Genetic modification of non-human primates (NHP) paves the way for realistic disease models. The common marmoset is a NHP species increasingly used in biomedical research. Despite the invention of RNA-guided nucleases, one strategy for protein overexpression in NHP is still lentiviral transduction. We generated three male and one female enhanced green fluorescent protein (EGFP)-transgenic founder marmosets via lentiviral transduction of natural preimplantation embryos. All founders accomplished germline transmission of the transgene by natural mating, yielding 20 transgenic offspring together (in total, 45 pups; 44% transgenic). This demonstrates that the transgenic gametes are capable of natural fertilization even when in competition with wildtype gametes. Importantly, 90% of the transgenic offspring showed transgene silencing, which is in sharp contrast to rodents, where the identical transgene facilitated robust EGFP expression. Furthermore, we consistently discovered somatic, but so far, no germ cell chimerism in mixed wildtype/transgenic litters. Somatic cell chimerism resulted in false-positive genotyping of the respective wildtype littermates. For the discrimination of transgenic from transgene-chimeric animals by polymerase chain reaction on skin samples, a chimeric cell depletion protocol was established. In summary, it is possible to establish a cohort of genetically modified marmosets by natural mating, but specific requirements including careful promoter selection are essential.

Non-human primates (NHPs) serve as embryo donors for embryo collection in order to mimic genetic diseases in humans by genetic modification. Reproductive health of the embryo donors is crucial, and chronic distress needs to be avoided. Embryo retrieval rates (ERR), anti-Müllerian hormone (AMH) concentrations, cortisol levels, and body weight fluctuations were assessed as markers for fertility and distress. With regard to successful embryo retrievals (total n = 667), the animals were either used for extended periods (long-term group; LTG) or only for short periods (short-term group; STG). Retrospective evaluation expectedly showed that animals in the LTG had a higher ERR than animals in the STG (p < 0.0001). Importantly, ERR in the LTG remained stable throughout the experimental period, and high embryo rates were already encountered during the first year of experimental use (p = 0.0002). High ERR were associated with high AMH and low cortisol levels, and minimal body weight fluctuations following anesthesia, indicating a superior ability of the LTG animals to handle distress. We conclude that the long-term experimental use of marmosets does not impair their fertility or health status per se, supporting the view that animal reuse can be in accordance with the 3R-principle, implying reduction, replacement, and refinement in animal experimentation.

Background: Extensive analysis of eosinophilic airway inflammation in human-relevant animal models is required to test novel, human-specific pharmaceuticals. This requires species, which show high genetic homology to humans such as non-human primates. Efficacy assessment of novel human-specific biologicals in eosinophilic airway inflammation is currently performed in the cost-intensive macaque asthma model. Objective: The present study investigated whether marmoset monkeys ( Callithrix jacchus ), a small-bodied non-human primate species from the New World, develop eosinophilic airway inflammation in response to house dust mite allergen exposure (HDM, Dermatophagoides pteronyssinus ). Methods: Marmoset monkeys were sensitized against HDM by subcutaneous (s.c.) injection and subsequent intratracheal (i.t.) HDM aerosol challenges. Airway and systemic immunologic reactions were monitored and sensitivity towards glucocorticoid therapy was assessed. The pulmonary immunologic response was analyzed by repetitive bronchoalveolar lavage (BAL). Results: Bronchoalveolar lavage fluid (BALF) exhibited increased levels of eosinophils, mast cells, and lymphocytes, as well as interleukin (IL)-13 after HDM challenges, compared to negative controls. The systemic immunologic response was assessed in peripheral blood mononuclear cells derived from sensitized animals, which secreted increased IL-13 and IFN-γ upon allergen stimulation in contrast to non-sensitized negative control animals. Although IgE was not detectable, HDM-specific serum IgG was elevated in sensitized animals. Both airway and systemic responses were reduced by treatment with glucocorticoids. However, lung function and pathological analyses did not reveal significant differences between groups. Conclusion: In conclusion, marmoset monkeys developed a mild HDM-induced eosinophilic airway inflammation useful for efficacy testing of novel human-specific biologicals.

Guillain-Barré syndrome (GBS) is a rare, mainly acute inflammatory polyneuropathy in humans. It is frequently post-infectious with auto antibodies being formed against myelin sheaths, resulting in a progressive and more-or-less severe paralysis of the motor neuron and cranial nerves. Mortality is low and 60 % of the patients recover completely from the disease after intensive treatment.In animals, there are a few diseases that closely resemble GBS, but cases of GBS in monkeys seem to be scarce. In this case report, the clinical course of a progressive tetraplegia in a male rhesus macaque is described. Clinical, cerebrospinal fluid (CSF), electroneurography (ENG) and electromyography (EMG), and pathological findings revealed symptoms very similar to human GBS.