Bat-mouse bone marrow chimera: a novel animal model for dissecting the uniqueness of the bat immune system

Yong, Kylie Su Mei; Ng, Justin Han Jia; Her, Zhisheng; Hey, Ying Ying; Tan, Sue Yee; Tan, Wilson Wei Sheng; Irac, Sergio Erdal; Liu, Min; Chan, Xue Ying; Gunawan, Merry; Foo, Randy Jee Hiang; Low, Dolyce Hong Wen; Mendenhall, Ian Hewitt; Chionh, Yok Teng; Dutertre, Charles-Antoine; Chen, Qingfeng; Wang, Lin-Fa

While there is an urgent need to carry out in-depth bat research to unlock some of the mysteries associated with the above-stated observations and preliminary findings, bat research suffers major obstacles due to the lack of bat-specific research tools (such as antibodies and specific cell lines) and, more importantly, the lack of experimental animal system due to the outbreed nature and low reproduction rates of bats. To accelerate bat research in the immediate future, we propose to fill the gap using the bat-mouse platform to provide a genetically consistent Figure 4 . Determination of antigen-specific antibody response in bat-mice. Bat BM cells were isolated and injected into sub-lethally irradiated NSG pups at 1 × 10 5 cells per mouse (n = 10). Twenty-four weeks post injection, the mice were cheek bled and blood was prepared and analyzed by flow cytometry. (a) Shown is the plot of chimerism levels within the peripheral blood of individual mouse before immunization. Each symbol represents one mouse and the horizontal line indicates the mean value. (b) Bat-mice (n = 10) and NSG mice (n = 5) were immunized via intraperitoneal injection with NP-KLH, using IFA as an adjuvant. Sera were collected from immunized bat-mice and NSG controls 2 weeks after the second booster. Optical density 450 (OD 450 ) levels of NP-specific antibodies were quantified by ELISA. Each symbol represents one mouse and the horizontal line indicates the mean value. (c) ELISA titres determined for each of the immunized bat-mice with the non-immunized bat-mice pre-bleed sera negative control. The titre was calculated from the reciprocal of the greatest dilution that yielded the ELISA reading ≥3 standard deviations above the negative control mean.