Factors influencing the success of male introductions into groups of female rhesus macaques: Introduction technique, male characteristics and female behavior.

In captive populations of rhesus macaques, novel adult males are commonly introduced to female groups every few years to prevent inbreeding, which mimics male dispersal in wild macaque populations. However, introducing adult males is challenging because macaques are aggressive to newcomers, which can result in serious injuries. Efforts to reduce trauma risk during the introduction process and increase the probability of success are needed. Here we investigate the impact of multiple factors, including male attributes (e.g., age, weight, rank, and experience), introduction method (punctuated vs. continual exposure to females), and female behavior, on males' trauma risk and integration success. We studied eight introductions of multimale cohorts (3-7 males each; N = 36 total) into existing female groups of rhesus macaques at the Yerkes National Primate Research Center. Four cohorts were introduced using the punctuated exposure method where adult males were moved each morning from run housing to the females' indoor enclosure and returned to run housing in the afternoon, and four cohorts were introduced using the continual exposure method where adult males were moved to an introduction enclosure attached to the females' outdoor compound, allowing males to live in protected contact next to the female group continuously. Generalized linear mixed models fitted to trauma risk (e.g., latency to first trauma; total trauma count) and success or failure to integrate (i.e., continual residence within the female group for greater than 53% of days within a 28-day window after first overnight stay) showed that continual exposure to females in the introduction enclosure reduced male trauma risk and increased the likelihood of successful integration compared to punctuated exposure. Males received less trauma when they received a higher rate of grooming from females. Male attributes had no effect. These findings highlight the importance of introduction technique and female behavior in the process of males' social integration into female groups.

Use of Introduction Enclosures to Integrate Multimale Cohorts into Groups of Female Rhesus Macaques (Macaca mulatta).

Integrating animals into a new group is a challenge for both free-ranging and captive adult male rhesus monkeys (Macaca mulatta), and for females in groups receiving new males. To ensure the genetic viability of the population, however, male transfers must occur in both natural and captive settings. To facilitate the introduction of groups of adult males to adult females, we designed a new enclosure that is attached to the outdoor compound where females are housed. Here we describe the construction of 3 introduction enclosures, their use during 4 introductions of groups of adult males to adult females, a brief comparison of introduction success rates associated with the new introduction enclosures with those of our traditional male introduction method, and a critique by the various groups of staff members working with the new enclosures. Overall, the introduction enclosures benefitted both the macaques and the facility personnel and appear to be a useful enhancement to our process of integrating breeding groups.

Utility of Automated Feeding Data to Detect Social Instability in a Captive Breeding Colony of Rhesus Macaques (Macaca mulatta): A Case Study of Intrafamily Aggression.

Some captive breeding colonies of rhesus macaques live in large outdoor multimale, multifemale social groups. These groups are composed of several matrilineal families, governed by a clear female dominance hierarchy. Aggression within the same or between different matrilineal families due to social instability can result in trauma and mortality. Therefore, a primary management goal is to detect emerging social unrest before the onset of significant fighting and wounding. Accordingly, groups are monitored routinely for changes in dominance and alliance relations as well as for increases in trauma frequency and severity. Decreased food intake is a normal physiologic response to acute stress; therefore, inappetence in key animals or groups of monkeys might be used as an indicator of increased social stress and emerging instability. An incident of intrafamily aggression occurred recently in a breeding group at our facility and resulted in considerable fighting. Because this compound was equipped with an automated feeding system that tracks the caloric intake of individual animals, we retrospectively analyzed feeding data to determine whether significant reduction in caloric consumption occurred prior to the onset of aggression, compared with baseline values. Neither the entire group nor individual families showed any significant differences in total caloric intake between baseline and previous 24 h values; however, the affected family exhibited a 20% reduction in total caloric during the 24 h prior to the aggression. Most notably, the deposed subfamily showed a marked 58% reduction in caloric intake during the prior 24 h, whereas remaining subfamilies showed no significant changes in intake. High-ranking animals of the group, including the α female, ß female, and α male, similarly exhibited marked decreases in caloric intake during that period. These findings indicate that automated feeders can assist management staff with monitoring social stability in breeding colonies of rhesus macaque.

