Konzo, a distinct upper motor neuron disease associated with a cyanogenic diet and chronic malnutrition, predominately affects children and women of childbearing age in sub-Saharan Africa. While the exact biological mechanisms that cause this disease have largely remained elusive, host-genetics and environmental components such as the gut microbiome have been implicated. Using a large study population of 180 individuals from the Democratic Republic of the Congo, where konzo is most frequent, we investigate how the structure of the gut microbiome varied across geographical contexts, as well as provide the first insight into the gut flora of children affected with this debilitating disease using shotgun metagenomic sequencing. Our findings indicate that the gut microbiome structure is highly variable depending on region of sampling, but most interestingly, we identify unique enrichments of bacterial species and functional pathways that potentially modulate the susceptibility of konzo in prone regions of the Congo.

Gamma-interferon-inducible lysosomal thiol reductase (GILT) plays pivotal roles in both adaptive and innate immunities. GILT exhibits constitutive expression within antigen-presenting cells, whereas in other cell types, its expression is induced by interferon gamma (IFN-γ). Gaining insights into the precise molecular mechanism governing the induction of GILT protein by IFN-γ is of paramount importance for adaptive and innate immunities. In this study, we found that the 5′ segment of GILT mRNA inhibited GILT protein expression regardless of the presence of IFN-γ. Conversely, the 3′ segment of GILT mRNA suppressed GILT protein expression in the absence of IFN-γ, but it loses this inhibitory effect in its presence. Although the mTOR inhibitor rapamycin suppressed the induction of GILT protein expression by IFN-γ, the expression from luciferase sequence containing the 3′ segment of GILT mRNA was resistant to rapamycin in the presence of IFN-γ, but not in its absence. Collectively, this study elucidates the mechanism behind GILT induction by IFN-γ: in the absence of IFN-γ, GILT mRNA is constitutively transcribed, but the translation process is hindered by both the 5′ and 3′ segments. Upon exposure to IFN-γ, a translation inhibitor bound to the 3′ segment is liberated, and a translation activator interacts with the 3′ segment to trigger the initiation of GILT translation.

A high-risk infectious disease or a Category A pathogen, Lassa virus (LASV), requires strict containment, classified as biosafety level 4 (BSL-4) conditions, which restricts research on the virus due to the scarcity of BSL-4 facilities. Thus, replication-defective pseudotyped retroviral vectors have been widely used as safe materials for neutralizing activity assays of drugs and antibodies in BSL-2. Here, we established a novel retroviral vector system encoding LASV glycoprotein complex (GPC) that can exclusively replicate in cells expressing the Gag-Pol protein of murine leukemia virus (MLV) under BSL-2 conditions. Using this conditional replication system, we successfully isolated LASV GPC variants resistant to either an anti-LASV compound, lamellarin α 20-sulfate, or a neutralizing antibody derived from a Lassa fever survivor. In the lamellarin α 20-sulfate-resistant variants, K125E and H13R amino acid substitutions cooperatively conferred resistance. The K125E enhanced infectivity and simultaneously conferred a lethal effect on cells in the conditional replication system, while the H13R mitigated the latter effect, thereby enabling stable expression of LASV GPC in cells. In the neutralizing antibody-resistant variants, I403T substitution was responsible for the resistance by impairing antibody binding. This study provides a valuable BSL-2-based platform for isolating LASV GPC variants resistant to inhibitors and characterizing their mutations.

Host restriction factor GBP2 suppresses the replication of the ecotropic Moloney murine leukemia virus (E-MLV) by inhibiting furin protease, which cleaves the viral envelope glycoprotein (Env) into surface (SU) and transmembrane (TM) subunits. We analyzed the impacts of GBP2 on the infection efficiency mediated by MLV Envs of different strains of ecotropic Moloney, polytropic Friend, amphotropic, and xenotropic MLV-related (XMRV) viruses. Interestingly, the Envs of ecotropic Moloney and polytropic Friend MLV were sensitive to the antiviral activity of GBP2, while XMRV and amphotropic Envs showed resistance. Consistent with the sensitivity to GBP2, the amino acid sequences of the sensitive Envs at the SU-TM cleavage site were similar, as were the sequences of the resistant Envs. SU-TM cleavage of the GBP2-sensitive Env protein was inhibited by furin silencing, whereas that of GBP2-resistant Env was not. The substitution of the ecotropic Moloney cleavage site sequence with that of XMRV conferred resistance to both GBP2 and furin silencing. Reciprocally, the substitution of the XMRV cleavage site sequence with that of the ecotropic sequence conferred sensitivity to GBP2 and furin silencing. According to the SU-TM cleavage site sequence, there were sensitive and resistant variants among ecotropic, polytropic, and xenotropic MLVs. This study found that the dependence of MLV Env proteins on furin cleavage and GBP2-mediated restriction is determined by the amino acid sequences at the SU-TM cleavage site.