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Biomedical subjects

Richard A Moore

Publications and source records attributed to Richard A Moore.

7 recordsLinked to original sources
PubMed2004

Contribution of gene loss to the pathogenic evolution of Burkholderia pseudomallei and Burkholderia mallei.

Burkholderia pseudomallei is the causative agent of melioidosis. Burkholderia thailandensis is a closely related species that can readily utilize l-arabinose as a sole carbon source, whereas B. pseudomallei cannot. We used Tn5-OT182 mutagenesis to isolate an arabinose-negative mutant of B. thailandensis. Sequence analysis of regions flanking the transposon insertion revealed the presence of an arabinose assimilation operon consisting of nine genes. Analysis of the B. pseudomallei chromosome showed a deletion of the operon from this organism. This deletion was detected in all B. pseudomallei and Burkholderia mallei strains investigated. We cloned the B. thailandensis E264 arabinose assimilation operon and introduced the entire operon into the chromosome of B. pseudomallei 406e via homologous recombination. The resultant strain, B. pseudomallei SZ5028, was able to utilize l-arabinose as a sole carbon source. Strain SZ5028 had a significantly higher 50% lethal dose for Syrian hamsters compared to the parent strain 406e. Microarray analysis revealed that a number of genes in a type III secretion system were down-regulated in strain SZ5028 when cells were grown in l-arabinose, suggesting a regulatory role for l-arabinose or a metabolite of l-arabinose. These results suggest that the ability to metabolize l-arabinose reduces the virulence of B. pseudomallei and that the genes encoding arabinose assimilation may be considered antivirulence genes. The increase in virulence associated with the loss of these genes may have provided a selective advantage for B. pseudomallei as these organisms adapted to survival in animal hosts.

Animals↗
PubMed2003

Therapeutic immunisation with COPV early genes by epithelial DNA delivery.

Following challenge with COPV (canine oral papillomavirus), DNA plasmids encoding COPV L1, E1 or E2 protein were delivered into oral mucosal and cutaneous sites in beagles using particle-mediated immunotherapeutic delivery (PMID). Two weeks post-challenge, a priming dose of 8 microg DNA was delivered followed by a booster dose after a further two weeks. A group of control dogs were vaccinated using plasmid DNA encoding Hepatitis B virus surface (HBVs) gene. All of the control animals developed warts at the vast majority of sites (94%). All of the animals given wild type L1, E1, or E2 developed warts at most sites (88%, 75%, and 88%, respectively). The animals given codon optimised E2 however, were protected from wart growth with only one tiny lesion seen on a single animal that persisted for only a few days. The E1 codon optimised group was also significantly protected with a far lower number of smaller warts (48%) that persisted for a shorter duration. These data suggest that therapeutic immunisation by PMID with papillomavirus early genes is effective and emphasizes the importance of antigen load in the generation of protective responses to papillomavirus proteins.

Animals↗
PubMed2003

Human papillomavirus type 16 E2- and L1-specific serological and T-cell responses in women with vulval intraepithelial neoplasia.

Human papillomavirus type 16 (HPV-16)-associated vulval intraepithelial neoplasia (VIN) is frequently a chronic, multifocal high-grade condition with an appreciable risk of progression to vulval cancer. The requirement to treat women with VIN has recently stimulated the use of immunotherapy with E6/E7 oncogene vaccines. Animal models have shown that E2 may also be a useful vaccine target for HPV-associated disease; however, little is known about E2 immunity in humans. This study investigated the prevalence of HPV-16 E2-specific serological and T-cell responses in 18 women with HPV-16-associated VIN and 17 healthy volunteers. E2 responses were determined by full-length E2-GST ELISA with ELISPOT and proliferation assays using E2 C-terminal protein. As positive controls, HPV-16 L1 responses were measured using virus-like particles (VLPs) and L1-GST ELISA with ELISPOT and proliferation using VLPs as antigen. The VIN patients all showed a strong serological response to L1 compared with the healthy volunteers by VLP (15/18 vs 1/17, P<0.001) and L1-GST ELISA (18/18 vs 1/17, P<0.001). In contrast, L1-specific cellular immune responses were detected in a significant proportion of controls but were more prevalent in the VIN patients by proliferation assay (9/17 vs 17/18, P<0.02) and interferon-gamma ELISPOT (9/17 vs 13/18, P=not significant). Similar and low numbers of patients and controls were seropositive for E2-specific Ig (2/18 vs 1/17). In spite of previous studies showing the immunogenicity of E2 in eliciting primary T-cell responses in vitro, there was a low prevalence of E2 responses in the VIN patients and controls (2/18 vs 0/17).

