Search

Piscirickettsia salmonis is an intracellular bacterium that was first isolated and identified in fish cells. Several types of cell lines have been explored for their ability to provide the bacterium with a host cell to replicate in. Tissue culture has been used for growth and cultivation for nearly two decades, until the facultative nature of P. salmonis was confirmed upon the development of blood- and cysteine-based agar. Since then, research has continued to drive the creation of novel agar and broth formulations in order to improve the efficacy of cultivation of P. salmonis. Until now, the techniques and components used for growth have not been thoroughly discussed. In this review, the methods and formulations for growth of P. salmonis in tissue culture and cell-free media will be examined. [ABSTRACT FROM AUTHOR]

Increased use of antiviral monoclonal antibodies (mAbs) for treatment and prophylaxis necessitates better understanding of their impact on endogenous immunity to vaccines and viruses. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic presented an opportunity to study immunity in individuals who received antiviral mAbs and were subsequently immunized with vaccines encoding the mAb-targeted viral spike antigen. Here, we describe the impact of administration of an antibody combination, casirivimab plus imdevimab (CAS+IMD), on immune responses to subsequent SARS-CoV-2 vaccination in humans, nonhuman primates, and mice. The presence of CAS+IMD at the time of vaccination led to a specific diminishment of vaccine-elicited pseudovirus neutralizing antibody titers without overall dampening of spike protein-directed immune responses, including antibody, B cell, and T cell responses. The impact on pseudovirus neutralizing titers extended to other therapeutic anti-spike protein antibodies when used as either monotherapy or combination therapy. The specific reduction in pseudovirus neutralizing titers was the result of epitope masking, a phenomenon where specific epitopes are bound by high-affinity antibodies and blocked from B cell recognition. Encouragingly, this reduction in pseudovirus neutralizing titers was reversible with additional booster vaccination. Moreover, by assessing the antiviral immune response in SARS-CoV-2-infected individuals treated therapeutically with CAS+IMD, we demonstrated alteration of antiviral humoral immunity in those who had received mAb therapy, but only in those individuals who had yet to start mounting their natural immune response at the time of mAb treatment. Together, these data demonstrate that antiviral mAbs can alter endogenous humoral immunity during vaccination or infection.

mRNA-1647 is an investigational mRNA-based vaccine against cytomegalovirus (CMV) that contains sequences encoding the CMV proteins glycoprotein B and pentamer. Humoral and cellular immune responses were evaluated in blood samples collected from healthy CMV-seropositive and CMV-seronegative adults who participated in a phase 1 trial of a three-dose series of mRNA-1647 (NCT03382405). Neutralizing antibody (nAb) titers against fibroblast and epithelial cell infection in sera from CMV-seronegative mRNA-1647 recipients were higher than those in sera from control CMV-seropositive samples and remained elevated up to 12 months after dose 3. nAb responses elicited by mRNA-1647 were comparable across 14 human CMV (HCMV) strains. Frequencies of antigen-specific memory B cells increased in CMV-seropositive and CMV-seronegative participants after each mRNA-1647 dose and remained elevated for up to 6 months after dose 3. mRNA-1647 elicited robust increases in frequencies and polyfunctionality of CD4 + T helper type 1 and effector CD8 + T cells in samples from CMV-seronegative and CMV-seropositive participants after stimulation with HCMV-specific peptides. The administration of three doses of mRNA-1647 to healthy adults elicited high nAb titers with wide-breadth, long-lasting memory B cells, and strong polyfunctional T-cell responses. These findings support further clinical development of the mRNA-1647 vaccine against CMV.IMPORTANCECytomegalovirus (CMV), a common virus that can infect people of all ages, may lead to serious health problems in unborn babies and those with a weakened immune system. Currently, there is no approved vaccine available to prevent CMV infection; however, the investigational messenger RNA (mRNA)-based CMV vaccine, mRNA-1647, is undergoing evaluation in clinical trials. The current analysis examined samples from a phase 1 trial of mRNA-1647 in healthy adults to better understand how the immune system reacts to vaccination. Three doses of mRNA-1647 produced a long-lasting immune response, thus supporting further investigation of the vaccine in the prevention of CMV infection.CLINICAL TRIALSRegistered at ClinicalTrials.gov (NCT03382405)., Competing Interests: All authors are employees of Moderna, Inc., and may hold stock/stock options in the company.

Despite the remarkable success of SARS-CoV-2 vaccines, the rise of variants, some of which are more resistant to the effects of vaccination, highlights the potential need for additional COVID-19 vaccines. We used the Multiple Antigen-Presenting System (MAPS) technology, in which proteins are presented on a polysaccharide polymer to induce antibody, Th1, Th17 and CD8+ T cell responses, to engineer a novel vaccine targeting SARS-CoV-2. This vaccine contains a fragment of the spike (S) protein receptor-binding domain (RBD) sequence of the original D614G strain and was used to immunize nonhuman primates (NHP) for assessment of immunological responses and protection against SARS-CoV-2 challenge. The SARS-CoV-2 MAPS vaccine generated robust neutralizing antibodies as well as Th1, Th17 and cytotoxic CD8 T-cell responses in NHPs. Furthermore, MAPS-immunized NHPs had significantly lower viral loads in the nasopharynx and lung compared to control animals. Taken together, these findings support the use of the MAPS platform to make a SARS-CoV-2 vaccine. The nature of the platform also could enable its use for the inclusion of different variants in a single vaccine.