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Biomedical subjects

Adam Penn-Nicholson

Publications and source records attributed to Adam Penn-Nicholson.

4 recordsLinked to original sources

Future-proofing tuberculosis therapy: framework for concurrent drug and resistance testing development.

The rapid emergence of resistance to novel tuberculosis drugs, such as bedaquiline, is a key threat to the long-term effectiveness of novel regimens. Given that the introduction of these agents has enabled the introduction of an all-oral regimen for rifampicin-resistant and multidrug-resistant tuberculosis, the rise of resistance underscores the urgent need to safeguard their efficacy and responsible use. A major barrier is the delay in developing reliable tools to detect resistance to novel compounds, which limits clinical decision-making and surveillance efforts. Herein, we outline a framework for integrating the development of drug susceptibility testing alongside tuberculosis drug development, including early stage resistance profiling and defining appropriate epidemiological cutoff values. We highlight key gaps, including the need for structured partnerships between drug developers, diagnostic manufacturers, regulators, research institutions, funders, and policy makers. We propose a roadmap to accelerate drug susceptibility testing and development of new tuberculosis regimens, ensuring that resistance detection maintains pace with the introduction of novel drugs. Establishing collaborative platforms for data sharing, genomic analysis, and diagnostic innovation will help ensure that resistance detection evolves in step with drug development, thereby preserving novel treatments and improving global tuberculosis care.

Humans↗

Biology of CCR5 and its role in HIV infection and treatment.

Chemokine receptors are found on cell surfaces and promote cellular migration by chemotaxis. The CC chemokine receptor 5 (CCR5) is used by the human immunodeficiency virus (HIV) to infect cells. Strategies that target human CCR5 are therefore being developed to prevent and treat HIV infection. Antiviral strategies that target a host element necessary for viral replication may be predicted to interfere with the function of that element and may therefore adversely affect the host. We conducted a review of the literature between November 2005 and April 2006 with a focus on articles addressing the genetics and function of CCR5, the effects of CCR5 deletion in human and murine systems, and treatment strategies for HIV infection that target this coreceptor. English-language articles in the human and murine literature published between March 1996 and April 2006 were identified through a search of MEDLINE using CCR5 as the search term. Relevant articles as judged by their titles and abstracts were reviewed in detail. In addition, based on our knowledge of the field and with permission, unpublished work was also reviewed. In this article, we explore the effects that targeting CCR5 may have on host defenses in individuals with immunity already compromised by HIV infection.

Animals↗

Identification of critical determinants on ACE2 for SARS-CoV entry and development of a potent entry inhibitor.

Severe acute respiratory syndrome (SARS) is caused by a novel coronavirus, SARS-CoV. Virus entry into cells is mediated through interactions between spike (S) glycoprotein and angiotensin-converting enzyme 2 (ACE2). Alanine scanning mutagenesis analysis was performed to identify determinants on ACE2 critical for SARS-CoV infection. Results indicated that charged amino acids between residues 22 and 57 were important, K26 and D30, in particular. Peptides representing various regions of ACE2 critical for virus infection were chemically synthesized and evaluated for antiviral activity. Two peptides (a.a. 22-44 and 22-57) exhibited a modest antiviral activity with IC50 of about 50 microM and 6 microM, respectively. One peptide comprised of two discontinuous segments of ACE2 (a.a. 22-44 and 351-357) artificially linked together by glycine, exhibited a potent antiviral activity with IC50 of about 0.1 microM. This novel peptide is a promising candidate as a therapeutic agent against this deadly emerging pathogen.

Amino Acid Sequence↗

Comparing the ex vivo fitness of CCR5-tropic human immunodeficiency virus type 1 isolates of subtypes B and C.

Continual human immunodeficiency virus type 1 (HIV-1) evolution and expansion within the human population have led to unequal distribution of HIV-1 group M subtypes. In particular, recent outgrowth of subtype C in southern Africa, India, and China has fueled speculation that subtype C isolates may be more fit in vivo. In this study, nine subtype B and six subtype C HIV-1 isolates were added to peripheral blood mononuclear cell cultures for a complete pairwise competition experiment. All subtype C HIV-1 isolates were less fit than subtype B isolates (P < 0.0001), but intrasubtype variations in HIV-1 fitness were not significant. Increased fitness of subtype B over subtype C was also observed in primary CD4(+) T cells and macrophages from different human donors but not in skin-derived human Langerhans cells. Detailed analysis of the retroviral life cycle during several B and C virus competitions indicated that the efficiency of host cell entry may have a significant impact on relative fitness. Furthermore, phyletic analyses of fitness differences suggested that, for a recombined subtype B/C HIV-1 isolate, higher fitness mapped to the subtype B env gene rather than the subtype C gag and pol genes. These results suggest that subtype B and C HIV-1 may be transmitted with equal efficiency (Langerhans cell data) but that subtype C isolates may be less fit following initial infection (T-cell and macrophage data) and may lead to slower disease progression.

Cells, Cultured↗