Improving transparency-A call to include social housing information in biomedical research articles involving nonhuman primates

The social setting of animal subjects in the research environment has known effects on a variety of dependent measures used in biomedical research. Proper evaluation of the robustness of published research is dependent upon transparent, detailed, and accurate reporting of research methods, including the animals' social housing conditions. However, to date, most research articles utilizing nonhuman primates (NHPs) provide only partial data on this topic, hampering transparency, and reproducibility. Therefore, we call for the inclusion of information pertaining to the social aspects of the animals' housing conditions in publications involving NHPs to improve transparency. We argue that including this information in scientific publications is crucial for the interpretation of research findings in the appropriate context and for understanding unexplained variability in study findings. Finally, the inclusion of this information in publications will additionally familiarize scientists with how other researchers conducting similar studies are housing their animals and will encourage them to consider the implications of various housing conditions on their research outcomes.

Training rhesus macaques to take daily oral antiretroviral therapy for preclinical evaluation of HIV prevention and treatment strategies

Background

Macaque models of simian or simian/human immunodeficiency virus (SIV or SHIV) infection are critical for the evaluation of antiretroviral (ARV)-based HIV treatment and prevention strategies. However, modelling human oral ARV administration is logistically challenging and fraught by limited adherence. Here, we developed a protocol for administering daily oral doses of ARVs to macaques with a high rate of compliance.

Methods

Parameters of positive reinforcement training (PRT), behavioral responses and optimal drug delivery foods were defined in 7 male rhesus macaques (Macaca mulatta). Animals were trained to sit in a specified cage location prior to receiving ARVs, emtricitabine (FTC) and tenofovir alafenamide (TAF), in a blended food mixture, which was followed immediately with a juice chaser. Consistency of daily oral adherence was evaluated in 4 trained macaques receiving clinically equivalent doses of FTC and TAF (20 and 1.5 mg/kg, respectively) in a short-term (1 month) and an extended (6 month) trial. Adherence was monitored using medication diaries and by quantifying intracellular FTC-triphosphate (FTC-TP) and tenofovir-diphosphate (TFV-DP) concentrations in peripheral mononuclear blood cells (PBMCs).

Results

Trained macaques quickly and consistently took daily oral ARVs for 1 month with an average 99.8% observed adherence. Intracellular concentrations of TFV-DP (median = 845.8 fmol/million cells [range, 620.8–1031.3]) and FTC-TP (median = 367.0 fmol/million cells [range, 289.5–413.5) in PBMCs were consistent with high adherence. Extended treatment with select subjects yielded similar observations for three months (99.5% adherence, 352/356 complete doses taken), although a sudden drop in adherence was observed after splenic biopsy surgery.

Conclusions

We demonstrate that trained macaques reliably adhere to a daily oral ARV regimen, although unexpected adherence issues are possible. Our approach, using clinical doses of oral FTC and TAF daily, further refines macaque models of HIV treatment and prevention by mimicking the human route and timing of ARV administration.

The effects of repeated automated plasmapheresis in goats (Capra hircus) in response to vaccination with purified influenza hemagglutinin proteins

Seasonal influenza is a contagious respiratory illness that annually affects millions of people worldwide. To identify currently circulating influenza virus subtypes, the Centers for Disease Control and Prevention's International Reagent Resource distributes the World Health Organization (WHO) influenza reagent kits, which are used globally by testing laboratories for influenza surveillance. The data generated by the kits aid in strain selection for the influenza vaccine each season. The use of animals to produce high quality and quantities of antibodies is critical to the production of these kits. In this study, we assessed the effects and efficacy of repeated sampling from automated plasmapheresis in goats. Analysis of blood samples demonstrated that repeated automated plasmapheresis procedures did not adversely affect the immediate or long-term health of goats. Further, our results indicate that repeated plasmapheresis in goats was capable of generating 2 liters of antibody-rich plasma per goat per week. This volume is sufficient to produce enough WHO influenza kits to conduct over 1 million tests. Thus, we have shown that the rapid production of plasma in goats can positively impact the public health preparedness and response to influenza.

