Long trimer-immunization interval and appropriate adjuvant reduce immune responses to the soluble HIV-1-envelope trimer base.

Soluble 'SOSIP'-stabilized HIV-1 envelope glycoprotein (Env) trimers elicit dominant antibody responses targeting their glycan-free base regions, potentially diminishing neutralizing responses. Previously, using a nonhuman primate model, we demonstrated that priming with fusion peptide (FP)-carrier conjugate immunogens followed by boosting with Env trimers reduced the anti-base response. Further, we demonstrated that longer immunization intervals further reduced anti-base responses and increased neutralization breadth. Here, we demonstrate that long trimer-boosting intervals, but not long FP immunization intervals, reduce the anti-base response. Additionally, we identify that FP priming before trimer immunization enhances antibody avidity to the Env trimer. We also establish that adjuvants Matrix M and Adjuplex further reduce anti-base responses and increase neutralizing titers. FP priming, long trimer-immunization interval, and an appropriate adjuvant can thus reduce anti-base antibody responses and improve Env-directed vaccine outcomes.

Structure-based design of a single-chain triple-disulfide-stabilized fusion-glycoprotein trimer that elicits high-titer neutralizing responses against human metapneumovirus.

The Pneumoviridae family of viruses includes human metapneumovirus (HMPV) and respiratory syncytial virus (RSV). The closely related Paramyxoviridae family includes parainfluenza viruses (PIVs). These three viral pathogens cause acute respiratory tract infections with substantial disease burden in the young, the elderly, and the immune-compromised. While promising subunit vaccines are being developed with prefusion-stabilized forms of the fusion glycoproteins (Fs) of RSV and PIVs, for which neutralizing titers elicited by the prefusion (pre-F) conformation of F are much higher than for the postfusion (post-F) conformation, with HMPV, pre-F and post-F immunogens described thus far elicit similar neutralizing responses, and it has been unclear which conformation, pre-F or post-F, would be the most effective HMPV F-vaccine immunogen. Here, we investigate the impact of further stabilizing HMPV F in the pre-F state. We replaced the furin-cleavage site with a flexible linker, creating a single chain F that yielded increased amounts of pre-F stabilized trimers, enabling the generation and assessment of F trimers stabilized by multiple disulfide bonds. Introduced prolines could increase both expression yields and antigenic recognition by the pre-F specific antibody, MPE8. The cryo-EM structure of a triple disulfide-stabilized pre-F trimer with the variable region of antibody MPE8 at 3.25-Å resolution confirmed the formation of designed disulfides and provided structural details on the MPE8 interface. Immunogenicity assessments in naïve mice showed the triple disulfide-stabilized pre-F trimer could elicit high titer neutralization, >10-fold higher than elicited by post-F. Immunogenicity assessments in pre-exposed rhesus macaques showed the triple disulfide-stabilized pre-F could recall high neutralizing titers after a single immunization, with little discrimination in the recall response between pre-F and post-F immunogens. However, the triple disulfide-stabilized pre-F adsorbed HMPV-directed responses from commercially available pooled human immunoglobulin more fully than post-F. Collectively, these results suggest single-chain triple disulfide-stabilized pre-F trimers to be promising HMPV-vaccine antigens.

Anti-viral efficacy of a next-generation CD4-binding site bNAb in SHIV-infected animals in the absence of anti-drug antibody responses.

Broadly neutralizing antibodies (bNAbs) against HIV-1 are promising immunotherapeutic agents for treatment of HIV-1 infection. bNAbs can be administered to SHIV-infected rhesus macaques to assess their anti-viral efficacy; however, their delivery into macaques often leads to rapid formation of anti-drug antibody (ADA) responses limiting such assessment. Here, we depleted B cells in five SHIV-infected rhesus macaques by pretreatment with a depleting anti-CD20 antibody prior to bNAb infusions to reduce ADA. Peripheral B cells were depleted following anti-CD20 infusions and remained depleted for at least 9 weeks after the 1st anti-CD20 infusion. Plasma viremia dropped by more than 100-fold in viremic animals after the initial bNAb treatment. No significant humoral ADA responses were detected for as long as B cells remained depleted. Our results indicate that transient B cell depletion successfully inhibited emergence of ADA and improved the assessment of anti-viral efficacy of a bNAb in a SHIV-infected rhesus macaque model.

