Establishment of an immortalized red river hog blood-derived macrophage cell line

Red river hogs (RRHs) (Potamochoerus porcus), a wild species of Suidae living in Africa, have grabbed much attention as an animal that harbors African swine fever virus (ASFV) as natural hosts. When ASFV infects domestic pigs and wild boars, it proliferates within macrophages, a type of immune cells, and infected pigs rapidly die suffering from symptoms such as fever and hemorrhage. On the other hand, ASFV infection in RRHs is asymptomatic and does not cause death, suggesting that RRH macrophages may have a protective mechanism against ASFV infection.

In vitro cell cultures of porcine macrophages are generally used in ASFV research. However, inducing macrophage proliferation in vitro was challenging as extensive efforts from researchers and numerous pigs are required to obtain sufficient number of macrophages. In this context, NARO developed the first immortalized porcine kidney macrophage cell line, IPKM, that has an almost unlimited proliferation capacity in vitro. The use of the IPKM cell line has improved the efficiency of research material collection and significantly advanced ASFV research.

To further advance ASFV research, in collaboration with Yokohama Zoological Gardens ZOORASIA, NARO has successfully developed a novel macrophage cell line, RZJ/IBM, derived from precious surplus blood collected from a male RRH during health check. It was also demonstrated that ASFV proliferation was far less vigorous in RZJ/IBM cell cultures compared with IPKM cell cultures. Dr. Takato Takenouchi, the corresponding author of this article, remarked, "Detailed comparative analysis of the differential responses between these two cell lines will bring us closer to the mystery behind the asymptomatic nature of ASFV-infected RRHs”. This elucidation is expected to pave way for the prevention of ASF and the development of an ASF vaccine.  

About National Agriculture and Food Research Organization (NARO)

NARO is the core institute in Japan for conducting research and development in a wide range of fields, from basic to applied, for the development of agriculture and food industries.

For more information, visit https://www.naro.go.jp/english/index.html .