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Concept: Rhesus Macaque


Men have two practical choices for contraception; the condom which has a high typical use failure rate or vasectomy. New male hormonal and non-hormonal contraceptives are under development that target either the production of sperm (spermatogenesis) or the delivery of sperm. One particular target is the sperm protein EPPIN, which is present on the surface of human spermatozoa. EP055 is a small organic compound that targets EPPIN on the surface of sperm and inhibits motility. EP055 was tested in cynomolgus (Macaca fascicularis) males to determine its plasma half-life after intravenous (i.v.) infusion of a single dose and for binding to its target tissues. Our initial study demonstrated a plasma half-life for EP055 of 10.6 minutes. In a second study examination of macaque testis, epididymis, and plasma after i.v. infusion of a single dose of compound EP055 (63.25 mg/kg) demonstrated that EP055 was detected in testis and epididymis two hours and six hours post-infusion. We initiated a trial in rhesus (Macaca mulatta) males to assess the availability of EP055 in semen and its effect on sperm motility as a measure of the drug’s efficacy. Four macaques were infused with a low dose (75-80 mg/kg) followed by a recovery period and a subsequent high dose (125-130 mg/kg) of EP055. After high dose administration, sperm motility fell to approximately 20% of pretreatment levels within 6 hours post-infusion; no normal motility was observed at 30 hours post-infusion. Recovery of sperm motility was obvious by 78 hours post-infusion; with full recovery in all animals by 18 days post-infusion. EP055 has the potential to be a male contraceptive that would provide a reversible, short-lived pharmacological alternative.

Concepts: Birth control, Sperm, Macaque, Enzyme inhibitor, Spermatozoon, Semen, Primate, Rhesus Macaque


Zika virus is present in urine, saliva, tears, and breast milk, but the transmission risk associated with these body fluids is currently unknown. Here we evaluate the risk of Zika virus transmission through mucosal contact in rhesus macaques. Application of high-dose Zika virus directly to the tonsils of three rhesus macaques results in detectable plasma viremia in all animals by 2 days post-exposure; virus replication kinetics are similar to those observed in animals infected subcutaneously. Three additional macaques inoculated subcutaneously with Zika virus served as saliva donors to assess the transmission risk from contact with oral secretions from an infected individual. Seven naive animals repeatedly exposed to donor saliva via the conjunctivae, tonsils, or nostrils did not become infected. Our results suggest that there is a risk of Zika virus transmission via the mucosal route, but that the risk posed by oral secretions from individuals with a typical course of Zika virus infection is low.Zika virus (ZIKV) is present in body fluids, including saliva, but transmission risk through mucosal contact is not well known. Here, the authors show that oropharyngeal mucosal infection of macaques with a high ZIKV dose results in viremia, but that transmission risk from saliva of infected animals is low.

Concepts: Microbiology, Infection, Milk, Macaque, Primate, Breast, Rhesus Macaque, Body fluids


Without an approved vaccine or treatment, Ebola outbreak management has been limited to palliative care and barrier methods to prevent transmission. These approaches, however, have yet to end the 2014 outbreak of Ebola after its prolonged presence in West Africa. Here we show that a combination of monoclonal antibodies (ZMapp), optimized from two previous antibody cocktails, is able to rescue 100% of rhesus macaques when treatment is initiated up to 5 days post-challenge. High fever, viraemia and abnormalities in blood count and blood chemistry were evident in many animals before ZMapp intervention. Advanced disease, as indicated by elevated liver enzymes, mucosal haemorrhages and generalized petechia could be reversed, leading to full recovery. ELISA and neutralizing antibody assays indicate that ZMapp is cross-reactive with the Guinean variant of Ebola. ZMapp exceeds the efficacy of any other therapeutics described so far, and results warrant further development of this cocktail for clinical use.

Concepts: Immune system, Antibody, Macaque, Primate, Rhesus Macaque, Ebola, Viral hemorrhagic fever, Crab-eating Macaque