Effect of Chronic Social Stress on Prenatal Transfer of Antitetanus Immunity in Captive Breeding Rhesus Macaques (Macaca mulatta).

Because tetanus can cause significant morbidity and mortality in NHP, colonywide vaccination with tetanus toxoid is recommended for outdoor breeding colonies of rhesus macaques, with primary immunizations commonly given to infants at 6 mo of age followed by booster vaccines every 10 y. Maternal antibodies are thought to offer protective immunity to infants younger than 6 mo. However, historical colony data from the Yerkes National Primate Research Center show a higher incidence of tetanus among infants (≤ 6 mo old) born to subordinate dams. Whether this higher incidence of infantile tetanus is due to a higher incidence of trauma among subordinate animals or is a stress-induced impairment of maternal antibody protection is unknown. Studies in other NHP species suggest that chronic exposure to social stressors interferes with the receptor-mediated transplacental transfer of IgG. Therefore, the primary aim of this study was to determine whether chronic stress associated with social subordination impairs prenatal transfer of antitetanus immunity in breeding female rhesus macaques. Subjects included 26 high- and 26 low-ranking adult female rhesus macaques that were nearly 5 or 10 y after their initial immunization and their nonimmunized infants. We hypothesized that infants born to subordinate dams that were nearly 10 y after immunization would have the lowest infant-to-dam antibody ratios and thus would be at greatest risk for infection. Results revealed no significant intergroup differences in infant antitetanus IgG levels. However, infant-to-dam IgG ratios against tetanus were significantly lower among subordinate animals compared with dominant macaques, after accounting for the number of years since the dam's initial vaccination. In addition, higher maternal hair cortisol levels predicted lower infantto-dam tetanus toxoid IgG ratios. Together, these findings suggest that chronic social stress in female rhesus macaques may hamper the prenatal transfer of antitetanus immunity to offspring.

Trauma rates and patterns in specific pathogen free (SPF) rhesus macaque (Macaca mulatta) groups.

There are some predictable patterns of trauma in captive rhesus macaque (Macaca mulatta) social groups. Several factors have been documented to contribute to these patterns, including group formation of unrelated animals, and the establishment of dominance ranks. Here, we report on how socially induced trauma in groups of rhesus monkeys is influenced by the breeding season, numbers of matrilines per group and matriline size. We analyzed 3 years of data collected from veterinary admittance logs for four groups in our specific pathogen free (SPF) breeding colony. Since the groups differed in time from formation, both the numbers of matrilines and the composition of those matrilines were different. Across the four groups, trauma rates were significantly higher during the fall breeding season than the spring and summer months when births occur. The group that was formed most recently, comprised of the greatest number of matrilines but fewest related animals, showed significantly higher rates of trauma than the older social groups. Further, the middle and lowest ranking families received signifincantly higher rates of trauma than the highest ranking families, suggesting a rank-related phenomenon. Additionally, there was a significant negative correlation between numbers of adult females in a matriline and rates of trauma observed in each matriline, but the numbers of adult females are significantly higher in the top ranked families compared to all of the other matrilines. These findings suggest that trauma rates increase during the breeding season and may be exacerbated in recently formed breeding groups that have smaller matrilines and reduced opportunities for social support to mitigate rank-related aggression. Management practices should be devised to ensure adequate matrilineal size to decrease rates of trauma in captive rhesus macaque groups.

Early adolescent Depo-Provera exposure increases stillbirths in adult sooty mangabeys.

