The spatio-temporal distribution of acute encephalitis syndrome and its association with climate and landcover in Vietnam

BACKGROUND

Acute encephalitis syndrome (AES) differs in its spatio-temporal distribution in Vietnam with the highest incidence seen during the summer months in the northern provinces. AES has multiple aetiologies, and the cause remains unknown in many cases. While vector-borne disease such as Japanese encephalitis and dengue virus and non-vector-borne diseases such as influenza and enterovirus show evidence of seasonality, associations with climate variables and the spatio-temporal distribution in Vietnam differs between these. The aim of this study was therefore to understand the spatio-temporal distribution of, and risk factors for AES in Vietnam to help hypothesise the aetiology.

METHODS

The number of monthly cases per province for AES, meningitis and diseases including dengue fever; influenza-like-illness (ILI); hand, foot, and mouth disease (HFMD); and Streptococcus suis were obtained from the General Department for Preventive Medicine (GDPM) from 1998-2016. Covariates including climate, normalized difference vegetation index (NDVI), elevation, the number of pigs, socio-demographics, JEV vaccination coverage and the number of hospitals were also collected. Spatio-temporal multivariable mixed-effects negative binomial Bayesian models with an outcome of the number of cases of AES, a combination of the covariates and harmonic terms to determine the magnitude of seasonality were developed.

RESULTS

The national monthly incidence of AES declined by 63.3% over the study period. However, incidence increased in some provinces, particularly in the Northwest region. In northern Vietnam, the incidence peaked in the summer months in contrast to the southern provinces where incidence remained relatively constant throughout the year. The incidence of meningitis, ILI and S. suis infection; temperature, relative humidity with no lag, NDVI at a lag of one month, and the number of pigs per 100,000 population were positively associated with the number of cases of AES in all models in which these covariates were included.

CONCLUSIONS

The positive correlation of AES with temperature and humidity suggest that a number of cases may be due to vector-borne diseases, suggesting a need to focus on vaccination campaigns. However, further surveillance and research are recommended to investigate other possible aetiologies such as S. suis or Orientia tsutsugamushi.

Spatiotemporal Patterns of Anthrax, Vietnam, 1990–2015

Anthrax is a priority zoonosis for control in Vietnam. The geographic distribution of anthrax remains to be defined, challenging our ability to target areas for control. We analyzed human anthrax cases in Vietnam to obtain anthrax incidence at the national and provincial level. Nationally, the trendline for cases remained at ≈61 cases/year throughout the 26 years of available data, indicating control efforts are not effectively reducing disease burden over time. Most anthrax cases occurred in the Northern Midlands and Mountainous regions, and the provinces of Lai Chau, Dien Bien, Lao Cai, Ha Giang, Cao Bang, and Son La experienced some of the highest incidence rates. Based on spatial Bayes smoothed maps, every region of Vietnam experienced human anthrax cases during the study period. Clarifying the distribution of anthrax in Vietnam will enable us to better identify risk areas for improved surveillance, rapid clinical care, and livestock vaccination campaigns.

CDX2 promotes anchorage-independent growth by transcriptional repression of IGFBP-3

CDX2 is a Drosophila caudal-related homeobox transcription factor that is important for the establishment and maintenance of intestinal epithelial cells. We have reported that CDX2 promotes tumorigenicity in a subset of human colorectal cancer cell lines. Here, we present evidence that CDX2 negatively regulates the well-documented growth inhibitor insulin-like growth factor binding protein-3 (IGFBP-3). Specifically, CDX2 binds to the IGFBP-3 gene promoter and can repress IGFBP-3 transcription, protein expression and secretion. Furthermore, inhibition of IGFBP-3 partially rescues the decreased anchorage-independent growth phenotype observed in CDX2 knockout cells. These data demonstrate for the first time that (1) CDX2 can function as a transcriptional repressor, and (2) one mechanism by which CDX2 promotes anchorage-independent growth is by transcriptional repression of IGFBP-3.