Differential relationships between chronic hormone profiles in pregnancy and maternal investment in rhesus monkey mothers with hair loss in the neonatal period.

Hair loss is commonly used as an indicator of well being in primate facilities, yet it has been shown to also occur in otherwise healthy pregnant and postpartum females. There is significant variability in the incidence of hair loss during these important developmental periods, reasons for which remain unclear. We studied female rhesus monkeys (Macaca mulatta, n = 47) with and without hair loss in pregnancy/postpartum. We hypothesized that, similar to previously published reports, pregnancy would result in an increased likelihood of hair loss, and that hair loss would be correlated with higher hair cortisol concentrations (HCCs). We further hypothesized that hair loss among pregnant females is related to differential maternal investment. We studied a subset of monkeys (n = 26) from mid-to-late pregnancy through peak lactation, some of which exhibited hair loss in the perinatal period (n = 15), and some of which did not (n = 11). We examined fetal measurements, infant birth weight, infant growth rate, and milk yield volume (MYV) in the first 30 days as indices of investment. We found that pregnant monkeys showed a greater incidence of hair loss across the study year (χ2(2) = 6.55, P = 0.038), and that mothers with hair loss had significantly higher HCCs in pregnancy than those without (F(2,28) = 3.8, P = 0.017, ηp2 = 0.21). HCCs in pregnancy were correlated with severity of hair loss in the neonatal period (r(37) = 0.42, P = 0.008). Moreover, HCCs in pregnancy were positively correlated with infant birth weight (r(12) = 0.56, P = 0.038), infant growth rate (r(12) = 0.64, P = 0.014), and MYV (r(11) = 0.85, P < 0.001) for alopecic but not non-alopecic mothers. These mothers did not differ in fetal measurements, infant birth weight/growth rate, or MYV. Our results suggest that hair loss in some monkeys, especially during the birthing season, may be a signal of greater physiological stress during pregnancy and differential investment by mothers to their offspring. Am. J. Primatol. 79:e22489, 2017. © 2015 Wiley Periodicals, Inc.

Genetic diversity of Klebsiella pneumoniae isolates during an outbreak in a non-human primate research colony.

BACKGROUND: Klebsiella pneumoniae can be a serious pathogen in non-human primates, particularly Neotropical monkeys. METHODS: During a K. pneumoniae outbreak in an owl monkey research colony, 13 K. pneumoniae isolates were DNA fingerprinted by automated repetitive extragenic palindromic-polymerase chain reaction and the profiles compared to isolates obtained from other non-human primate species during the same time period and isolates from previous outbreaks. RESULTS: Eleven different types of K. pneumoniae were circulating in the owl monkey colony at the time of the outbreak. When comparing owl monkey isolates relatedness to previous colony outbreak isolates and squirrel monkey and capuchin monkey isolates, all were different. CONCLUSIONS: These results agree with recent reports where K. pneumoniae nosocomial isolates in hospital settings can have high genetic diversity, and multiple strains can be circulating simultaneously. This potential genetic diversity should be considered when designing strategies for controlling K. pneumoniae outbreaks in captive non-human primate colonies.

Mitochondrial compromise in 3-year old patas monkeys exposed in utero to human-equivalent antiretroviral therapies.

Antiretroviral (ARV) drug therapy, given during pregnancy for prevention of mother-to-child transmission of human immunodeficiency virus 1 (HIV-1), induces fetal mitochondrial dysfunction in some children. However, the persistence/reversibility of that dysfunction is unclear. Here we have followed Erythrocebus patas (patas) monkey offspring for up to 3 years of age (similar in development to a 15-year old human) after exposure of the dams to human-equivalent in utero ARV exposure protocols. Pregnant patas dams (3-5/exposure group) were given ARV drug combinations that included zidovudine (AZT)/lamivudine (3TC)/abacavir (ABC), or AZT/3TC/nevirapine (NVP), for the last 10 weeks (50%) of gestation. Infants kept for 1 and 3 years also received drug for the first 6 weeks of life. In offpsring at birth, 1 and 3 years of age mitochondrial morphology, examined by electron microscopy (EM), was compromised compared to the unexposed controls. Mitochondrial DNA (mtDNA), measured by hybrid capture chemiluminescence assay (HCCA) was depleted in hearts of patas exposed to AZT/3TC/NVP at all ages (P < 0.05), but not in those exposed to AZT/3TC/ABC at any age. Compared to unexposed controls, mitochondrial reserve capacity oxygen consumption rate (OCR by Seahorse) in cultured bone marrow mesenchymal fibroblasts from 3-year-old patas offspring was ∼50% reduced in AZT/3TC/ABC-exposed patas (P < 0.01), but not in AZT/3TC/NVP-exposed patas. Overall the data show that 3-year-old patas sustain persistent mitochondrial dysfunction as a result of perinatal ARV drug exposure. Environ. Mol. Mutagen. 57:526-534, 2016. © 2016 Wiley Periodicals, Inc.