Pair housing of Vervets/African Green Monkeys for biomedical research

Vervets, also known as African green monkeys, are a nonhuman primate species widely used in biomedical research. However, there are currently few references available describing techniques and rates of success for pair-housing this species. We present data from four cohorts of vervets from three different facilities: (i) the Wake Forest Vervet Research Colony (VRC; n = 72 female pairs, n= 52 male pairs), (ii) the University of Louisiana at Lafayette-New Iberia Research Center (UL-NIRC; n = 57 female pairs, n = 54 male pairs), (iii) the Tulane National Primate Research Center (TNRPC; n = 18 male pairs), and (iv) a cohort of imported males (n = 18 pairs) at Wake Forest. Compatibility was measured at 14, 30, and 60 days following introduction. Success rates for pair-housing at 14 days ranged from 96% to 98% for females and 96% to 100% for males at the VRC and UL-NIRC but were lower in the smaller imported male cohorts (TNPRC: 50%; WF: 28%). Among the UL-NIRC cohort and VRC male cohort, most of the pair separations after 14 days were due to reasons unrelated to social incompatibility. In contrast, a large proportion of TNPRC and imported male pairs successful at 14 days required separation within 60 days due to incompatibility. Multiple logistic regressions were performed using cohort, mean age of pair and weight difference between pair-mates as potential predictors of compatibility at 14 days. All three predicted the 14-day outcome in males but not females. A separate analysis in the VRC cohort found no evidence that prior familiarity in a group setting influenced outcomes. Variations in success rates across cohorts may have been influenced by introduction methodology. Behavioral differences between vervets and macaques, coupled with our findings, lead us to theorize that the gradual introduction techniques commonly implemented to pair house macaques may not be beneficial or suitable for this species. Am. J. Primatol. 79:e22501, 2017. © 2015 Wiley Periodicals, Inc.

Socialization of adult owl monkeys (Aotus sp.) in Captivity

Social housing has often been recommended as one-way to address the psychological well-being of captive non-human primates. Published reports have examined methods to socialize compatible animals by forming pairs or groups. Successful socialization rates vary depending on the species, gender, and environment. This study presents a retrospective look at pairing attempts in two species of owl monkeys, Aotus nancymaae and A. azarae, which live in monogamous pairs in the wild. The results of 477 pairing attempt conducted with captive, laboratory housed owl monkeys and 61 hr of behavioral observations are reported here. The greatest success pairing these owl monkeys occurred with opposite sex pairs, with an 82% success rate. Opposite sex pairs were more successful when females were older than males. Female-female pairs were more successful than male-male (MM) pairs (62% vs 40%). Successful pairs stayed together between 3 and 7 years before the animals were separated due to social incompatibility. Vigilance, eating, and sleeping during introductions significantly predicted success, as did the performance of the same behavior in both animals. The results of this analysis show that it is possible to give captive owl monkeys a social alternative even if species appropriate social partners (i.e., opposite sex partners) are not available. The focus of this report is a description of one potential way to enhance the welfare of a specific new world primate, the owl monkey, under laboratory conditions. More important is how the species typical social structure of owl monkeys in nature affects the captive management of this genus. Am. J. Primatol. 79:e22521, 2017. © 2015 Wiley Periodicals, Inc.

Comparison of carbon dioxide and argon euthanasia: effects on behavior, heart rate, and respiratory lesions in rats

In this study we compared rat (n = 16) responses to euthanasia with either gradual-fill CO(2) or rapid induction argon gas by evaluating the animals' heart rate via radiotelemetry, behavior, and vocalizations. We also evaluated the histologic effects of the gases. Rats were placed in an open test chamber 24 h before the start of the experiment. During baseline tests, rats were exposed to oxygen to evaluate the effects of the noise and movement of gas entering the chamber; 1 wk later, rats were euthanized by gas displacement with either 10%/min CO(2) or 50%/min argon gas. Rats tended to have higher heart rats and were more active during the baseline test, but these parameters were normal before the euthanasia experiment, suggesting that the rats had acclimated to the equipment. Heart rate, behavior, and ultrasonic vocalizations were recorded for 2 min after gas introduction in both groups. All rats appeared conscious throughout the test interval. The heart rates of rats exposed to argon did not change, whereas those of rats exposed to CO(2) declined significantly. Unlike those exposed to CO(2), rats euthanized with argon gas gasped and demonstrated seizure-like activity. There were no differences in the pulmonary lesions resulting from death by either gas. Our results suggest that argon as a sole euthanasia agent is aversive to rats. CO(2) using a 10%/min displacement may be less aversive than more rapid displacements. Future research investigating methods of euthanasia should allow sufficient time for the rats to acclimate to the test apparatus.

