In vivo replication of African swine fever virus (Malawi '83) in neutrophils.

The presence of virus replication centers in neutrophils from pigs inoculated with a highly virulent strain of African swine fever virus is described for the first time in vivo. Virus antigens were observed from 3 days post-inoculation (dpi) onwards by means of an immunohistochemical technique. At this time (3 dpi), transmission electron microscopy studies revealed the presence of large amounts of neutrophils in the vascular lumens. At 5 and 7 dpi, neutrophils with phagosomes frequently contained virus particles. In addition, within the cytoplasm of some mature and immature neutrophils, both viral particles and virus replication centers were observed at 5 and 7 dpi.