Reproductive consequences of a matrilineal overthrow in rhesus monkeys.

Matrilineal overthrows in macaque societies are rare but devastating events, often resulting in severe morbidity, mortality, and loss of individual and group fitness. The handful of documented macaque overthrows provides scant evidence to reveal the severity or longevity of reproductive consequences resulting from such violent events. We analyzed archival records from semi-free ranging rhesus monkeys, Macaca mulatta, across 6 years (55 ≤ N ≤ 107, from 2007 to 2012) during which time a matrilineal overthrow occurred (in 2009) to test the hypothesis that extremely violent interactions such as a matrilineal overthrow would significantly reduce reproductive fitness for the involved matrilines and for the troop collectively. The matrilineal overthrow resulted in a significant increase in infant loss for the population from the previous year (χ(2) = 8.117, df = 1, P = 0.004), as evidenced by the fact that in 2009, but not in other years, the proportion of infants lost was greater than the proportion of viable infants (χ(2) = 4.55, df = 1, P = 0.03). Moreover, the deposed matriline suffered 100% infant loss in 2009, a significant change from the previous year (χ(2) = 7.87, df = 1, P = 0.005) while the attacking matriline suffered 50% infant loss (also a significant change from the previous year; χ(2) = 4.44, df = 1, P = 0.035), with the uninvolved, lowest-ranking matriline showing no change in infant loss from the previous year (χ(2) = 0.008, df = 1, P = 0.93). The deposed matriline did not produce viable offspring again until 3 years later. We further found that rates of severe fighting (as indicated by the number of fight wounds requiring medical treatment) were positively correlated with infant loss across the 6 years of the study (r[s] = 0.943, P = 0.005). Our data indicate that extreme periods of intra-group conflict, such as the matrilineal overthrow, have marked short-term consequences for individual fitness, and may be extreme examples of the long-term influences that group violence exerts on the mean fitness within a primate troop.

Tamoxifen-DNA adduct formation in monkey and human reproductive organs.

The estrogen analog tamoxifen (TAM), used for adjuvant therapy of breast cancer, induces endometrial and uterine tumors in breast cancer patients. Proliferation stimulus of the uterine endometrium is likely involved in tumor induction, but genotoxicity may also play a role. Formation of TAM-DNA adducts in human tissues has been reported but remains controversial. To address this issue, we examined TAM-DNA adducts in uteri from two species of monkeys, Erythrocebus patas (patas) and Macaca fascicularis (macaque), and in human endometrium and myometrium. Monkeys were given 3-4 months of chronic TAM dosing scaled to be equivalent to the daily human dose. In the uteri, livers and brains from the patas (n = 3), and endometrium from the macaques (n = 4), TAM-DNA adducts were measurable by TAM-DNA chemiluminescence immunoassay. Average TAM-DNA adduct values for the patas uteri (23 adducts/10(8) nucleotides) were similar to those found in endometrium of the macaques (19 adducts/10(8) nucleotides). Endometrium of macaques exposed to both TAM and low-dose estradiol (n = 5) averaged 34 adducts/10(8) nucleotides. To examine TAM-DNA persistence in the patas, females (n = 3) were exposed to TAM for 3 months and to no drug for an additional month, resulting in low or non-detectable TAM-DNA in livers and uteri. Human endometrial and myometrial samples from women receiving (n = 8) and not receiving (n = 8) TAM therapy were also evaluated. Women receiving TAM therapy averaged 10.3 TAM-DNA adducts/10(8) nucleotides, whereas unexposed women showed no detectable TAM-DNA. The data indicate that genotoxicity, in addition to estrogen agonist effects, may contribute to TAM-induced human endometrial cancer.