Adult↗
PubMed2003

Burkholderia pseudomallei class a beta-lactamase mutations that confer selective resistance against ceftazidime or clavulanic acid inhibition.

Burkholderia pseudomallei, the causative agent of melioidosis, is inherently resistant to a variety of antibiotics including aminoglycosides, macrolides, polymyxins, and beta-lactam antibiotics. Despite resistance to many beta-lactams, ceftazidime and beta-lactamase inhibitor-beta-lactam combinations are commonly used for treatment of melioidosis. Here, we examine the enzyme kinetics of beta-lactamase isolated from mutants resistant to ceftazidime and clavulanic acid inhibition and describe specific mutations within conserved motifs of the beta-lactamase enzyme which account for these resistance patterns. Sequence analysis of regions flanking the B. pseudomallei penA gene revealed a putative regulator gene located downstream of penA. We have cloned and sequenced the penA gene from B. mallei and found it to be identical to penA from B. pseudomallei.

3' Flanking Region↗
PubMed2002

Intraepithelial DNA immunisation with a plasmid encoding a codon optimised COPV E1 gene sequence, but not the wild-type gene sequence completely protects against mucosal challenge with infectious COPV in beagles.

DNA plasmids encoding the open reading frames of canine oral papillomavirus (COPV) nonstructural early genes E1, E2, or E7 protein were delivered into both oral mucosal and cutaneous epithelial sites in beagle dogs using particle-mediated immunotherapeutic delivery (PMID) technology. Control dogs were vaccinated with plasmid encoding either hepatitis B virus surface antigen (HBVs) or COPV L1. Using a prophylactic immunisation protocol, a priming dose of plasmid DNA was followed by a booster dose 6 weeks later. Four weeks after boost, all dogs were challenged with infectious COPV particles. Following viral challenge, as shown previously (M. A. Stanley et al., 2001, Vaccine 19, 2783-2792), mucosal papillomas developed in the negative-control HBVs vaccinated dogs, but all animals in the COPV L1 group were fully protected from disease development. In the early gene-vaccinated groups five of six in the E1-vaccinated dogs, two of six in E2-vaccinated dogs, and three of six in the E7-vaccinated beagles developed oral papillomas. Compared to the HBVs negative-control group the oral papillomas that did develop in the early-gene vaccinated beagles were significantly smaller, shorter in duration, and fewer in number. Taken together the disease burden was markedly reduced and this was statistically significant. In a second experiment one group of animals was vaccinated with plasmid encoding the wild-type COPV E1 gene, and a separate group was vaccinated with plasmid encoding a synthetic codon-optimised COPV E1 gene sequence. None of the codon-optimised E1-vaccinated animals developed papillomas at any challenge site. However, all animals vaccinated with wild-type E1 had papillomas. These data suggest that immunisation by PMID with papillomavirus early genes can significantly impact upon subsequent disease development and that full protection can be achieved using improved vectors encoding codon-optimised gene sequences perhaps emphasizing the importance of antigen load in the generation of protective responses to papillomavirus proteins.

Animals↗
PubMed2002

HIV/AIDS in correctional settings: a salient priority for the CDC and HRSA.

Correctional facilities constitute an excellent opportunity to provide treatment, care, and prevention services for a population that may not otherwise access these services. The Centers for Disease Control and Prevention (CDC) and the Health Resources and Services Administration (HRSA) recognize the public health importance of correctional settings and have begun to develop formal strategies to address the HIV/AIDS-relevant needs of incarcerated individuals. The Centers for Disease Control and Prevention and HRSA have implemented policies, activities, and strategic plans to reduce the HIV/AIDS disease burden among the high-risk populations that pass through the nation's prisons and jails. They have also collaborated to address the HIV/AIDS needs of incarcerated populations and have initiated processes for expanding collaboration on these issues to include other federal agencies and prevention partners.

Centers for Disease Control and Prevention, U.S.↗