CDX2 does not suppress tumorigenicity in the human gastric cancer cell line MKN45

CDX2 is a Drosophila caudal-related homeobox transcription factor that is expressed specifically in the intestine. In mice, ectopic expression of CDX2 in the gastric mucosa gives rise to intestinal metaplasia and in one model, gastric carcinoma. In humans, increased CDX2 expression is associated with gastric intestinal metaplasia and tubular adenocarcinomas. These patterns of expression have shown that CDX2 is important for the initiation of intestinal metaplasia in the gastric mucosa, but the role of CDX2 in established gastric cancer remains unclear. We sought to determine whether CDX2 contributes to tumorigenic potential in established gastric cancer. The CDX2 gene in MKN45 gastric carcinoma cells was disrupted using targeted homologous recombination. The resulting CDX2-/- cells are essentially identical to their parental cells, with the exception of CDX2 ablation. We found no significant differences in the proliferation of CDX2-/- cells compared to CDX2+/+ cells, in vitro or in vivo. Molecular analyses show that loss of CDX2 predominantly altered the expression of genes involved in intestinal glandular differentiation and adhesion. However, there were no microscopic differences in tumor differentiation. We conclude that disruption of CDX2 in MKN45 cells does not significantly affect their tumorigenic potential.

CDX2 has tumorigenic potential in the human colon cancer cell lines LOVO and SW48

CDX2 is a Drosophila caudal-related homeobox transcription factor that is important for the establishment and maintenance of intestinal epithelial cells. CDX2 is a marker of colon cancer, with strong staining in up to 90% of colonic adenocarcinomas. CDX2 heterozygous-null mice develop colonic neoplasms, which have suggested that CDX2 is a tumor suppressor. However, CDX2 has not been reported to affect xenograft growth. Furthermore, CDX2 is rarely mutated in colon cancer, which has led to suggestions that it may play only a minor role as a tumor suppressor in colon cancer. To understand the functional contributions of CDX2 to colon cancer, we disrupted CDX2 in LOVO and SW48 human colon cancer cell lines by targeted homologous recombination. Consistent with the literature, disruption of CDX2 enhanced anchorage-dependent cell proliferation. However, homozygous loss of CDX2 led to significant inhibition of anchorage-independent growth in LOVO cells, and cell lethality in SW48 cells. Further analyses revealed that disruption of CDX2 led to anchorage-independent G1 to S growth arrest and anoikis. In vivo xenograft studies confirmed that disruption of CDX2 inhibited LOVO tumor growth. These data demonstrate that CDX2 mediates anchorage-independent growth and survival. Thus, CDX2 has tumorigenic potential in the human colon cancer cell lines LOVO and SW48.

Combination bacteriolytic therapy for the treatment of experimental tumors

Current chemotherapeutic approaches for cancer are in part limited by the inability of drugs to destroy neoplastic cells within poorly vascularized compartments of tumors. We have here systematically assessed anaerobic bacteria for their capacity to grow expansively within avascular compartments of transplanted tumors. Among 26 different strains tested, one (Clostridium novyi) appeared particularly promising. We created a strain of C. novyi devoid of its lethal toxin (C. novyi-NT) and showed that intravenously injected C. novyi-NT spores germinated within the avascular regions of tumors in mice and destroyed surrounding viable tumor cells. When C. novyi-NT spores were administered together with conventional chemotherapeutic drugs, extensive hemorrhagic necrosis of tumors often developed within 24 h, resulting in significant and prolonged antitumor effects. This strategy, called combination bacteriolytic therapy (COBALT), has the potential to add a new dimension to the treatment of cancer.

A mutant antigen-presenting cell defective in antigen presentation expresses class II MHC molecules with an altered conformation

Ag presentation by APC to class II MHC-restricted T cells involves a sequence of events: 1) intracellular processing of protein Ag into immunogenic peptides, 2) specific binding of peptides to class II MHC molecules, and then 3) transport of the MHC-peptide complexes to the plasma membrane. The critical event in the activation of T cells by APC is the recognition of MHC-associated antigenic determinants by the TCR/CD3 complex. In this report we describe the isolation and characterization of a mutant APC with a defect in an intracellular process that results in its inability to form MHC-peptide complexes for recognition by T cells. The mutant APC cannot present many different protein Ag with both I-A and I-E molecules but is able to present processing-independent peptides. The functional defect in the mutant APC is not caused by either a decrease in expression or a structural mutation in class II MHC molecules. Further, there is no mutation in the invariant chain (li) and it displays a normal kinetics of association and dissociation from the class II MHC molecules during biosynthesis. Although the mutation is not in the genes encoding for the class II MHC molecules or li, the mutant APC expresses class II MHC molecules with distinct serological epitopes suggestive of an altered conformation. Pulse-chase experiments suggest that a conformational difference between I-Ad molecules of wild-type and mutant cells occurs after the class II molecules exit from the endoplasmic reticulum but while they are still associated with li. The mutant cell produces few compact (SDS-resistant) class II heterodimers. This mutant APC provides a tool for studying the cell biology of Ag processing and presentation.

