Mycobacterium abscessus (M. abscessus) is an opportunistic pathogen usually colonizing abnormal lung airways and is often seen in patients with cystic fibrosis. Currently, there is no vaccine available for M. abscessus in clinical development. The treatment of M. abscessus-related pulmonary diseases is peculiar due to intrinsic resistance to several commonly used antibiotics. The development of either prophylactic or therapeutic interventions for M. abscessus pulmonary infections is hindered by the absence of an adequate experimental animal model. In this review, we outline the critical elements related to M. abscessus virulence mechanisms, host–pathogen interactions, and treatment challenges associated with M. abscessus pulmonary infections. The challenges of effectively combating this pathogen include developing appropriate preclinical animal models of infection, developing proper diagnostics, and designing novel strategies for treating drug-resistant M. abscessus.

Mycobacterium bovis is responsible for bovine tuberculosis in both animals and humans. Despite being one of the most important global zoonotic disease, data related to the ecology and pathogenicity of bovine tuberculosis is scarce, especially in developing countries. In this report, we examined the dynamics of M. bovis transmission among dairy cattle in the Nile Delta of Egypt. Animals belonging to 27 herds from 7 governorates were tested by the Single Intradermal Comparative Skin Tuberculin (SICST), as a preliminary screen for the presence of bovine tuberculosis. Positive SICST reactors were identified in 3% of the animals spread among 40% of the examined herds. Post-mortem examination of slaughtered reactors confirmed the presence of both pulmonary and/or digestive forms of tuberculosis in > 50% of the examined animals. Targeted and whole-genome analysis of M. bovis isolates indicated the emergences of a predominant spoligotype (SB0268) between 2013–2015, suggesting a recent clonal spread of this isolate within the Nile Delta. Surprisingly, 2 isolates belonged to M. bovis BCG group, which are not allowed for animal vaccination in Egypt, while the rest of isolates belonged to the virulent M. bovis clonal complex European 2 present in Latin America and several European countries. Analysis of strain virulence in the murine model of tuberculosis indicated the emergence of a more virulent strain (MBE4) with a specific genotype. More analysis is needed to understand the molecular basis for successful spread of virulent isolates of bovine tuberculosis among animals and to establish genotype/phenotype association.

Bovine tuberculosis, caused byMycobacterium tuberculosisvar.bovis(M. bovis), is an important enzootic disease affecting mainly cattle, worldwide. Despite the implementation of national campaigns to eliminate the disease, bovine tuberculosis remains recalcitrant to eradication in several countries.

The recent pandemic caused by the SARS-CoV-2 virus continues to be an enormous global challenge faced by the healthcare sector. Availability of new vaccines and drugs targeting SARS-CoV-2 and sequelae of COVID-19 has given the world hope in ending the pandemic. However, the emergence of mutations in the SARS-CoV-2 viral genome every couple of months in different parts of world is a persistent danger to public health. Currently there is no single treatment to eradicate the risk of COVID-19. The widespread transmission of SARS-CoV-2 due to the Omicron variant necessitates continued work on the development and implementation of effective vaccines. Moreover, there is evidence that mutations in the receptor domain of the SARS-CoV-2 spike glycoprotein led to the decrease in current vaccine efficacy by escaping antibody recognition. Therefore, it is essential to actively identify the mechanisms by which SARS-CoV-2 evades the host immune system, study the long-lasting effects of COVID-19 and develop therapeutics targeting SARS-CoV-2 infections in humans and preclinical models. In this review, we describe the pathogenic mechanisms of SARS-CoV-2 infection as well as the innate and adaptive host immune responses to infection. We address the ongoing need to develop effective vaccines that provide protection against different variants of SARS-CoV-2, as well as validated endpoint assays to evaluate the immunogenicity of vaccines in the pipeline, medications, anti-viral drug therapies and public health measures, that will be required to successfully end the COVID-19 pandemic.

Tuberculosis (TB) killed approximately 1.3 million people in 2022 and remains a leading cause of death from the bacteria Mycobacterium tuberculosis (M.tb); this number of deaths was surpassed only by COVID-19, caused by the SARS-CoV-2 virus. The alarming emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) M.tb strains presents an urgent need for effective new treatments. Our study aimed to determine the synergistic effects of antibiotic combinations against M.tb. Using a high-throughput in vitro checkerboard assay, we evaluated the interactions of Bedaquiline (BDQ) and other antibiotics including Capreomycin (CAP), Linezolid (LIN), and Sutezolid (SUT) against M.tb H37Rv. BDQ and CAP demonstrated in vitro enhanced effect, which prompted further investigation in vivo using the murine low dose aerosol (LDA) model. After aerosol challenge with M.tb, C57BL/6 mice were treated with BDQ, CAP, or their combination, starting 28 days post-infection. The antimicrobial treatment lasted four weeks, and the bacterial burden in lung and spleen tissues was assessed at the end of treatment. At 4 weeks post-treatment, a significant reduction in bacterial load was observed within the lungs and spleens of mice given BDQ alone or given as a BDQ/CAP combination compared to the untreated group. In contrast, CAP monotherapy led to an increase in bacterial load within the lung and no significant difference in bacterial burden in the spleen in comparison to the untreated mice. These results were confirmed in the guinea pig model of TB, where both BDQ and the BDQ/CAP combination treatment led to a decrease in bacterial burden in the lung and spleen, whereas CAP had no significant effect on bacterial burden at the 4-week post treatment timepoint. We next determined whether there may be differences in vitro with the BDQ/CAP combination against M.tb lineages 1, 2 and 4. We determined that in vitro enhanced effect was not observed in some representative strains of M.tb lineage 4, indicating variability in drug effectiveness across M.tb lineages. This research underscores the complexity of TB treatment and the critical need for innovative approaches to combat this global health threat.