Spinal cord injury disrupts the communication between the brain and the spinal circuits that orchestrate movement. To bypass the lesion, brain-computer interfaces have directly linked cortical activity to electrical stimulation of muscles, and have thus restored grasping abilities after hand paralysis. Theoretically, this strategy could also restore control over leg muscle activity for walking. However, replicating the complex sequence of individual muscle activation patterns underlying natural and adaptive locomotor movements poses formidable conceptual and technological challenges. Recently, it was shown in rats that epidural electrical stimulation of the lumbar spinal cord can reproduce the natural activation of synergistic muscle groups producing locomotion. Here we interface leg motor cortex activity with epidural electrical stimulation protocols to establish a brain-spine interface that alleviated gait deficits after a spinal cord injury in non-human primates. Rhesus monkeys (Macaca mulatta) were implanted with an intracortical microelectrode array in the leg area of the motor cortex and with a spinal cord stimulation system composed of a spatially selective epidural implant and a pulse generator with real-time triggering capabilities. We designed and implemented wireless control systems that linked online neural decoding of extension and flexion motor states with stimulation protocols promoting these movements. These systems allowed the monkeys to behave freely without any restrictions or constraining tethered electronics. After validation of the brain-spine interface in intact (uninjured) monkeys, we performed a unilateral corticospinal tract lesion at the thoracic level. As early as six days post-injury and without prior training of the monkeys, the brain-spine interface restored weight-bearing locomotion of the paralysed leg on a treadmill and overground. The implantable components integrated in the brain-spine interface have all been approved for investigational applications in similar human research, suggesting a practical translational pathway for proof-of-concept studies in people with spinal cord injury.

Concepts: Spinal cord, Muscle, Macaque, Primate, Rhesus Macaque, Paralysis, Medulla oblongata, Locomotion


As the predominant aetiological agent of the common cold, human rhinovirus (HRV) is the leading cause of human infectious disease. Early studies showed that a monovalent formalin-inactivated HRV vaccine can be protective, and virus-neutralizing antibodies (nAb) correlated with protection. However, co-circulation of many HRV types discouraged further vaccine efforts. Here, we test the hypothesis that increasing virus input titres in polyvalent inactivated HRV vaccine may result in broad nAb responses. We show that serum nAb against many rhinovirus types can be induced by polyvalent, inactivated HRVs plus alhydrogel (alum) adjuvant. Using formulations up to 25-valent in mice and 50-valent in rhesus macaques, HRV vaccine immunogenicity was related to sufficient quantity of input antigens, and valency was not a major factor for potency or breadth of the response. Thus, we have generated a vaccine capable of inducing nAb responses to numerous and diverse HRV types.

Concepts: Immune system, Antiviral drug, Influenza, Primate, Rhesus Macaque, Common cold, Rhinovirus, Pleconaril


Primates (including humans) scratch when stressed. So far, such scratching has been seen as a by-product of physiological processes associated with stress, and attributed proximate, regulatory function. However, it is possible that others could use this relationship between scratching and stress as an indication of the animal’s stress state, and thus scratching could potentially have social function. As a test of this theory, we measured the production of, and social responses to scratching in a group of free-ranging rhesus macaques (Macaca mulatta). Firstly, we found that the likelihood of scratching was greater around periods of heightened social stress, such as being in proximity to high-ranking individuals, or non-friends. Secondly, when macaques scratched, subsequent interactions were less likely to be aggressive and more likely to be affiliative. Potential attackers may avoid attacking stressed individuals as stressed individuals could behave unpredictably or be weakened by their state of stress (rendering aggression risky and/or unnecessary). Observable stress behaviour could therefore have additional adaptive value by reducing the potential for escalated aggression, benefiting both senders and receivers by facilitating social cohesion. This basic ability to recognise stress in others could also be an important component in the evolution of social cognition such as empathy.

Concepts: Psychology, Sociology, Macaque, Primate, Rhesus Macaque, Monkeys in space, Old World monkey, Cercopithecine monkeys


A genital herpes vaccine is urgently needed to prevent pain and suffering, reduce the incidence of neonatal herpes, and decrease the risk of HIV acquisition and transmission that accompanies genital infection. We evaluated a trivalent HSV-2 subunit antigen vaccine administered with CpG and alum in rhesus macaques and guinea pigs. The vaccine contains glycoproteins C, D and E (gC2, gD2, gE2) to block virus entry by gD2 and immune evasion by gC2 and gE2. In rhesus macaques, the trivalent vaccine induced plasma and mucosa neutralizing antibodies, antibodies that block gC2 and gE2 immune evasion activities, and stimulated CD4 T cell responses. After intravaginal challenge, a self-limited vaginal infection of brief duration was detected by histopathology and immunohistochemistry in naïve, but not in trivalent immunized macaques. Vaccine efficacy was evaluated in female guinea pigs. Animals were mock immunized, or immunized with gD2, the trivalent vaccine or the trivalent vaccine followed by a booster dose of gD2 (trivalent + gD2). The trivalent and trivalent + gD2 groups were 97% and 99% efficacious, respectively in preventing genital lesions and both outperformed gD2 alone. As a marker of transmission risk, vaginal swabs were evaluated daily for HSV-2 DNA and replication competent virus between five and seven weeks after challenge. HSV-2 DNA shedding was reduced in all groups compared with mock. Shedding of replication competent virus occurred on fewer days in the trivalent than gD2 immunized animals while the trivalent + gD2 group had no shedding of replication competent virus. Overall, the trivalent group had genital lesions on < 1% days and shedding of replication competent virus on 0.2% days. The vaccine has outstanding potential for prevention of genital herpes in humans.