The 3-month injectable contraceptive medroxyprogesterone acetate (MPA; Depo-Provera) is a synthetic progestin that protects against pregnancy by suppressing ovulation. Studies have focused on the resumption of ovulation after MPA-treatment cessation but neglected potential long-term effects of MPA exposure on future successful reproduction. MPA is frequently administered to adolescent girls; however, long-term fertility effects of adolescent MPA exposure have not been explored. We investigated fertility after extended MPA exposure in a species of old world primate, the sooty mangabey (Cercocebus atys). Female sooty mangabeys (n=31) received chronic MPA-treatment for 4-8 years. At MPA-treatment onset, subjects were either parous adults (n=14) or nulliparous adolescents (n=17), with adolescent-treated subjects being further divided into those who had reached first ovulation (n=10) and those who had not (n=7). After MPA-treatment cessation, adolescent-treated females had a significantly higher incidence of stillbirth than did age-matched and parity-matched controls, whereas adult-treated females did not differ from their matched controls. Females placed on MPA-treatment prior to first ovulation had a significantly higher incidence of stillbirth post-treatment than did females placed on MPA-treatment after first ovulation. Diabetic females had an increased incidence of stillbirth as compared to nondiabetic females; however, when controlling for diabetes, MPA exposure prior to first ovulation was still a significant positive predictor of stillbirth. These findings suggest that the post-treatment fertility effects of chronic MPA exposure vary with the developmental timing of treatment onset and raise concern about the use of MPA as a contraceptive for adolescent girls.

Target cell availability, rather than breast milk factors, dictates mother-to-infant transmission of SIV in sooty mangabeys and rhesus macaques.

Mother-to-infant transmission (MTIT) of HIV is a serious global health concern, with over 300,000 children newly infected in 2011. SIV infection of rhesus macaques (RMs) results in similar rates of MTIT to that of HIV in humans. In contrast, SIV infection of sooty mangabeys (SMs) rarely results in MTIT. The mechanisms underlying protection from MTIT in SMs are unknown. In this study we tested the hypotheses that breast milk factors and/or target cell availability dictate the rate of MTIT in RMs (transmitters) and SMs (non-transmitters). We measured viral loads (cell-free and cell-associated), levels of immune mediators, and the ability to inhibit SIV infection in vitro in milk obtained from lactating RMs and SMs. In addition, we assessed the levels of target cells (CD4+CCR5+ T cells) in gastrointestinal and lymphoid tissues, including those relevant to breastfeeding transmission, as well as peripheral blood from uninfected RM and SM infants. We found that frequently-transmitting RMs did not have higher levels of cell-free or cell-associated viral loads in milk compared to rarely-transmitting SMs. Milk from both RMs and SMs moderately inhibited in vitro SIV infection, and presence of the examined immune mediators in these two species did not readily explain the differential rates of transmission. Importantly, we found that the percentage of CD4+CCR5+ T cells was significantly lower in all tissues in infant SMs as compared to infant RMs despite robust levels of CD4+ T cell proliferation in both species. The difference between the frequently-transmitting RMs and rarely-transmitting SMs was most pronounced in CD4+ memory T cells in the spleen, jejunum, and colon as well as in central and effector memory CD4+ T cells in the peripheral blood. We propose that limited availability of SIV target cells in infant SMs represents a key evolutionary adaptation to reduce the risk of MTIT in SIV-infected SMs.

Increased stability and limited proliferation of CD4+ central memory T cells differentiate nonprogressive simian immunodeficiency virus (SIV) infection of sooty mangabeys from progressive SIV infection of rhesus macaques.

