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Because nonhuman primates have been thought to be invulnerable to infection with pig endogenous retroviruses (PERV), it has been difficult to develop a model for studying the risk of PERV transmission during xenotransplantation. Now, researchers report a solution to this problem.

In the August issue of the Journal of Virology, an international team headed by Ulrich Martin, MD of Hannover (Germany) Medical School described experiments demonstrating that human, gorilla, and Papio hamadryas baboon primary skin fibroblasts as well as baboon B-cell lines can be infected with PERV.

"Since apes have been ruled-out as animal models for ethical and practical reasons, we...concentrated on the susceptibility of baboon cells to PERV infection," the researchers wrote. "Our data provide clear evidence that baboon cells, similar to human cells, are permissive for PERV infection."

The fact that 2 baboon B-lymphocyte cell lines were permissive for infection is particularly important, according to the investigators. "This cell type represents one of the cell types which will, during xenotransplantation, come in close contact with porcine endothelial cells, which...have been shown to release infectious PERV in vitro," they said.

"The baboon probably represents the best animal model currently available for preclinical risk assessment," Martin and colleagues concluded.