Local and Systemic Immunity During Five Vaccinations Against SARS-CoV-2 in Zanubrutinib-Treated Patients With Chronic Lymphocytic Leukemia.

Background: Patients with chronic lymphocytic leukemia (CLL) are vulnerable to coronavirus disease 2019 (COVID-19) and are at risk of inferior response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination, especially if treated with the first-generation Bruton's tyrosine kinase inhibitor (BTKi) ibrutinib. We aimed to evaluate the impact of the third-generation BTKi, zanubrutinib, on systemic and mucosal response to SARS-CoV-2 vaccination. Methods: Nine patients with CLL with ongoing zanubrutinib therapy were included and donated blood and saliva during SARS-CoV-2 vaccination, before vaccine doses 3 and 5 and 2 - 3 weeks after doses 3, 4, and 5. Ibrutinib-treated control patients (n = 7) and healthy aged-matched controls (n = 7) gave blood 2 - 3 weeks after vaccine dose 5. We quantified reactivity and neutralization capacity of SARS-CoV-2-specific IgG and IgA antibodies (Abs) in both serum and saliva, and reactivity of T cells activated with viral peptides. Results: Both zanubrutinib- and ibrutinib-treated patients had significantly, up to 1,000-fold, lower total spike-specific Ab levels after dose 5 compared to healthy controls (P < 0.01). Spike-IgG levels in serum from zanubrutinib-treated patients correlated well to neutralization capacity (r = 0.68; P < 0.0001) and were thus functional. Mucosal immunity (specific IgA in serum and saliva) was practically absent in zanubrutinib-treated patients even after five vaccine doses, whereas healthy controls had significantly higher levels (tested in serum after vaccine dose 5) (P < 0.05). In contrast, T-cell reactivity against SARS-CoV-2 peptides was equally high in zanubrutinib- and ibrutinib-treated patients as in healthy control donors. Conclusions: In our small cohort of zanubrutinib-treated CLL patients, we conclude that up to five doses of SARS-CoV-2 vaccination induced no detectable IgA mucosal immunity, which likely will impair the primary barrier defence against the infection. Systemic IgG responses were also impaired, whereas T-cell responses were normal. Further and larger studies are needed to evaluate the impact of these findings on disease protection.

Candidate Phyla Radiation, an Underappreciated Division of the Human Microbiome, and Its Impact on Health and Disease.

Candidate phyla radiation (CPR) is an emerging division of the bacterial domain within the human microbiota. Still poorly known, these microorganisms were first described in the environment in 1981 as "ultramicrobacteria" with a cell volume under 0.1 µm3 and were first associated with the human oral microbiota in 2007. The evolution of technology has been paramount for the study of CPR within the human microbiota. In fact, since these ultramicrobacteria have yet to be axenically cultured despite ongoing efforts, progress in imaging technology has allowed their observation and morphological description. Although their genomic abilities and taxonomy are still being studied, great strides have been made regarding their taxonomic classification, as well as their lifestyle. In addition, advancements in next-generation sequencing and the continued development of bioinformatics tools have allowed their detection as commensals in different human habitats, including the oral cavity and gastrointestinal and genital tracts, thus highlighting CPR as a nonnegligible part of the human microbiota with an impact on physiological settings. Conversely, several pathologies present dysbiosis affecting CPR levels, including inflammatory, mucosal, and infectious diseases. In this exhaustive review of the literature, we provide a historical perspective on the study of CPR, an overview of the methods available to study these organisms and a description of their taxonomy and lifestyle. In addition, their distribution in the human microbiome is presented in both homeostatic and dysbiotic settings. Future efforts should focus on developing cocultures and, if possible, axenic cultures to obtain isolates and therefore genomes that would provide a better understanding of these ultramicrobacteria, the importance of which in the human microbiome is undeniable.

State of the Art in the Culture of the Human Microbiota: New Interests and Strategies.

The last 5 years have seen a turning point in the study of the gut microbiota with a rebirth of culture-dependent approaches to study the gut microbiota. High-throughput methods have been developed to study bacterial diversity with culture conditions aimed at mimicking the gut environment by using rich media such as YCFA (yeast extract, casein hydrolysate, fatty acids) and Gifu anaerobic medium in an anaerobic workstation, as well as media enriched with rumen and blood and coculture, to mimic the symbiosis of the gut microbiota. Other culture conditions target phenotypic and metabolic features of bacterial species to facilitate their isolation. Preexisting technologies such as next-generation sequencing and flow cytometry have also been utilized to develop innovative methods to isolate previously uncultured bacteria or explore viability in samples of interest. These techniques have been applied to isolate CPR (Candidate Phyla Radiation) among other, more classic approaches. Methanogenic archaeal and fungal cultures present different challenges than bacterial cultures. Efforts to improve the available systems to grow archaea have been successful through coculture systems. For fungi that are more easily isolated from the human microbiota, the challenge resides in the identification of the isolates, which has been approached by applying matrix-assisted laser desorption ionization-time of flight mass spectrometry technology to fungi. Bacteriotherapy represents a nonnegligible avenue in the future of medicine to correct dysbiosis and improve health or response to therapy. Although great strides have been achieved in the last 5 years, efforts in bacterial culture need to be sustained to continue deciphering the dark matter of metagenomics, particularly CPR, and extend these methods to archaea and fungi.