UNLABELLED: Depletion of CD4(+) central memory T (TCM) cells dictates the tempo of progression to AIDS in simian immunodeficiency virus (SIV)-infected rhesus macaques (RMs) both in the natural history of infection and in the context of vaccination. CD4(+) TCM cells of sooty mangabeys (SMs), a natural host for SIV in which infection is nonpathogenic, are less susceptible to SIV infection than CD4(+) TCM cells of RMs. Whether this relative protection from infection translates into increased stability of CD4(+) TCM cells in natural versus nonnatural hosts has not yet been determined. Here we compared, both cross-sectionally and longitudinally, the levels of CD4(+) TCM cells in a large cohort of SMs and RMs and the association between CD4(+) TCM levels and the main virologic and immunologic markers of disease progression. Consistent with their lower susceptibility to infection, CD4(+) TCM cells of SIV-infected SMs are lost with kinetics 20 times slower than those of SIV-infected RMs. Remarkably, the estimated length of time of SIV infection needed for CD4(+) TCM cells to fall to half of their initial levels is <16 months for RMs but >17 years for SMs. Furthermore, the fraction of proliferating CD4(+) TCM cells is significantly lower in SIV-infected SMs than in SIV-infected RMs, and the extent of CD4(+) TCM cell proliferation is associated positively with CD4(+) T cell levels in SIV-infected SMs but negatively with CD4(+) T cell levels in SIV-infected RMs. Collectively, these findings identify increased stability and maintenance of the prohomeostatic role of CD4(+) TCM cells as features distinguishing nonprogressive from progressive SIV infections and support the hypothesis of a direct mechanistic link between the loss of CD4(+) TCM cells and disease progression. IMPORTANCE: Comparison of the immunologic effects of simian immunodeficiency virus (SIV) infection on rhesus macaques (RMs), a species characterized by progression to AIDS, and natural host sooty mangabeys (SMs), a species which remains AIDS free, has become a useful tool for identifying mechanisms of human immunodeficiency virus (HIV) disease progression. One such distinguishing feature is that CD4(+) central memory T (TCM) cells in SIV-infected SMs are less infected than the same cells in RMs. Here we investigated whether lower levels of infection in SMs translate into a better-preserved CD4(+) TCM compartment. We found that the CD4(+) TCM compartment is significantly more stable in SIV-infected SMs. Likely to compensate for this cell loss, we also found that CD4(+) TCM cells increase their level of proliferation upon SIV infection in RMs but not in SMs, which mechanistically supports their preferential infectivity. Our study provides new insights into the importance of long-term maintenance of CD4(+) TCM homeostasis during HIV/SIV infection.

Mother-to-infant transmission of simian immunodeficiency virus is rare in sooty mangabeys and is associated with low viremia.

Mother-to-child transmission of human immunodeficiency virus type 1 (HIV-1) occurs in utero, intrapartum, and through breastfeeding, with a cumulative rate of transmission of 35 to 40%. As a result, ∼ 400,000 children become infected each year. Little is known about mother-to-infant transmission (MTIT) during natural simian immunodeficiency virus (SIV) infection of sooty mangabeys (SMs) that typically is nonpathogenic despite high viral loads. In this study, we retrospectively investigated the rates of MTIT in a large colony of naturally SIV-infected SMs using serological (anti-SIV antibody by enzyme-linked immunosorbent assay [ELISA] and Western blot analysis) and virological (SIV(smm) real-time reverse transcription-PCR) methods. We examined 161 SM infants born to SIV-infected mothers and found that 150 (93.2%) were infected by non-MTIT (n = 120) or remained uninfected (n = 30). The remaining 11 SM infants (6.8%) were defined as acquiring SIV by presumptive MTIT based on (i) the presence of anti-SIV antibodies without seroreversion and (ii) a viral load of >500 copies/ml of serum in the first year of life. SM infants infected with SIV by presumptive MTIT did not show any increased morbidity or mortality, indicating that the infection is nonpathogenic even when acquired early in life. Interestingly, viral loads of SIV-infected SM infants with presumptive MTIT were 2-log lower than those of SIV-infected adult SMs living in the same colony (i.e., ∼ 1,000 and 100,000 copies/ml, respectively). These results indicate that MTIT is substantially less frequent in naturally SIV-infected SMs than in HIV-1-infected humans and results in nonpathogenic infection associated with low SIV viremia. Evolutionary pressure to reduce MTIT may have contributed to the restriction of SIV pathogenesis in natural hosts.

A five-year longitudinal analysis of sooty mangabeys naturally infected with simian immunodeficiency virus reveals a slow but progressive decline in CD4+ T-cell count whose magnitude is not predicted by viral load or immune activation.