Survey of environmental enhancement programs for laboratory primates

Animal welfare regulations in the United States require that nonhuman primate environmental enhancement plans be made in accordance with currently accepted professional standards; however, little information is available for quantifying common practice. Here we report the results of a 2003 survey that was sent to individuals overseeing enrichment programs at a variety of primate research institutions. The surveys requested information on program administration and management, implementation standards, procedures, and constraints pertaining to major categories of environmental enrichment, as well as intervention plans for animals exhibiting behavioral pathologies. Data were obtained on the management of 35,863 primates in 22 facilities. Behavioral scientists performed program oversight at the majority of facilities. Most programs reported recent changes, most commonly due to external site visits, and least commonly resulting from internal review. Most facilities' institutional animal care and use committees (IACUCs) included of individuals with behavioral expertise, and about two-thirds reported that enrichment issues could influence research protocol design. While most primates were reported to be housed socially (73%), social housing for indoor-housed primates appears to have changed little over the past 10 years. Research protocol issues and social incompatibility were commonly cited constraints. Implementation of feeding, manipulanda, and structural enrichment was relatively unconstrained, and contributions to these aspects of behavioral management generally included individuals in a wide variety of positions within a facility. In contrast, enrichment devices were used on a less widespread basis within facilities, and positive reinforcement programs that involved dedicated trainers were rare. We suggest that altering the role of the IACUC would be a productive avenue for increasing the implementation of social housing, and that an emphasis on prevention rather than intervention against behavioral pathology is warranted. The data from this survey may be useful for anticipating future program evaluations, establishing more effective internal evaluations, and assessing program progress and resource allocation.

Balancing animal research with animal well-being: establishment of goals and harmonization of approaches

A resource is provided for the creation of an institutional program that balances the scientific mission of an institution with the well-being of the animals used in support of the research. The concept of harmonizing scientific goals with animal well-being was first suggested in the early part of the twentieth century and later revitalized in the literature of the 1950s. Harmonization can best be achieved through the promotion of a team initiative. The team should include, at a minimum, the scientist, veterinarian, institutional animal care and use committee, and animal care staff. It is the responsibility of this animal research team to promote and balance the generation of scientifically valid data with animal well-being. The team must strive to minimize or eliminate non-protocol variables that could adversely affect the validity and repeatability of the experimental data. Good experimental design coupled with excellent communication between team members can often minimize or eliminate many variables and result in both better science and animal well-being. To ensure the scientific validity of experimental data, scientists must be aware of the complex nature of the environment in which their animals are maintained. To ensure repeatablity of an experiment, scientists must document and publish both the inanimate and social environments in which their animals are housed. Better documentation of environmental variables and their correlation with experimental results will promote critical knowledge about the relationships between an animal's environment, its well-being, and science.

Treatment of persistent self-injurious behavior in rhesus monkeys through socialization: a preliminary report

This paper is a retrospective report describing outcomes for six male rhesus monkeys, each with a history of persistent self-injurious behavior (SIB), after their social introduction to female rhesus monkeys. Pairing procedures for five of the six male primates were implemented after surgical vasectomy. One male had previous pairing experience with a female prior to vasectomy resulting in an unplanned pregnancy. This male was re-socialized with his former female partner after surgery. The SIB-related medical histories of the males before and after the pairings are presented. One goal for promoting pair-housing of chronic SIB male monkeys with female monkeys was to determine whether this intervention would function to reduce or eliminate the expression of SIB and thus provide enhanced socialization opportunities for previously singly housed animals.

