Implementation
According to the World Health Organization (WHO), about 24% of the human population — that is, over 1.5 billion people — is infected by soil-transmitted helminths (STH). Children from underprivileged areas in tropical and subtropical countries, with lack of adequate sanitation, are the most affected population — more than 800 million preschool- and school-age children live in areas of intense parasite transmission [1]. Despite the high prevalence worldwide, STH infections are still a neglected public health problem, and the majority of treatment approaches are based on mass administration of anthelmintic drugs.
However, as observed in livestock [2], and as an example of what happened with antibiotic-resistant bacteria, the intense reliance on chemotherapy programs can put pressure on parasite populations and potentially select drug-resistant genotypes. Even with the increasing warnings about the anthelmintic resistance phenomenon and how it could become a major challenge to human health due to intensive mass deworming policies, the establishment of effective alternative strategies to control helminth infection has not been implemented yet.
Many microorganisms have the feature of promoting health benefits when ingested in proper quantities. Some of the beneficial effects that these so-called probiotics can perform are the production of antimicrobial molecules, competition with pathogens for adhesion to the epithelium and nutrients, strengthening of the mucosal barrier integrity, immunomodulation, and production of metabolites of physiological importance, like coenzymes, short-chain fatty acids, amino and organic acids. Therefore, the positive effects of probiotics can lead to natural microbiota restoration and maintenance and nourishing improvements. Among probiotic bacteria, many species belong to the lactic acid bacteria group and are widely consumed through fermented foods, such as bacteria from Lactobacillus genus, used in yogurt, cheese, and other milk derivatives production, which are Gram-positive non-pathogenic, non-toxigenic bacteria [3].
Bearing in mind all the potential physiological benefits probiotics can exert and the fact that chitin is an important component of helminth’s cuticle and eggshell, we aimed to produce a chitinase-expressing probiotic bacterium as an alternative treatment to chemical anthelmintic. To that end, a Lactobacillus acidophilus strain was transformed both with endo- and exochitinase genes, in separate pools, containing a signal-peptide sequence so that the enzyme could be excreted by the cells.
Since latobacilli are widely used for fermented food production and also are frequently found in the human natural microbiota population, there shouldn’t be big safety concerns related to them. Furthermore, lactobacilli are fastidious bacteria with many nutritional requirements; therefore, they could hardly survive in an environment where nutrients are very scarce.
However, we have also designed two different kill switches to prevent any cell to survive once it is out of the human body.
Although light infections do not cause noticeable symptoms, helminthiases are frequently associated with nutritional issues in infected people. The worms inhabit and feed on the gastrointestinal tract, causing tissue damage, which leads to blood, iron, and protein losses, besides to nutrient malabsorption, commonly giving rise to anemia cases [1].
Therefore, our chitinase-expressing lactobacilli are aimed at helping populations of underprivileged, helminthiases endemic areas. Through a low-cost bioreactor — our hardware — appreciable amounts of bacteria can be easily grown by any person and distributed among community members in an appropriate dose to get all the benefits related to the probiotic, in addition to the anthelmintic treatment associated with it.
For the sake of accessibility of the biopharmaceutical for our intended users, we aim to collaborate with the government to distribute the product through the Brazilian public health system, taking it to the vulnerable population that cannot pay for a high-cost treatment. We can put this into practice by reaching out to the Ministry of Health and the Ministry of Science, Technology, and Innovation, in addition to seeking public-private partnerships, which can take our biopharmaceuticals to be consumed internationally.
For the implementation of our project, we would test the efficiency of our biodrug through a pre-clinical phase using a murine model. We aim to determine the appropriate dose, best pharmaceutical formulation for oral administration, possible effects, and the functionality of our kill switch model since it is a therapy designed for usage in humans and outside the controlled lab environment.
However, we would already have an estimated initial dose with the data obtained through mathematical modeling. In addition, we would also use our bioreactor to test the production of the probiotic bacteria on an industrial scale. Having a positive outcome in the pre-clinical phase, we will start a clinical trial to secure the safety and enable distribution for the population.
Orally administrated probiotics have a long journey after ingestion and before reaching small and large intestines. During gastrointestinal tract transit, cells face a variety of harsh conditions — like gastric acid, bile salts, and degrading enzymes — that can reduce their viability, which could in turn diminish the health benefits they can offer [4].
However, there are some means by which this can be overcome. It is common, for example, to encapsulate bacteria cells into microgel beads made of biopolymers, such as alginate, chitosan, cellulose derivatives, pectin, and gelatin; this reduces cells’ sensitivity to stressful environmental conditions [5]. As a mean to enhance our probiotic viability, we could administer it through an alginate-beads formulation, which is an easy-to-do and low-cost process. Or, alternatively, lactobacilli cells suspension could be freeze-dried to generate a final product that would be rehydrated by consumers at the time of consumption, dismissing the need for refrigeration, which would make long-term storage easier for underprivileged communities.
[1] World Health Organization. Soil-transmitted helminth infections. Available at:
[2] KAPLAN, R.M.; VIDYASHANKAR, A.N. An inconvenient truth: Global worming and anthelmintic resistance. Veterinary Parasitology, v. 186, n. 1, p. 70–78, 2012.
[3] MARÍA REMES-TROCHE, J.; et al. Lactobacillus acidophilus LB: a useful pharmabiotic for the treatment of digestive disorders. Therapeutic Advances in Gastroenterology, v. 13, 2020.
[4] HAN, S. et al. Probiotic Gastrointestinal Transit and Colonization After Oral Administration: A Long Journey. Frontiers in Cellular and Infection Microbiology, v. 11, 2021.
[5] YAO, M.; et al. Microencapsulation of Lactobacillus salivarious Li01 for enhanced storage viability and targeted delivery to gut microbiota. Food Hydrocolloids, v. 72, p. 228-236, 2017.