Cross-neutralization of four paramyxoviruses by a human monoclonal antibody.

Broadly neutralizing antibodies reactive against most and even all variants of the same viral species have been described for influenza and HIV-1 (ref. 1). However, whether a neutralizing antibody could have the breadth of range to target different viral species was unknown. Human respiratory syncytial virus (HRSV) and human metapneumovirus (HMPV) are common pathogens that cause severe disease in premature newborns, hospitalized children and immune-compromised patients, and play a role in asthma exacerbations. Although antisera generated against either HRSV or HMPV are not cross-neutralizing, we speculated that, because of the repeated exposure to these viruses, cross-neutralizing antibodies may be selected in some individuals. Here we describe a human monoclonal antibody (MPE8) that potently cross-neutralizes HRSV and HMPV as well as two animal paramyxoviruses: bovine RSV (BRSV) and pneumonia virus of mice (PVM). In its germline configuration, MPE8 is HRSV-specific and its breadth is achieved by somatic mutations in the light chain variable region. MPE8 did not result in the selection of viral escape mutants that evaded antibody targeting and showed potent prophylactic efficacy in animal models of HRSV and HMPV infection, as well as prophylactic and therapeutic efficacy in the more relevant model of lethal PVM infection. The core epitope of MPE8 was mapped on two highly conserved anti-parallel β-strands on the pre-fusion viral F protein, which are rearranged in the post-fusion F protein conformation. Twenty-six out of the thirty HRSV-specific neutralizing antibodies isolated were also found to be specific for the pre-fusion F protein. Taken together, these results indicate that MPE8 might be used for the prophylaxis and therapy of severe HRSV and HMPV infections and identify the pre-fusion F protein as a candidate HRSV vaccine

Clinical and morphological practices in the diagnosis of transplant-associated microangiopathy: a study on behalf of Transplant Complications Working Party of the EBMT.

Transplant-associated thrombotic microangiopathy (TA-TMA) is a life-threatening complication of allogeneic hematopoietic stem cell transplantation (HSCT). This study evaluated clinical and morphological practices of TA-TMA diagnosis in EBMT centers. Two questionnaires, one for transplant physician and one for morphologist, and also a set of electronic blood slides from 10 patients with TA-TMA and 10 control patients with various erythrocyte abnormalities, were implemented for evaluation. Seventeen EBMT centers participated in the study. Regarding criteria used for TA-TMA diagnosis, centers reported as follows: 41% of centers used the International Working Group (IWG) criteria, 41% used "overall TA-TMA" criteria and 18% used physician's decision. The threshold of schistocytes to establish TA-TMA diagnosis in the participating centers was significantly associated with morphological results of test cases evaluations (p = 0.002). The mean number of schistocytes reported from blood slide analyses were 4.3 ± 4.5% for TA-TMA cases (range 0-19.6%, coefficient of variation (CV) 0.7) and 1.3 ± 1.6% for control cases (range 0-8.3%, CV 0.8). Half of the centers reported schistocyte levels below 4% for 7/10 TA-TMA cases. The intracenter variability was low, indicating differences in the institutional practices of morphological evaluation. In conclusion, the survey identified the need for the standardization of TA-TMA morphological diagnosis