Growth of dengue type 2 virus isolates in human peripheral blood leukocytes correlates with severe and mild dengue disease.

We tested three dengue type 2 (DEN-2) isolates from children with clinically apparent but mild secondary dengue infections, and 10 isolates from children with moderately severe dengue hemorrhagic fever, and noted significant growth differences in peripheral blood leukocytes, but not in C6/36 cells. We also observed cytopathic effects in C6/36 cells that correlated with disease severity. These preliminary observations suggest the possibility that viral factors, whether surface antigens, attachment sites for entry into leukocytes, or intrinsic replication properties in human mononuclear phagocytes, might contribute to enhanced DEN infection and to the severity of the disease.