A mutant antigen-presenting cell defective in antigen presentation expresses class II MHC molecules with an altered conformation

Ag presentation by APC to class II MHC-restricted T cells involves a sequence of events: 1) intracellular processing of protein Ag into immunogenic peptides, 2) specific binding of peptides to class II MHC molecules, and then 3) transport of the MHC-peptide complexes to the plasma membrane. The critical event in the activation of T cells by APC is the recognition of MHC-associated antigenic determinants by the TCR/CD3 complex. In this report we describe the isolation and characterization of a mutant APC with a defect in an intracellular process that results in its inability to form MHC-peptide complexes for recognition by T cells. The mutant APC cannot present many different protein Ag with both I-A and I-E molecules but is able to present processing-independent peptides. The functional defect in the mutant APC is not caused by either a decrease in expression or a structural mutation in class II MHC molecules. Further, there is no mutation in the invariant chain (li) and it displays a normal kinetics of association and dissociation from the class II MHC molecules during biosynthesis. Although the mutation is not in the genes encoding for the class II MHC molecules or li, the mutant APC expresses class II MHC molecules with distinct serological epitopes suggestive of an altered conformation. Pulse-chase experiments suggest that a conformational difference between I-Ad molecules of wild-type and mutant cells occurs after the class II molecules exit from the endoplasmic reticulum but while they are still associated with li. The mutant cell produces few compact (SDS-resistant) class II heterodimers. This mutant APC provides a tool for studying the cell biology of Ag processing and presentation.

Stimulation of B lymphocytes through surface Ig receptors induces LFA-1 and ICAM-1-dependent adhesion

Engagement of the surface Ig receptor with anti-IgM antibodies stimulates murine B lymphocytes to markedly increase their expression of the cell adhesion molecules ICAM-1 and LFA-1. Stimulated B cells display increased homotypic adhesiveness and form spontaneous heterotypic conjugates with T lymphocytes. This latter T-B cell interaction is further enhanced if T cells have been previously activated with phorbol esters. In all cases, the formation of cell-cell conjugates is dependent on LFA-1-ICAM-1-mediated interactions as assessed in mAb blocking experiments. B lymphocytes stimulated with anti-IgM display a marked increase in binding to ICAM-1-transfected L cells. This cell-cell interaction is inhibited by anti-LFA-1 mAb binding to the B lymphocyte. Together, these results demonstrate that there is an induction of both ICAM-1 and LFA-1 on stimulated B cells and a corresponding increase in the adhesiveness of these cells. These findings suggest that Ag binding to the surface Ig receptor could prepare a B lymphocyte for subsequent interaction with a T lymphocyte. This provides insight into how efficient T-B collaboration may occur between very infrequent Ag-specific lymphocytes.

Stimulation of B lymphocytes through surface Ig receptors induces LFA-1 and ICAM-1-dependent adhesion

Engagement of the surface Ig receptor with anti-IgM antibodies stimulates murine B lymphocytes to markedly increase their expression of the cell adhesion molecules ICAM-1 and LFA-1. Stimulated B cells display increased homotypic adhesiveness and form spontaneous heterotypic conjugates with T lymphocytes. This latter T-B cell interaction is further enhanced if T cells have been previously activated with phorbol esters. In all cases, the formation of cell-cell conjugates is dependent on LFA-1-ICAM-1-mediated interactions as assessed in mAb blocking experiments. B lymphocytes stimulated with anti-IgM display a marked increase in binding to ICAM-1-transfected L cells. This cell-cell interaction is inhibited by anti-LFA-1 mAb binding to the B lymphocyte. Together, these results demonstrate that there is an induction of both ICAM-1 and LFA-1 on stimulated B cells and a corresponding increase in the adhesiveness of these cells. These findings suggest that Ag binding to the surface Ig receptor could prepare a B lymphocyte for subsequent interaction with a T lymphocyte. This provides insight into how efficient T-B collaboration may occur between very infrequent Ag-specific lymphocytes.

