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Foo, C. S.

Publications and source records attributed to Foo, C. S..

6 recordsLinked to original sources

Unified Genomic and Chemical Representations Enable Bidirectional Bio-synthetic Gene Cluster and Natural Product Retrieval

Natural product discovery is increasingly driven by the ability to analyze microbial genomes for biosynthetic gene clusters (BGCs) that encode secondary metabolites. While existing approaches have successfully linked BGCs to broad classes of chemical products, they typically operate in a single modality (genomic or chemical) limiting the scope of bidirectional prediction. In this work, we propose a multimodal framework that integrates genomic and chemical information by projecting embeddings derived from pretrained language models into a common representation space. We embed genomic sequences using a BGC foundation model and represent molecules through a chemical language model, then use a metric learning model to co-embed BGCs and their associated chemical structures. This co-embedding space allows us to quantify the similarity between BGCs and compounds using similarity measures, enabling both forward and inverse retrieval tasks. Beyond retrieval, we show that the shared space can guide strain selection for targeted compounds. By identifying BGCs closest to a query compound in the embedding space, we prioritize microbial strains that encode similar clusters, thereby streamlining genome mining and retrobiosynthetic design efforts. This approach represents a generalizable, scalable strategy to bridge biological and chemical modalities in natural product discovery.

synthetic biology↗

A SCID mouse model to evaluate the efficacy of antivirals against SARS-CoV-2 infection

Ancestral SARS-CoV-2 lacks the intrinsic ability to bind to the mouse ACE2 receptor and therefore establishment of SARS-CoV-2 mouse models has been limited to the use of mouse-adapted viruses or genetically modified mice. Interestingly, some of the variants of concern, such as the beta B.1.351 variant, show an improved binding to the mouse receptor and hence better replication in different Wild type (WT) mice species. Here, we desribe the establishment of SARS-CoV-2 beta B.1.351 variant infection model in male SCID mice as a tool to assess the antiviral efficacy of potential SARS-CoV-2 small molecule inhibitors. Intranasal infection of male SCID mice with 105 TCID50 of the beta B.1.351 variant resulted in high viral loads in the lungs and moderate signs of lung pathology on day 3 post-infection (pi). Treatment of infected mice with the antiviral drugs Molnupiravir (200 mg/kg, BID) or Nirmatrelvir (300 mg/kg, BID) for 3 consecutive days significantly reduced the infectious virus titers in the lungs by 1.9 and 3.8 log10 TCID50/mg tissue, respectively and significantly improved lung pathology. Together, these data demonstrate the validity of this SCID mice/beta B.1.351 variant infection model as a convenient preclinical model for assessment of potential activity of antivirals against SARS-CoV-2. ImportanceUnlike the ancestral SARS-CoV-2 strain, the beta (B.1.351) VoC has been reported to replicate to some extent in WT mice (species C57BL/6 and BALB/c). We here demonstrate that infection of SCID mice with SARS-CoV-2 beta variant results in high viral loads in the lungs on day 3 post-infection (pi). Treatment of infected mice with the antiviral drugs Molnupiravir or Nirmatrelvir for 3 consecutive days markedly reduced the infectious virus titers in the lungs and improved lung pathology. The advantages of using this mouse model over the standard hamster infection models to assess the in vivo efficacy of small molecule antiviral drugs are (i) the use of a clinical isolate without the need to use mouse-adapted strains or genetically modified animals (ii) lower amount of the test drug is needed and (ii) more convenient housing conditions compared to bigger rodents such as hamsters.

microbiology↗

Full protection against all four SARS-CoV-2 variants of concern (VOC) in hamsters requires revision of spike antigen used for vaccination.

Current first-generation COVID-19 vaccines are based on prototypic spike sequences from ancestral 2019 SARS-CoV-2 strains. However, the ongoing pandemic is fueled by variants of concern (VOC) that threaten to escape vaccine-mediated protection. Here we show in a stringent hamster model that immunization using prototypic spike expressed from a potent YF17D viral vector (1) provides vigorous protection against infection with ancestral virus (B lineage) and VOC Alpha (B.1.1.7), however, is insufficient to provide maximum protection against the Beta (B.1.351) variant. To improve vaccine efficacy, we created a revised vaccine candidate that carries an evolved spike antigen. Vaccination of hamsters with this updated vaccine candidate provides full protection against intranasal challenge with all four VOCs Alpha, Beta, Gamma (P.1) and Delta (B.1.617.2) resulting in complete elimination of infectious virus from the lungs and a marked improvement in lung pathology. Vaccinated hamsters did also no longer transmit the Delta variant to non-vaccinated sentinels. Hamsters immunized with our modified vaccine candidate also mounted marked neutralizing antibody responses against the recently emerged Omicron (B.1.1.529) variant, whereas the old vaccine employing prototypic spike failed to induce immunity to this antigenically distant virus. Overall, our data indicate that current first-generation COVID-19 vaccines need to be urgently updated to cover newly emerging VOCs to maintain vaccine efficacy and to impede virus spread at the community level. Significance StatementSARS-CoV-2 keeps mutating rapidly, and the ongoing COVID-19 pandemic is fueled by new variants escaping immunity induced by current first-generation vaccines. There is hence an urgent need for universal vaccines that cover variants of concern (VOC). In this paper we show that an adapted version of our vaccine candidate YF-S0* provides full protection from infection, virus transmission and disease by VOCs Alpha, Beta, Gamma and Delta, and also results in markedly increased levels of neutralizing antibodies against recently emerged Omicron VOC in a stringent hamster model. Our findings underline the necessity to update COVID-19 vaccines to curb the pandemic, providing experimental proof on how to maintain vaccine efficacy in view of an evolving SARS-CoV-2 diversity.

