# Immunodeficient Rabbit Models: History, Current Status and Future Perspectives
## 4 The Birth of Immunodeficient Rabbits  
The rabbit (_Orytcolagus Cuniculus_) is a classic laboratory animal model species and is increasingly becoming a translational model of choice for bridging the gap between rodent models and larger animal models [62; 63; 64; 65; 66; 67; 68; 69; 70; 71]. The method to produce transgenic rabbits by pronuclear microinjection is well-established and comprehensively described [72]. The significant advantages of rabbit models over ID mouse models are their longer lifespan and larger size. A New Zealand White (NZW) rabbit housed in a specific pathogen-free (SPF) animal facility can live beyond six years, and adult NZW rabbits are similar in weight and size to human infants. In the context of ID, rabbit models would extend studies past one year, such as those required for gene therapy development, and allow sophisticated xenotransplantation procedures. We also note that the rabbit is a classic animal model for the study of immunology [73; 74; 75]. They are used for the study of viral [76; 77; 78] and bacterial infectious diseases and in particular _S. aureus_ infections in the lungs, which is a significant pathogen in human SCID patients [79]; therefore an ID rabbit model may better reflect _S. aureus_ infection-related pathologies in immunodeficient patients than do mouse models. Compared to other large animals such as pigs and non-human primates, the rabbit is a more affordable \begin{table}
\begin{tabular}{l c c c c c c c c c c c c} \hline \hline
**Year** & **Pre 2009** & **2009** & **2010** & **2011** & **2012** & **2013** & **2014** & **2015** & **2016** & **2017** & **2018** & **2019** & **2020** \\ \hline \multirow{2}{*}{Method} & Tg: transgenic & Z: ZFN & T: TALEN & C: Cas9 & & & & & & & & \\ \hline \hline \multicolumn{12}{l}{VDJ-Cmu} & Tg [57] & & & & & & & & & & & \\ \hline \multicolumn{12}{l}{IL2 RG} & & & & & & & & & & & & \\ \multicolumn{12}{l}{Rag1} & & & & & & & & & & & & \\ \multicolumn{12}{l}{Rag2} & & & & & & & & & & & & \\ \multicolumn{12}{l}{IgM} & & Z [61] & & & & & & & & & & \\ \multicolumn{12}{l}{Prkdc} & & & & & & & & & & & & \\ \multicolumn{12}{l}{Foxn1} & & & & & & & & & & & & \\ \hline \multicolumn{12}{l}{VDJ-Cmu: a transgene that codes the V, D, J and the constant region of the mu chain of immunoglobulin; IL2 RG: interleukin 2 receptor subunit gamma; Rag1: recombination activating gene 1; Rag2: recombination activating gene 2; IgM: immunoglobulin M; Prkdc: protein kinase, DNA-activated, catalytic subunit; Foxn1: forkhead box protein N1.} \\ \end{tabular}
\end{table} 
Table 2: Production of immunodeficient rabbits. The “Method” row indicates the debut year of the method. Tg: transgenic, refers to the conventional method used in transgenic animal production, without the use of gene editing nucleases or any other gene targeting methods. lab animal species that can be easily housed in most research institutes. In addition, rabbits possess a short gestational period of 30-31 days, and routinely produce relatively large litters of 4 to 12 kits, allowing efficient herd expansion. Although these features make ID rabbits a promising model to be developed, the production of gene-targeted transgenic (GTT) (e.g., knockout, knock-in) rabbits has been a challenge. Efforts to produce GTT rabbits date back to the 1980s, but unfortunately, all gene targeting attempts failed until ZFN became available in 2009. This is mainly due to the lack of germline ESCs [80], and the extremely low efficiency of somatic cell nuclear transfer (SCNT) in rabbits [81]. ESCs are the primary tool to generate GTT mice, and SCNT has been successfully applied to generate KO animals in species lacking germline transmitting ESCs such as pigs [82; 83; 84], sheep [85; 86] and cattle [87], but not in rabbits. As a result, no ID rabbits have yet been produced by the ESC or SCNT approach. Interestingly, the laboratory of [PERSON] at Loyola University (Chicago, IL, USA), who first established a working protocol to establish rabbit monoclonal antibodies, generated the first ID rabbit line accidentally [57].