Role of ICAM-1 in antigen presentation demonstrated by ICAM-1 defective mutants

We report a methodology for selecting APC with mutations that have impaired their ability to present Ag to T cells. A20 B lymphoblastoid cells were mutagenized and then repeatedly cocultured with murine T-T hybridomas in the presence of specific Ag. During these cocultures, the T-T hybridomas kill the competent APC, allowing the outgrowth of inactive variants. Two variants, A20.M1 and A20.M2, were isolated and studied in detail. These variants are impaired in their ability to present multiple Ag to T cells. This defect is also observed for the presentation of processing independent peptides by fixed APC indicating that a lesion exists in a post-Ag processing step. The level of expression of MHC molecules is unaffected and the functional defect in the APC is not localized to a particular MHC molecule. In contrast, these mutants were found to have a selective decrease in the expression of the murine homolog of ICAM-1, and the residual ability of these cells to present Ag was not blocked by anti-ICAM-1 mAb. Conversely, Ag presentation by the wild-type A20 is inhibited by anti-ICAM-1 mAb. Similarly, anti-LFA-1 mAb inhibited the response of T cells to Ag presented by the wild-type A20 to a much greater degree than by the mutant cells, indicating that LFA-1 is involved in interaction of T cells with the former, but not latter, APC. In the apparent absence of a contribution of LFA-1 to the T cell-APC interaction, either as a result of mAb blocking or the disruption of the APC membrane, the mutant and wild-type APC have a similar level of Ag-presenting activity. Reconstitution of ICAM-1 expression in these mutants by transfection with murine ICAM-1 cDNA fully restores their ability to present Ag. Together these results demonstrate that a murine ICAM-1 homolog is expressed on A20 B cells, where it functions as a major cell interaction molecule. The degree of functional impairment in these mutant APC gives insight into the contribution of cell interaction molecules to efficient Ag presentation and T cell-B cell interaction. Finally, these results also demonstrate the feasibility of selecting APC with mutations affecting Ag presentation.

Role of ICAM-1 in antigen presentation demonstrated by ICAM-1 defective mutants

We report a methodology for selecting APC with mutations that have impaired their ability to present Ag to T cells. A20 B lymphoblastoid cells were mutagenized and then repeatedly cocultured with murine T-T hybridomas in the presence of specific Ag. During these cocultures, the T-T hybridomas kill the competent APC, allowing the outgrowth of inactive variants. Two variants, A20.M1 and A20.M2, were isolated and studied in detail. These variants are impaired in their ability to present multiple Ag to T cells. This defect is also observed for the presentation of processing independent peptides by fixed APC indicating that a lesion exists in a post-Ag processing step. The level of expression of MHC molecules is unaffected and the functional defect in the APC is not localized to a particular MHC molecule. In contrast, these mutants were found to have a selective decrease in the expression of the murine homolog of ICAM-1, and the residual ability of these cells to present Ag was not blocked by anti-ICAM-1 mAb. Conversely, Ag presentation by the wild-type A20 is inhibited by anti-ICAM-1 mAb. Similarly, anti-LFA-1 mAb inhibited the response of T cells to Ag presented by the wild-type A20 to a much greater degree than by the mutant cells, indicating that LFA-1 is involved in interaction of T cells with the former, but not latter, APC. In the apparent absence of a contribution of LFA-1 to the T cell-APC interaction, either as a result of mAb blocking or the disruption of the APC membrane, the mutant and wild-type APC have a similar level of Ag-presenting activity. Reconstitution of ICAM-1 expression in these mutants by transfection with murine ICAM-1 cDNA fully restores their ability to present Ag. Together these results demonstrate that a murine ICAM-1 homolog is expressed on A20 B cells, where it functions as a major cell interaction molecule. The degree of functional impairment in these mutant APC gives insight into the contribution of cell interaction molecules to efficient Ag presentation and T cell-B cell interaction. Finally, these results also demonstrate the feasibility of selecting APC with mutations affecting Ag presentation.

A physical map of the sorghum chloroplast genome

The chloroplast genome of the IS1112C cytoplasm of sorghum was mapped by the construction of a Bam-HI library in pUC8, and hybridization with BamHI, SalI, and PstI digests of chloroplast DNA (ctDNA) of sorghum and maize. The molecules are extensively colinear, with only one of 13 SalI fragments differing slightly from maize. Seven of 70 restriction sites differed in the two species. A total molecular size of ca. 138 kb was estimated for sorghum. The inverted repeat was not conserved between sorghum and maize, as revealed by a slightly larger BamHI 16S rDNA fragment in sorghum. Homology of a sequence adjacent to the γbcl gene and one end of the inverted repeat was detected. These homologies were also observed in maize, and suggest that the ctDNA genomes of sorghum and maize share small reiterations of sequences of the inverted repeat.