We describe 9 patients at a medical center in Detroit, Michigan, USA, with severe acute respiratory syndrome coronavirus 2 and Clostridioides difficile . Both infections can manifest as digestive symptoms and merit screening when assessing patients with diarrhea during the coronavirus disease pandemic. These co-infections also highlight the continued importance of antimicrobial stewardship.

Virus IMPORTANCEThe development of vaccines for respiratory syncytial virus has been hampered by a lack of understanding of the requirements for eliciting high titers of neutralizing antibodies. The results of this study suggest that particle-associated RSV F protein containing mutations that stabilize the structure in a prefusion conformation may stimulate higher titers of protective antibodies than particles containing F protein in a wild-type or postfusion conformation. These findings indicate that the prefusion F protein assembled into VLPs has the potential to produce a successful RSV vaccine candidate.H uman respiratory syncytial virus (RSV) is the most significant cause of acute viral respiratory disease in infants and young children (1). There are from 34 to 65 million RSV infections resulting in acute lower respiratory disease requiring hospitalization and 160,000 to 199,000 deaths per year worldwide (2). Elderly populations are also at significant risk for serious RSV disease. In the United States, the virus accounts for 10,000 deaths and 14,000 to 60,000 hospitalizations per year among individuals more than 64 years of age (3-5). Indeed, RSV infection of this population is at least as significant as influenza virus infections. RSV infections result in high mortality rates in immunocompromised populations, particularly stem cell transplant recipients (6) and individuals with cardiopulmonary diseases (7). Despite the significance of RSV disease in different populations, there are no vaccines available.Failure to develop a licensed RSV vaccine is not due to lack of effort as numerous vaccine candidates have been characterized in preclinical and clinical studies spanning 5 decades (summarized in references 8 to 9). While many problems have uniquely hindered RSV vaccine development, a major hurdle has been a lack of understanding of requirements for generation of protective immunity to RSV infection. Many vaccine candidates are protective in animal models and, while stimulating antibody responses in humans, have failed to induce high levels of neutralizing antibodies and protection from virus challenge in human trials (reviewed in references 10 and 11). Although there are likely many reasons for these observations, one important issue has been a lack of clear understanding of the most effective form of the RSV antigens, particularly the F protein, for stimulating potent neutralizing antibodies.The paramyxovirus F protein is folded into a metastable conformation and upon fusion activation refolds, through a series of conformational intermediates, into the postfusion conformation, which is structurally very different from the prefusion form (12)(13)(14)(15)(16)(17)(18)(19). While it is logical to assume that the prefusion form of F protein should be more effective in stimulating optimally neutralizing antibodies, recent structural studies have shown that the postfusion form of the F protein contains at least some epitopes recognized by neutralizing monoclonal antibodies (17, 18). Thus, it has been a...

Efforts to develop a vaccine for respiratory syncytial virus (RSV) have primarily focused on the RSV fusion protein. The pre-fusion conformation of this protein induces the most potent neutralizing antibodies and is the focus of recent efforts in vaccine development. Following the first identification of mutations in the RSV F protein (DS-Cav1 mutant protein) that stabilized the pre-fusion conformation, other mutant stabilized pre-fusion F proteins have been described. To determine if there are differences in alternate versions of stabilized pre-fusion F proteins, we explored the use, as vaccine candidates, of virus-like particles (VLPs) containing five different pre-fusion F proteins, including the DS-Cav1 protein. The expression of these five pre-F proteins, their assembly into VLPs, their pre-fusion conformation stability in VLPs, their reactivity with anti-F monoclonal antibodies, and their induction of immune responses after the immunization of mice, were characterized, comparing VLPs containing the DS-Cav1 pre-F protein with VLPs containing four alternative pre-fusion F proteins. The concentrations of anti-F IgG induced by each VLP that blocked the binding of prototype monoclonal antibodies using two different soluble pre-fusion F proteins as targets were measured. Our results indicate that both the conformation and immunogenicity of alternative VLP associated stabilized pre-fusion RSV F proteins are different from those of DS-Cav1 VLPs.

Respiratory syncytial virus (RSV) is a significant respiratory pathogen but no vaccine is available. RSV infections present 2 major, unique problems. First, humans can experience repeated infections caused by the same virus sero-group indicating that protective memory responses to RSV infection are defective. Second, most people have been infected with RSV by age 5. Immune responses to these infections, while poorly protective, could impact the effectiveness of a vaccine. The goal of this study was to assess the generation of protective immune responses in mice previously infected with RSV by virus-like particle (VLP) vaccine candidates containing a stabilized pre-fusion form of the RSV F protein or a stabilized post-fusion F protein. We report that a single immunization of RSV-experienced animals with a stabilized pre-fusion F protein VLP stimulated high titers of neutralizing antibody while a single injection of a post-fusion F protein VLP or a second RSV infection only weakly stimulated neutralizing antibody titers. These results suggest that prior RSV infection can induce neutralizing antibody memory responses, which can be activated by pre-F protein VLPs but not by post-F protein VLPs or a subsequent infection. Thus the F protein conformation has a major impact on enhancing production of neutralizing antibodies in RSV-experienced animals. Furthermore, although both VLPs contained the same RSV G protein, the pre-F VLP stimulated significantly higher titers of total anti-G protein IgG than the post-F VLP in both naïve and RSV-experienced animals. Thus the F protein conformation also influences anti-G protein responses.

A comparative retrospective study to quantify the impact of Coronavirus Disease 2019 (COVID-19) on patient safety. We found a statistically significant increase in central line-associated blood stream infections and blood culture contamination rates during the pandemic. Increased length of stay and mortality was also observed during COVID-19.