Wildlife Tuberculosis: An Emerging Threat for Conservation in South Asia

Wildlife tuberculosis (TB) is becoming one of the emerging challenges for conservation globally. South Asian region is home to many endangered species like Asian elephants, rhinoceros, and Bengal tigers. Although it carries more than one‐third of global burden of human TB, TB in livestock and wildlife has not been adequately studied. This chapter reviews the present knowledge and information about animal‐adapted members of Mycobacterium tuberculosis complex and wildlife TB in South Asia. Recent studies of TB from different wild animals in Nepal and Bangladesh have found that M.orygis is an emerging threat of wildlife TB in the region. These studies have demonstrated wide diversity of M. orygis strains circulating in the region indicating its endemic distribution. M. orygis–associated TB was discovered from a free‐ranging rhinoceros in Nepal and the finding could signify threat of TB in other wild animals, including a possibility of unknown maintenance host. Recent studies also revealed an emerging challenge caused by TB to elephants in different South Asian countries like Nepal, India, and Sri Lanka. Wildlife TB is becoming a conservation challenge in South Asia, but given the paucity of research in this area, it is overlooked and underexplored

Molecular characterization of Mycobacterium orygis isolates from wild animals of Nepal

Mycobacterium orygis, a new member of the Mycobacterium tuberculosis complex, was isolated from a captive spotted deer (Axis axis) and a blue bull (Boselaphus tragocamelus) in Nepal. Analyses by spoligotyping, mycobacterial interspersed repetitive units-variable number of tandem repeats (MIRU-VNTR) typing, region of difference and single nucleotide polymorphism of genes gyrB, mmpL6, TbD1, PPE55 and Rv2042c confirmed the isolates as M. orygis. Moreover, analyses by spoligotyping (SIT587) as well as MIRU-VNTR showed that the isolates shared a similar pattern with many reported isolates. From previous and the present studies, it can be inferred that South Asia is one of the endemic regions for M. orygis. Further investigation including a larger sample size and different host interaction will help to understand the ecology and epidemiology of M. orygis in Nepal

Wild ciliates differ in susceptibility to Legionella pneumophila JR32

We investigated how Legionella pneumophila (Lp) JR32 interacts with Anteglaucoma CS11A and Colpoda E6, two ciliates that we isolated from sewage and sink trap sludge, respectively, using a handmade maze device containing a 96-well crafting plate. Our 185 rDNA-based phylogenetic analysis showed that Anteglaucoma CS11A and Colpoda E6 formed distinct clades. Scanning electron microscopy showed that Anteglaucoma CS11A had a bigger-sized body than Colpoda E6 and, unlike Tetrahymena IB (the reference strain), neither ciliate produced pellets, which are extracellular vacuoles. Fluorescence microscopic observations revealed that although the intake amounts differed, all three ciliates rapidly ingested LpJR32 regardless of the presence or absence of the icm/dot virulence genes, indicating that they all interacted with LpJR32. In co-cultures with Anteglaucoma CS11A, the LpJR32 levels were maintained but fell dramatically when the co-culture contained the LpJR32 icm/dot deletion mutant instead. Anteglaucoma CS11 A died within 2days of co-culture with LpJR32, but survived co-culture with the deletion mutant. In co-cultures with Colpoda E6, LpJR32 levels were maintained but temporarily decreased independently of the virulence gene. Concurrently, the Colpoda E6 ciliates survived by forming cysts, which may enable them to resist harsh environments, and by diminishing the sensitivity of trophozoites to Lp. In the Tetrahymena IB co-cultures with LpJR32 or Delta icm/dot, the Lp levels were maintained, albeit with temporal decreases, and the Tetrahymena IB levels were also maintained. We conclude that unlike Tetrahymena IB with pellet production, Anteglaucoma CS11A can be killed by LpJR32 infection, and Colpoda E6 can resist LpJR32 infection through cyst formation and the low sensitivity of trophozoites to Lp. Thus, the two ciliates that we isolated had different susceptibilities to LpJR32 infection

Chlamydia trachomatis relies on the scavenger role of aryl hydrocarbon receptor with detyrosinated tubulin for its intracellular growth, but this is impaired by excess indole

Although IFN-γ depletes tryptophan (Trp) as a defense against intracellular Chlamydia trachomatis (Ct) infected to hypoxic vagina, the presence of indole, a precursor of Trp, enables Ct to infect IFN-γ-exposed culture cells. Meanwhile, Trp-derived indole derivatives interact the aryl hydrocarbon receptor (AhR), which is a ligand-dependent transcription factor involved in the cellular homeostasis with tubulin dynamics. Here, the amounts of IFN-γ and indole in cervical swabs with known Ct infection status were measured, and Ct growth in the presence of indole was determined from the perspective of the AhR axis under hypoxia. A positive correlation between the amounts of IFN-γ and indole was found, and both of these amounts were lower in Ct-positive swabs than in Ct-negative ones. Indole as well as other AhR ligands inhibited Ct growth, especially under normoxia. Ct prompted the expression of detyrosinated tubulin (dTTub), but indole inhibited it. Indole did not stimulate the translocation of AhR to nucleus, and it blocked AhR activation in AhR-reporter cells. Ct growth was reduced more effectively under normoxia in AhR-knockdown cells, an effect that was enhanced by indole, which in turn diminished dTTub. Thus, Ct growth relies on the scavenger role of cytosolic AhR responsible for promoting dTTub expression

Characterization of embB mutations involved in ethambutol resistance in multi-drug resistant Mycobacterium tuberculosis isolates in Zambia

Background: Ethambutol (EMB) is an important anti-tuberculosis drug used in the management of multi-drug resistant tuberculosis (MDR-TB). Mutations in embB are the major mechanism of resistance. This study investigated embB mutations among MDR-TB isolates and analyzed their correlations with phenotypic drug susceptibility testing (DST) in Zambia. Method: A total of 132 MDR-TB isolates were collected from January 2014 to April 2017 and characterized using MGIT 960 systems, embB sequencing, and spoligotyping. Results: Out of 61 phenotypically EMB resistant isolates, 53 had mutations in embB. Among the 71 EMB susceptible isolates, 47 had embB mutations. Sensitivity of embB mutations was 86.9% while specificity was 33.8%. CAS1_Kili (SIT21) had high odds of having embB mutations, particularly, G918A (Met306eIl) (Odds ratio 16.7, p < 0.0001). Conclusion: Molecular EMB resistance testing by DNA sequencing can improve detection of EMB resistance among MDR-TB patients in Zambia. Additionally, CAS1_Kili was associated with embB amino acid substitution Met306Ile suggesting transmission. A detailed investigation to track and determine transmission hotspot area for MDR-TB could help optimize control strategies