Virus specific and bystander-B cell activation account for the massive plasmablast response during human Hantavirus infection

GARCÍA M; IGLESIAS A; LANDONI V; BELLOMO C; BRUNO A; CÓRDOBA MT; SASIAIN MC; SCHIERLOH P; MARTÍNEZ VP

Buenos Aires

Congreso; LXII Reunión Científica Anual de la Sociedad Argentina de Inmunología.; 2015

Sociedad Argentina de Inmunología y Sociedad Francesa de Immunología

Background: In a recent study, we described the presence of huge amounts of circulating plasmablast (PB) in Hantavirus pulmonary syndrome (HPS) patients infected with local Andes virus (ANDV) strains. This strong PB response was time dependent with peak values around one week after symptoms onset but it was unrelated with viremia, virus strains and immunoglobulin (Ig)M-specific serological status. Therefore, to better understand the origin of such reactive cellular response, herein we analyze the immunoreactivity of PB circulating in ANDV+ patients. Methods: ANDV+ patients (n=18), healthy subjects (HS, n=12), influenza vaccinated HS (v-HS, n=12), acute respiratory subjects (ARS, n=15) and tuberculosis patients (TB, n=10) was enrolled after informed consent and their blood samples were transfixed for protein stabilization. Red blood cells were lysed and intracytoplasmatic antibodies (cyAb) from leucocytes were obtained by non-anionic detergent extraction. This new method was properly validated by comparing with the gold-standard functional assay (ELISPOT). CyAb were tested by indirect ELISA against ANDV specific antigens (Ags) (n=3) and unrelated Ags (n=8). Results: As expected, only ANDV+ PB derived cyAb reacted with all 3 virus specific Ags (p 0.0005). Interestingly, we also observe that most ANDV+ PB derived cyAb also reacted with all the unrelated Ags tested. Furthermore, the median values of ANDV+-cyAb immunoreactivity against unrelated Ags were higher than v-HS- (p 0.001), HS- (p 0.0001), ARS- (p 0.001) and TB-cyAb (p 0.001). Conclusions: The strong immunoreactivity of cyAb against virus related and unrelated Ags indicates that a polyclonal activation of B cells takes place during acute phase of HPS in ANDV+ patients.