Locomotor activity in female rhesus monkeys: assessment of age and calorie restriction effects

As a component of a long-term, longitudinal study of aging in this primate model, the objective of the current experiment was to assess age and diet effects on locomotor activity in a cross-sectional analysis. By attaching a motion detection device to the home cage, locomotor activity was monitored over a week in a group (N = 47) of female rhesus monkeys (Macaca mulatta) 6-26 yrs of age. About half these monkeys composed a control group fed a nutritionally fortified diet near ad libitum levels, whereas an experimental group had been fed the same diet at levels 30% less than comparable control levels for approximately 5 yrs prior to testing. Among control monkeys, a marked age-related decline in activity was noted when total activity was considered and also when diurnal and nocturnal periods of activity were analyzed separately. When comparing activity levels between control and experimental groups, only one significant diet effect was noted, which was in the youngest group of monkeys (6-8 yrs of age) during the diurnal period. Monkeys in the experimental group exhibited reduced activity compared to controls. Body weight was not consistently correlated to activity levels. In some older groups, heavier monkeys tended to show greater activity, but in younger groups the opposite pattern was observed.

Activity measures in rhesus monkeys on long-term calorie restriction

Calorie restriction (CR), undernutrition without malnutrition, extends the mean and maximal lifespan of several ecologically diverse species. Rodents on CR demonstrate increased activity measured as spontaneous locomotion, wheel running, open field behavior or movement. Activity measures were recorded from 19 male rhesus monkeys (Macaca mulatta) as either controls (C) which were fed a nutritious diet to approximate ad libitum levels, or as experimentals (E) which were fed 30% less than age- and weight-matched controls. Within each diet group, some monkeys (n = 10) began CR at 2.3 years of age (range 2.2-2.4 yrs, J Group) while another group (n = 9) began CR at approximately 4.6 years of age (range 4-5.25, A group). Beginning about 6 years after initiation of the study, behavioral activity was measured via ultrasonic motion detectors and recorded on videotape. Diurnal and circadian activity was clearly discernible. Peaks in activity were associated with mealtime and colony husbandry. Compared to Group A, Group J monkeys exhibited higher overall activity as measured by sensors, and also significantly more circling. Compared to AC monkeys, group AE monkeys demonstrated higher rates of gross motor behavior, pacing, stereotypies and grooming. The increases in motor activity observed in one group of monkeys were consistent with results obtained from rodent studies of CR and aging. CR did not significantly inhibit or negatively influence the display of behavior of rhesus monkeys in the laboratory environment. We report here, for the first time, increases in activity due to CR in a model other than the rodent.

A Macintosh computer system for collecting and analyzing rodent sexual behavior

We present a Macintosh-based computer system for collection and analysis of rodent sexual behavior. Two computer programs are presented. The first is an entirely generalizable real time data collection program that records any keyboard or keypad inputs (e.g., user defined behavior codes) and their time of occurrence. The second is somewhat generalizable; we use it to analyze frequencies, durations, and latencies relative to a copulatory series (including mounts, intromissions, and ejaculations). To our knowledge, these are the first such programs available on the Macintosh platform.

Seasonal weight changes in male rhesus monkeys (Macaca mulatta)

Adult male rhesus monkeys lose weight during the breeding season and regain it during the nonbreeding season. The annual pattern of maximum weight gain just prior to the onset of breeding resembles the seasonal "fattening" seen in squirrel monkeys, but the period of weight gain is less discrete. The magnitude of weight change is less in younger males, in that sexually immature males gain weight in both seasons, but significantly less during the breeding season. Females do not lose weight during the breeding season. Post hoc analyses revealed no significant correlations between male testosterone levels, dominance ranks, weights, or weight changes. The heaviest animals as juveniles were predictably the heaviest as adolescents. The timing of seasonal changes in testosterone did not correlate with the timing of changes in weight; weight losses followed the rise in testosterone, and weight gains continued until early in the breeding season after testosterone levels had already begun to rise. It is suggested that seasonal hormonal changes may influence activities in individuals and that changes in the activities of particular group members may alter the activity patterns of other group members. This alteration of activity patterns due to group influences on individuals as well as individual influences on the group may explain why hormonal regulation of seasonal weight appears to be indirect and why individuals (juveniles) experiencing no seasonal hormonal changes nonetheless show differences in activity patterns and seasonal weight changes.