Live biotherapeutic throat spray for respiratory virus inhibition and interferon pathway induction

Abstract

Respiratory viruses such as influenza viruses, respiratory syncytial virus (RSV), and coronaviruses initiate infection at the mucosal surfaces of the upper respiratory tract (URT), where the resident respiratory microbiome has an important gatekeeper function. In contrast to gut-targeting administration of beneficial bacteria against respiratory viral disease, topical URT administration of probiotics is currently underexplored, especially for the prevention and/or treatment of viral infections. Here, we report the selection and formulation of a broad-acting throat spray with live lactobacilli which induce interferon regulatory pathways and are able to inhibit respiratory viruses. Rational selection of Lactobacillaceae strains was based on safety, applicability, and potential antiviral and immunostimulatory efficacy in the URT. Three strains, Lacticaseibacillus casei AMBR2, Lacticaseibacillus rhamnosus GG and Lactiplantibacillus plantarum WCFS1 significantly reduced the cytopathogenic effects of RSV, influenza A/H1N1 and B viruses, and HCoV-229E coronavirus in co-culture models with bacteria, virus and host cells. Subsequently, these strains were formulated in a throat spray and human monocytes were employed to confirm the formulation process did not reduce the interferon regulatory pathway-inducing capacity. Administration of the throat spray in healthy volunteers revealed that the lactobacilli were capable of temporary colonization of the throat in a metabolically active form.

Randomized, Double-Blind, Placebo-Controlled Trial of a Throat Spray with Selected Lactobacilli in COVID-19 Outpatients

“…The second major finding of our work is the lower number of virus-positive test results at day 21, in line with the selected antiviral mode of action in vitro, where we showed that the selected lactobacilli could induce interferon regulatory pathways and reduce the cytopathic effects of coronaviruses and related respiratory viruses in cellular models (24). Due to the delay between testing and inclusion, most participants started within 2 to 5 days after the onset of their first symptoms, when the viral loads were the highest.…”

“…Indeed, the probiotic definition is not limited to the gut ( 23 ). We have recently developed an antiviral throat spray with three Lactobacillaceae strains that were selected based on their safety, their in vitro multifactorial modes of action on key aspects of viral infection and disease (including interferon activation and blocking of upper respiratory tract [URT] viral infection), and their ability to thrive in the human respiratory tracts of healthy volunteers ( 24 ). Yet microbiome therapy in patients with live bacteria has several challenges, such as formulations, regulation, and selection of the target patient population.…”

“…Here, we evaluated the clinical potential of this multispecies probiotic throat spray with Lacticaseibacillus casei AMBR2, Lacticaseibacillus rhamnosus GG, and Lactiplantibacillus plantarum WCFS1 against COVID-19 in a randomized, double-blind, placebo-controlled trial in unvaccinated COVID-19 outpatients exhibiting mild-to-moderate symptoms. The formulation with L. casei AMBR2, L. rhamnosus GG, and L. plantarum WCFS1 was developed based on the safety, applicability, and experimentally observed functional characteristics of several strains screened (immunostimulation, direct antiviral action, and epithelial barrier maintenance), as described in detail previously ( 24 ). In this study, we monitored the impact of these previously selected strains in the spray on symptom severity, time to improvement, viral loads, anti-SARS-CoV-2 antibodies, and the respiratory microbiome in an out-of-hospital setting.…”

Evaluation of a throat spray with lactobacilli in COVID-19 outpatients in a randomized, double-blind, placebo-controlled trial for symptom and viral load reduction

“…Our results on the viral loads at day 21 are promising and in line with our previously reported in vitro data, where we showed that the microbiome members that were selected for the throat spray show clear antiviral effects against coronaviruses under controlled in vitro study set-ups [16]. In the trial with the oral probiotic L. plantarum strains and Pediococcus acidilactici KABP021, a significantly larger reduction in nasopharyngeal viral load was observed in the verum group at day 15 and day 30 (p < 0.001) [8].…”

“…Indeed, the probiotic definition is not limited to the gut [15]. We recently developed a microbiome-modulating throat spray with three Lactobacillaceae strains that were selected based on their safety and in vitro multifactorial modes of action on the key aspects of viral infection and disease, and their ability to thrive in the human respiratory tract of healthy volunteers [16]. Yet, microbiome therapy with live bacteria has several challenges, such as formulation and selection of target patient population.…”