Evidence for Host-Bacterial Co-evolution via Genome Sequence Analysis of 480 Thai Mycobacterium tuberculosis Lineage 1 Isolates.

Tuberculosis presents a global health challenge. Mycobacterium tuberculosis is divided into several lineages, each with a different geographical distribution. M. tuberculosis lineage 1 (L1) is common in the high-burden areas in East Africa and Southeast Asia. Although the founder effect contributes significantly to the phylogeographic profile, co-evolution between the host and M. tuberculosis may also play a role. Here, we reported the genomic analysis of 480 L1 isolates from patients in northern Thailand. The studied bacterial population was genetically diverse, allowing the identification of a total of 18 sublineages distributed into three major clades. The majority of isolates belonged to L1.1 followed by L1.2.1 and L1.2.2. Comparison of the single nucleotide variant (SNV) phylogenetic tree and the clades defined by spoligotyping revealed some monophyletic clades representing EAI2_MNL, EAI2_NTM and EAI6_BGD1 spoligotypes. Our work demonstrates that ambiguity in spoligotype assignment could be partially resolved if the entire DR region is investigated. Using the information to map L1 diversity across Southeast Asia highlighted differences in the dominant strain-types in each individual country, despite extensive interactions between populations over time. This finding supported the hypothesis that there is co-evolution between the bacteria and the host, and have implications for tuberculosis disease control

A novel Ancestral Beijing sublineage of Mycobacterium tuberculosis suggests the transition site to Modern Beijing sublineages.

Global Mycobacterium tuberculosis population comprises 7 major lineages. The Beijing strains, particularly the ones classified as Modern groups, have been found worldwide, frequently associated with drug resistance, younger ages, outbreaks and appear to be expanding. Here, we report analysis of whole genome sequences of 1170 M. tuberculosis isolates together with their patient profiles. Our samples belonged to Lineage 1-4 (L1-L4) with those of L1 and L2 being equally dominant. Phylogenetic analysis revealed several new or rare sublineages. Differential associations between sublineages of M. tuberculosis and patient profiles, including ages, ethnicity, HIV (human immunodeficiency virus) infection and drug resistance were demonstrated. The Ancestral Beijing strains and some sublineages of L4 were associated with ethnic minorities while L1 was more common in Thais. L2.2.1.Ancestral 4 surprisingly had a mutation that is typical of the Modern Beijing sublineages and was common in Akha and Lahu tribes who have migrated from Southern China in the last century. This may indicate that the evolutionary transition from the Ancestral to Modern Beijing sublineages might be gradual and occur in Southern China, where the presence of multiple ethnic groups might have allowed for the circulations of various co-evolving sublineages which ultimately lead to the emergence of the Modern Beijing strains

PULSED FIELD GEL ELECTROPHORESIS ANALYSIS OF VIBRIO CHOLERAE ISOLATES IN SOUTHERN THAILAND

Abstract. Forty isolates of V. cholorae O1, O139 and non-O1/non-O139 collected from outbreaks in Songkhla and Phuket Provinces of southern Thailand during 1999-2001 and sporadic cases from different regions of Thailand during 1993-2002 were characterized using pulsed field gel electrophoresis (PFGE). Digestion of chromosomal DNA of the V. cholerae isolates with restriction endonuclease NotI, followed by PFGE, generated 10 distinct restriction endonuclease analysis patterns consisting of 8 to 13 bands, ranging in size from 78 to 394 kb. PFGE patterns of O1 Inaba strains from the outbreak in Songkhla were identical (P1) except one isolate (P3). The O1 Inaba outbreak strains from Phuket in the same period belonged to P2 pattern, whereas the O1 Ogawa strain from the outbreak in Phuket isolated in 1999 was of P7 pattern. These patterns of O1 Inaba and Ogawa strains were slightly different suggesting that the isolates were epidemiologically related and therefore the outbreaks were likely due to the same V. cholerae clone. Isolates of V. cholerae O1 Inaba from sporadic cases in the neighboring area (eg, Pattani Province) in a similar period of time of the outbreak in Songkhla Province had very similar patterns, with only one single band different from those of the outbreak isolates. This indicates that the Inaba strains isolated from Songkhla Province during the 2001 cholera outbreak belonging to P1 pattern had not spread to other regions in 2001 and 2002. On the otherhand, the sporadic isolates collected from other regions of Thailand were quite distinct from the outbreak isolates in Songkhla Province, especially those from Chaiyaphum and Chaing Mai Provinces, which belonged to P5 and P6 pattern, respectively. Isolates of V. cholerae O139 and non-O1/non-O139 gave different patterns from that of V. cholerae O1. This study shows that the PFGE technique is markedly advantageous in distinguishing strains of V. cholerae isolates leading to insightful detailed charateristics of these isolates in Thailand

The 74-Kilodalton Immunodominant Antigen of the Pathogenic Oomycete Pythium insidiosum Is a Putative Exo-1,3-ß-Glucanase▿

The oomycetous, fungus-like, aquatic organism Pythium insidiosum is the causative agent of pythiosis, a life-threatening infectious disease of humans and animals living in tropical and subtropical areas of the world. Common sites of infection are the arteries, eyes, cutaneous/subcutaneous tissues, and gastrointestinal tract. Diagnosis of pythiosis is time-consuming and difficult. Radical excision of the infected organs is the main treatment for pythiosis because conventional antifungal drugs are ineffective. An immunotherapeutic vaccine prepared from P. insidiosum crude extract showed limited efficacy in the treatment of pythiosis patients. Many pythiosis patients suffer lifelong disabilities or die from an advanced infection. Recently, we identified a 74-kDa major immunodominant antigen of P. insidiosum which could be a target for development of a more effective serodiagnostic test and vaccines. Mass spectrometric analysis identified two peptides of the 74-kDa antigen (s74-1 and s74-2) which perfectly matched a putative exo-1,3-ß-glucanase (EXO1) of Phytophthora infestans. Using degenerate primers derived from these peptides, a 1.1-kb product was produced by PCR, and its sequence was found to be homologous to that of the P. infestans exo-1,3-ß-glucanase gene, EXO1. Enzyme-linked immunosorbent assays targeting the s74-1 and s74-2 synthetic peptides demonstrated that the 74-kDa antigen was highly immunoreactive with pythiosis sera but not with control sera. Phylogenetic analysis using part of the 74-kDa protein-coding sequence divided 22 Thai isolates of P. insidiosum into two clades. Further characterization of the putative P. insidiosum glucanase could lead to new diagnostic tests and to antimicrobial agents and vaccines for the prevention and management of the serious and life-threatening disease of pythiosis