microbiology↗

ALG-097111, a potent and selective SARS-CoV-2 3-chymotrypsin-like cysteine protease inhibitor exhibits in vivo efficacy in a Syrian Hamster model

O_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY C_FIG_DISPLAY There is an urgent need for antivirals targeting the SARS-CoV-2 virus to fight the current COVID-19 pandemic. The SARS-CoV-2 main protease (3CLpro) represents a promising target for antiviral therapy. The lack of selectivity for some of the reported 3CLpro inhibitors, specifically versus cathepsin L, raises potential safety and efficacy concerns. ALG-097111 potently inhibited SARS-CoV-2 3CLpro (IC50 = 7 nM) without affecting the activity of human cathepsin L (IC50 > 10 M). When ALG-097111 was dosed in hamsters challenged with SARS-CoV-2, a robust and significant 3.5 log10 (RNA copies/mg) reduction of the viral RNA copies and 3.7 log10 (TCID50/mg) reduction in the infectious virus titers in the lungs was observed. These results provide the first in vivo validation for the SARS-CoV-2 3CLpro as a promising therapeutic target for selective small molecule inhibitors.

microbiology↗

Nelfinavir markedly improves lung pathology in SARS-CoV-2-infected Syrian hamsters despite a lack of an antiviral effect

In response to the ongoing COVID-19 pandemic, repurposing of drugs for the treatment of SARS-CoV-2 infections is being explored. The HIV protease inhibitor Nelfinavir, widely prescribed in combination with other HIV inhibitors, has been shown to inhibit in vitro SARS-CoV-2 replication. We here report on the effect of Nelfinavir in the Syrian hamster SARS-CoV-2 infection model. Although treatment of infected hamsters with either 15 or 50 mg/kg BID Nelfinavir [for four consecutive days, initiated on the day of infection] does not reduce viral RNA loads nor infectious virus titres in the lungs compared to the vehicle control, the drug reduced virus-induced lung pathology to nearly the baseline scores of healthy animals. A substantial interstitial infiltration of neutrophils is observed in the lungs of treated (both infected and uninfected) animals. The protective effect of Nelfinavir on SARS-CoV-2-induced lung pathology (at doses that are well tolerated and that result in exposures nearing those observed in HIV-infected patients) may lay the foundation for clinical studies with this widely used drug.

microbiology↗

Molnupiravir (EIDD-2801) inhibits SARS-CoV2 replication in Syrian hamsters model

Favipiravir and Molnupiravir, orally available antivirals, have been reported to exert antiviral activity against SARS-CoV2. In recent days preliminary efficacy data have been reported in COVID-19 patients. We here studied the combined antiviral effect of the drugs in the SARS-CoV2 hamster infection model. We first demonstrate that Molnupiravir can reduce infectious virus titers in lungs of infected animals in a dose-dependent manner by up to 3.5 log10 which is associated with a marked improvement of virus-induced lung pathology. When animals are treated with a combination of suboptimal doses of Molnupiravir and Favipiravir (that each alone result in respectively a 1.3 log10 and 1.1 log10 reduction of infectious virus titers in the lungs), a marked combined potency is observed. Infectious virus titers in the lungs of animals treated with the combo are on average reduced by 4.5 log10 and infectious virus are no longer detected in the lungs of 60% of treated infected animals. Both drugs result in an increased mutation frequency of the remaining viral RNA recovered from the lungs. In the combo-treated hamsters an increased frequency of C-to-T and G-to-A mutations in the viral RNA is observed as compared to the single treatment groups which may explain the pronounced antiviral potency of the combination. Our findings may lay the basis for the design of clinical studies to test the efficacy of the combination of Molnupiravir and Favipiravir in the treatment of COVID-19.

microbiology↗