Concepts: Immune system, Antibody, Virus, Vaccine, Vaccination, Immunology, Herpes simplex, Rhesus Macaque


Face perception in humans and nonhuman primates is rapid and accurate [1-4]. In the human brain, a network of visual-processing regions is specialized for faces [5-7]. Although face processing is a priority of the primate visual system, face detection is not infallible. Face pareidolia is the compelling illusion of perceiving facial features on inanimate objects, such as the illusory face on the surface of the moon. Although face pareidolia is commonly experienced by humans, its presence in other species is unknown. Here we provide evidence for face pareidolia in a species known to possess a complex face-processing system [8-10]: the rhesus monkey (Macaca mulatta). In a visual preference task [11, 12], monkeys looked longer at photographs of objects that elicited face pareidolia in human observers than at photographs of similar objects that did not elicit illusory faces. Examination of eye movements revealed that monkeys fixated the illusory internal facial features in a pattern consistent with how they view photographs of faces [13]. Although the specialized response to faces observed in humans [1, 3, 5-7, 14] is often argued to be continuous across primates [4, 15], it was previously unclear whether face pareidolia arose from a uniquely human capacity. For example, pareidolia could be a product of the human aptitude for perceptual abstraction or result from frequent exposure to cartoons and illustrations that anthropomorphize inanimate objects. Instead, our results indicate that the perception of illusory facial features on inanimate objects is driven by a broadly tuned face-detection mechanism that we share with other species.

Concepts: Brain, Human, Perception, Macaque, Primate, Rhesus Macaque, Monkeys in space, Old World monkey


The efficacy and accepted regimen of antibiotic treatment for Lyme disease has been a point of significant contention among physicians and patients. While experimental studies in animals have offered evidence of post-treatment persistence of Borrelia burgdorferi, variations in methodology, detection methods and limitations of the models have led to some uncertainty with respect to translation of these results to human infection. With all stages of clinical Lyme disease having previously been described in nonhuman primates, this animal model was selected in order to most closely mimic human infection and response to treatment. Rhesus macaques were inoculated with B. burgdorferi by tick bite and a portion were treated with recommended doses of doxycycline for 28 days at four months post-inoculation. Signs of infection, clinical pathology, and antibody responses to a set of five antigens were monitored throughout the ~1.2 year study. Persistence of B. burgdorferi was evaluated using xenodiagnosis, bioassays in mice, multiple methods of molecular detection, immunostaining with polyclonal and monoclonal antibodies and an in vivo culture system. Our results demonstrate host-dependent signs of infection and variation in antibody responses. In addition, we observed evidence of persistent, intact, metabolically-active B. burgdorferi after antibiotic treatment of disseminated infection and showed that persistence may not be reflected by maintenance of specific antibody production by the host.

Concepts: Immune system, Bacteria, Lyme disease, Primate, Rhesus Macaque, Tick, Borrelia burgdorferi, Borrelia


Non-human primates currently serve as the best experimental model for Lyme disease due to their close genetic homology with humans and demonstration of all three phases of disease following infection with Borreliella (Borrelia) burgdorferi (Bb). We investigated the pathology associated with late disseminated Lyme disease (12 to 13 months following tick inoculation) in doxycycline-treated (28 days; 5mg/kg, oral, 2x/day) and untreated rhesus macaques (Rm). Minimal to moderate lymphoplasmacytic inflammation, with a predilection for perivascular spaces and collagenous tissues, was observed in multiple tissues including the cerebral leptomeninges, brainstem, peripheral nerves from both fore and hind limbs, stifle synovium and perisynovial adipose tissue, urinary bladder, skeletal muscle, myocardium, and visceral pericardium. Indirect immunofluorescence assays (IFA) combining monoclonal (outer surface protein A) and polyclonal antibodies were performed on all tissue sections containing inflammation. Rare morphologically intact spirochetes were observed in the brains of two treated Rm, the heart of one treated Rm, and adjacent to a peripheral nerve of an untreated animal. Borrelia antigen staining of probable spirochete cross-sections was also observed in heart, skeletal muscle, and near peripheral nerves of both treated and untreated animals. These findings support the notion that chronic Lyme disease symptoms can be attributable to residual inflammation in and around tissues that harbor a low burden of persistent host-adapted spirochetes and/or residual antigen.

Concepts: Antibody, Muscle, Lyme disease, Macaque, Primate, Rhesus Macaque, Borrelia burgdorferi, Borrelia