxygen levels. It expresses two crucial enzymes for synthesizing cysteine.
    
    • Cysteines are enzymes that degrade proteins in the body.
    • Cysteine biosynthesis is crucial for the survival of E. histolytica and for similar protozoan parasites.
• JNU Research:
  
  • Researchers have characterized and determined the molecular structures of both the crucial enzymes.
  • They have also successfully screened for potent inhibitors for one of the enzymes, O-acetyl L-serine sulfhydrylase (OASS).
  • Some of these inhibitors can check the growth of this organism with high efficacy by targeting their pathways.
  • The identified molecules can lead to the development of drug molecules.

Protozoa

• Protozoans are the single-celled eukaryotes, either free-living or parasitic, which feed on organic matter such as other microorganisms or organic tissues and debris.
  
  • Eukaryotes are organisms whose cells have a nucleus enclosed within membranes, unlike prokaryotes, which have no membrane-bound organelles.
  • A parasite is an organism that lives on or in a host and gets its food from or at the expense of its host. E.g. plasmodium parasite which causes malaria.
• Habitat: Mostly they are aerobic (with oxygen) but some are anaerobic (without oxygen) and present in the rumen or human intestine.
• Size and Shape: The size and shape of Protozoa vary greatly, from microbial (1µm) to large enough and can be seen by the naked eye.
• Nutrition: Protozoans are heterotrophs and have holozoic nutrition.
  
  • Holozoic nutrition can be defined as a method of nutrition which involves the ingestion of some complex organic substances (such as parts of a plant or animal) that may be in the solid or the liquid form.

Entamoeba histolytica

• According to the World Health Organization (WHO), Entamoeba histolytica is the third-leading cause of morbidity and mortality due to parasitic disease in humans.
  
  • Predominantly infecting humans and other primates, E. histolytica is estimated to infect about 35-50 million people worldwide.
  • A parasitic disease is an infectious disease caused or transmitted by a parasite. E.g. Malaria.
• It causes amoebiasis or amoebic dysentery, which is highly prevalent in developing countries.

Amoebiasis

• It is a disease caused by the parasite Entamoeba histolytica.
• Amoebiasis infection is most common in tropical areas with untreated water. E.g. India.
• It spreads through drinking or eating uncooked food, such as fruit, that may have been washed in contaminated local water.
• If symptoms occur, they may be mild and include cramping and diarrhoea.
• It can be treated through antibiotics.

Source: PIB