Binding of porcine transmissible gastroenteritis virus by enterocytes from newborn and weaned piglets.
Enterocytes were harvested by chelation in a series of seven fractions from the tips of the villi to the crypts of the jejunum of newborn or weaned piglets. Binding of the low cell culture passaged Miller-6 strain of transmissible gastroenteritis virus (TGEV) to villous enterocytes from newborn piglets was at a high level, similar to that observed to cultured swine testis (ST) cells. Binding of the virus to cryptal enterocytes from newborn piglets or to villous or cryptal enterocytes from weaned piglets was significantly lower. In a competitive virus binding assay with radiolabelled virus, the binding of TGEV to ST cells was found to be saturable, while binding to MDBK cells, in which the virus fails to replicate, was at a lower level and was non-saturable. In the same assay, virus binding to the villous enterocytes from the jejunum of a newborn piglet was saturable, while binding to cryptal enterocytes from a newborn piglet, and to villous and cryptal enterocytes from a weaned piglet, was non-saturable. It was concluded that the high susceptibility of newborn piglets to TGEV infection, and the tropism of the virus for villous enterocytes, may relate to the presence of specific, saturable binding sites on the plasma membrane of villous enterocytes.