Respiratory Viral Infections in Transplant Recipients

New Approaches to Respiratory Syncytial Virus Prevention and Treatment

There have been several recent advances in the prevention of lower respiratory tract disease (LRTD) due to respiratory syncytial virus (RSV) infection in older adults and young children. Three different vaccines are now approved for use in older adults; one of these vaccines is also approved for use in pregnant individuals for the prevention of LRTD due to RSV in their infants. In addition, a new monoclonal antibody is available to prevent RSV LRTD in infants born during or entering their first RSV season and in children up to 24 months of age who remain vulnerable to severe RSV disease through their second RSV season. Despite these advances in prevention efforts, specific antiviral treatment options for RSV infection remain limited. Several promising compounds remain in development.

Pneumonia in Transplant Recipients: A Comprehensive Review of Diagnosis and Management

Transplant recipients have an increased risk of complications, including graft dysfunction and infections, which can be life-threatening if not recognized early. Pneumonia ranks as one of the most frequent complications in both solid organ and hematopoietic stem cell transplants. Clinical symptoms manifest late during infections in immunocompromised patients. An aggressive approach centered on early confirmatory diagnosis and a low threshold for empiric therapy is often the most effective strategy. The isolation of a pathogen in an upper airway sample does not necessarily mean the same organism is responsible for pneumonia. Viruses such as CMV (cytomegalovirus virus) may function as co-pathogens for opportunistic infections in transplant recipients in addition to causing their own primary infectious syndrome. Furthermore, some viruses exhibit immunomodulatory effects that can affect the graft function. Given the exhaustive list of causative pathogens responsible for pneumonia, the best approach to the diagnosis is to have a conceptual framework that includes a detailed history, such as the type of transplant, degree of immunosuppression, antimicrobial prophylaxis, risk factors, time of presentation since transplantation and the radiographic pattern on the CT chest (computer tomography of the chest). Management depends predominantly on the degree of antimicrobial resistance, drug-to-drug interaction, and adjustments to the immunosuppression.

Consistent FFP2-masking as part of reducing viral respiratory infections on medical wards for allogeneic hematopoietic stem cell transplantation

Patients undergoing allogenic hematopoietic stem cell transplantation (allo-HSCT) are highly susceptible to infections. The consequent use of masks on wards for allo-HSCT has been controversial in the past decades and was not common before the COVID-19 pandemic. We retrospectively compared incidence and outcomes of viral respiratory infections during allo-HSCT on our specialized ward between 01/2018 and 09/2020 to the era of FFP2 masking between 10/2020 and 10/2022 covering similar seasons of the year. Each group consisted of 150 matched patients. The usage of FFP2 masks reduced the incidence of viral respiratory infections from 22.1 to 2.1% (p < 0.005). This reduced the time on ward from a median of 26 days to 23.5 days (p = 0.002). It also resulted in less use of CT-scans (p = 0.003) and bronchoalveolar lavage procedures (p = 0.057). Median time to proof of infection was 21 days after admission in both groups. No difference was detected in progression free survival, hospital survival or non-relapse mortality (p = 0.78). Our retrospective results indicate that FFP2 masks worn by patients and hospital staff may help to significantly reduce the incidence of viral respiratory infections, including COVID-19, shorten the in-hospital time, and reduce costs without affecting survival.

Immunogenicity of a recombinant plant-produced respiratory syncytial virus F subunit vaccine in mice

Respiratory syncytial virus (RSV) is a highly infectious respiratory virus that causes serious illness, particularly in young children, elderly people, and those with immunocompromised individuals. RSV infection is the leading cause of infant hospitalization and can lead to serious complications such as pneumonia and bronchiolitis. Currently, there is an RSV vaccine approved exclusively for the elderly population, but no approved vaccine specifically designed for infants or any other age groups. Therefore, it is crucial to continue the development of an RSV vaccine specifically tailored for these populations. In this study, the immunogenicity of the two plant-produced RSV-F Fc fusion proteins (Native construct and structural stabilized construct) were examined to assess them as potential vaccine candidates for RSV. The RSV-F Fc fusion proteins were transiently expressed in Nicotiana benthamiana and purified using protein A affinity column chromatography. The recombinant RSV-F Fc fusion protein was recognized by the monoclonal antibody Motavizumab specific against RSV-F protein. Moreover, the immunogenicity of the two purified RSV-F Fc proteins were evaluated in mice by formulating with different adjuvants. According to our results, the plant-produced RSV-F Fc fusion protein is immunogenic in mice. These preliminary findings, demonstrate the immunogenicity of plant-based RSV-F Fc fusion protein, however, further preclinical studies such as antigen dose and adjuvant optimization, safety, toxicity, and challenge studies in animal models are necessary in order to prove the vaccine efficacy.