Flavivirus cross‐reactivity in serological tests and Guillain‐Barré syndrome in a hematopoietic stem cell transplant patient: A case report

Serological diagnosis of flavivirus infection is a challenge, particularly in the context of a disease associated with immune response enhancement in a transplant patient, where aspects such as previous flavivirus infections may be involved with the outcome. We report a case of a pediatric patient who developed Guillain‐Barré syndrome (GBS) after matched‐unrelated hematopoietic stem cell transplantation (HSCT). The patient lives in a Brazilian region that is experiencing an epidemic of Zika virus (ZIKV) and dengue virus (DENV). Because an increasing number of cases of GBS, likely triggered by ZIKV infection, are being reported in Brazil, samples from the patient were tested for both ZIKV and DENV infection. Serological assays strongly suggested a recent ZIKV infection, although infection by DENV or co‐infection with both viruses cannot be ruled out. The presence of anti‐DENV immunoglobulin‐G in donor serum led to the hypothesis that antibodies from the donor could have enhanced the severity of the ZIKV infection. This hypothesis is in agreement with the recent findings that DENV sero‐cross‐reactivity drives antibody‐dependent enhancement of ZIKV infection. These findings highlight the need for discussion of the indication to perform previous flavivirus tests in HSCT donors, especially in areas where ZIKV and other flaviviruses co‐circulate.     

Novel monoclonal antibodies that bind to wild and fixed rabies virus strains

Ten monoclonal antibodies (MAbs) against rabies virus, including IgG3κ, IgG2aκ, IgMκ, and an IgG2bκ isotype, were produced and characterized using neutralization, ELISA, immunodot-blot, and immunofluorescence assays. MAb 8D11, which recognized rabies virus glycoprotein, was found to neutralize rabies virus in vitro. When submitted to an immunofluorescence assay, seven MAbs showed different reactivity against 35 Brazilian rabies virus isolates. Three MAbs (LIA 02, 3E6, and 9C7) only failed to recognize one or two virus isolates, whereas MAb 6H8 was found to be reactive against all virus isolates tested. MAbs were also evaluated for their immunoreactivity against fixed rabies virus strains present in human and veterinary commercial vaccines. MAbs LIA 02, 6H8, and 9C7 reacted against all vaccine strains, while the remaining MAbs recognized at least 76% of vaccine strains tested. This research provides a set of MAbs with potential application for improving existing or developing new diagnostic tests and immunoassays.     

Seroconversion of rheumatoid arthritis patients after yellow fever vaccination

Clinical Rheumatology - Vaccination is a current strategy used to prevent infections in patients with immune-mediated rheumatic diseases. However, the use of live-attenuated vaccines prepared from...     

Production and characterization of monoclonal antibodies against the recombinant nucleoprotein of Araucaria hantavirus

Hantaviruses are rodent-borne RNA viruses that cause hemorrhagic fever with renal syndrome (HFRS) or hantavirus pulmonary syndrome (HPS). From the first detection of infection in Brazil in 1993 until 2009, 1161 cases of HPS have been reported, with mortality rates of around 40%. Currently, due to the absence of a vaccine or specific antiviral therapy, the only way to reduce mortality by hantavirus infection is a fast and precise diagnosis that allows for supportive clinical health care. To improve the detection of hantavirus infection, we developed monoclonal antibodies (Mabs) against the nucleoprotein (rNΔ₈₅) of the Araucaria hantavirus strain (ARAUV). The specificity of generated Mabs for rNΔ₈₅ was demonstrated by western blot, indirect immunofluorescence and immunohistochemistry. These are the first monoclonal antibodies to be produced and characterized against the South American hantavirus strain, and may be of special interest in the development of diagnostic assays and epidemiological studies.