Natural simian immunodeficiency virus (SIV) infection in sooty mangabeys (SMs) typically does not result in AIDS, despite high-level viremia and significant depletion of mucosal CD4(+) T cells. Here, we report the results of the first longitudinal study of a large cohort of SMs naturally infected with SIV (n = 78) housed at the Yerkes National Primate Research Center from which samples were obtained three times over a 5-year period. In this study, we observed (i) no signs of simian AIDS, (ii) stable SIV loads, (iii) a slow but progressive decline in CD4(+) T-cell counts (from a mean of 1,067.0 cells/mm(3) at time point 1 to 764.8 cells/mm(3) at time point 3) and increases in the numbers of animals with CD4(+) T-cell levels below 500 and 200 cells/mm(3) (from 8 to 28 of 78 and from 1 to 4 of 78, respectively), (iv) progressive declines in percentages of naïve CD4(+) and CD8(+) T cells (from 37.7 to 24.8% and from 21.0 to 13.0%, respectively), and (v) stably low levels of activated/proliferating T cells as well as CD4(+) CCR5(+) T cells. Since the level of total CD4(+) T cells and the fraction of naïve T cells in SIV-uninfected SMs also declined, it is possible that some of these observations are related to aging, as the SIV-infected animals were significantly older than the uninfected animals. In contrast to the decline in CD4(+) T cell counts in individuals infected with human immunodeficiency virus (HIV), the decline in CD4(+) T cell counts in SMs naturally infected with SIV over a 5-year period was not predicted by either plasma viremia or levels of T-cell activation. Taken together, these results confirm that natural SIV infection is nonprogressive from a clinical, virological, and immunological point of view and that stable levels of viremia associated with persistently low-level immune activation represent key differences from the natural course of HIV infection in humans.

Comparison of carbetocin and oxytocin for the prevention of postpartum hemorrhage following vaginal delivery:a double-blind randomized trial.

OBJECTIVES: To compare the efficacy of a single 100 micro g intramuscular (IM) carbetocin injection, a long-acting oxytocin agonist, to a 2-hour 10 IU oxytocin intravenous (IV) infusion, in reducing the incidence and severity of postpartum hemorrhage (PPH) in women at risk for this condition. METHODS: A randomized, double-blind, placebo-controlled study was conducted at 2 hospital centres, including 160 women with at least 1 risk factor for PPH. Eighty-three women received 100 microg carbetocin IM and an IV placebo immediately after placental delivery, while 77 women received placebo IM and oxytocin IV infusion. Complete blood count was collected at entry and 24 hours postpartum. All outcome measures, including the need for additional uterotonic agents or uterine massage, blood loss, and drop in hemoglobin and hematocrit, were analyzed using chi-square, Fisher exact, and Student t tests. RESULTS: Population profile and risk factors for PPH were similar for each group. No significant difference was observed in the number of women requiring additional uterotonic medication (12 in each group). However, in the carbetocin group, 36 of the 83 women (43.4%) required at least 1 uterine massage compared to 48 of the 77 women (62.3%) in the oxytocin group (P <.02). Overall, uterotonic intervention was clinically indicated in 37 of the women (44.6%) receiving carbetocin compared to 49 of the women (63.6%) given an IV oxytocin infusion (P <.02). There were no differences in laboratory PPH indicators between the 2 groups.

Immunomodulatory effects of estrogen and progesterone replacement in a nonhuman primate model.

A novel postmenopausal nonhuman primate model consisting of healthy young and old ovariectomized rhesus macaques was used to assess the short-term immunomodulatory effects of transdermally administered estrogen and progesterone. Specifically, we determined estrogen- and progesterone-induced changes in absolute numbers of circulating lymphocytes (B lymphocytes, CD4+ lymphocytes, and CD8+ lymphocytes) as well as lymphocytes expressing the activation markers CD25 and CD69. In addition, we assessed B and T lymphocyte activity, i.e, immunoglobulin (Ig) and interferon-gamma (IFN-gamma) production by peripheral blood mononuclear cells (PBMCs). In general, treatment with estrogen or progesterone resulted in decreased lymphocyte numbers and in down-modulation of activation markers. In addition, hormone replacement resulted in a decreasing trend for PBMC IFN-gamma production, whereas PBMC Ig production was minimally affected. Hormone treatment seemed to influence young and old animals differently, with the young animals appearing more susceptible to its immune system-related effects. These results indicate that, in our animal model exogenously administered hormones may dynamically interact with the immune system, resulting in in vivo modulation of lymphocyte numbers and activity.