The influence of age on serum concentrations of cardiac troponin I: results in rats, monkeys, and commercial sera.

Cardiac troponins serve as serum biomarkers of myocardial injury. The current study examined the influence of age on serum concentrations of cardiac troponin I (cTnI). An ultrasensitive immunoassay was used to monitor cTnI concentrations in Sprague-Dawley (SD) rats and Erythrocebus patas monkeys of different ages. The mean cTnI concentrations were highest in 10-day-old rats compared to 25-, 40-, and 80-day-old SD rats. Cardiomyocyte remodeling was apparent in hearts from 10-day-old SD rats as evident by hypercellularity, irregularly shaped nuclei, and moderate numbers of myocytes undergoing mitosis and apoptosis. The mean concentration of cTnI in 5 newborn monkeys was considerably higher than that of three 1-year-old monkeys. Evidence of cardiomyocyte remodeling was also observed in these newborn hearts (loss of myofibrils and cytoplasmic vacuolation). Commercial animal serum samples were also analyzed. The concentrations of cTnI detected in fetal equine and porcine serum were considerably higher than that found in adult equine and porcine serum samples Likewise, fetal bovine serum had higher cTnI concentrations (>2,400 pg/ml) than did adult caprine and laprine samples (2.5-2.7 pg/ml). The present study found age-related differences in cTnI concentrations, with higher levels occurring at younger ages. This effect was consistent across several animal species.

Perinatal exposure of patas monkeys to antiretroviral nucleoside reverse-transcriptase inhibitors induces genotoxicity persistent for up to 3 years of age.

BACKGROUND: Erythrocebus patas (patas) monkeys were used to model antiretroviral (ARV) drug in human immunodeficiency virus type 1-infected pregnant women. METHODS: Pregnant patas dams were given human-equivalent doses of ARVs daily during 50% of gestation. Mesenchymal cells, cultured from bone marrow of patas offspring obtained at birth and at 1 and 3 years of age, were examined for genotoxicity, including centrosomal amplification, micronuclei, and micronuclei containing whole chromosomes. RESULTS: Compared with controls, statistically significant increases (P < .05) in centrosomal amplification, micronuclei, and micronuclei containing whole chromosomes were found in mesenchymal cells from most groups of offspring at the 3 time points. CONCLUSIONS: Transplacental nucleoside reverse-transcriptase inhibitor exposures induced fetal genotoxicity that was persistent for 3 years.

FACIAL ASYMMETRY IS NEGATIVELY RELATED TO CONDITION IN FEMALE MACAQUE MONKEYS.

The face is an important visual trait in social communication across many species. In evolutionary terms there are large and obvious selective advantages in detecting healthy partners, both in terms of avoiding individuals with poor health to minimise contagion and in mating with individuals with high health to help ensure healthy offspring. Many models of sexual selection suggest that an individual's phenotype provides cues to their quality. Fluctuating asymmetry is a trait that is proposed to be an honest indicator of quality and previous studies have demonstrated that rhesus monkeys gaze longer at symmetric faces, suggesting preferences for such faces. The current study examined the relationship between measured facial symmetry and measures of health in a captive population of female rhesus macaque monkeys. We measured asymmetry from landmarks marked on front-on facial photographs and computed measures of health based on veterinary health and condition ratings, number of minor and major wounds sustained, and gain in weight over the first four years of life. Analysis revealed that facial asymmetry was negatively related to condition related health measures, with symmetric individuals being healthier than more asymmetric individuals. Facial asymmetry appears to be an honest indicator of health in rhesus macaques and asymmetry may then be used by conspecifics in mate-choice situations. More broadly, our data support the notion that faces are valuable sources of information in non-human primates and that sexual selection based on facial information is potentially important across the primate lineage.

The effect of gonadectomy on prepulse inhibition and fear-potentiated startle in adolescent rhesus macaques.

Sex steroids, such as testosterone, can regulate brain development, cognition and modify psychiatric conditions. However, the role of adolescent testosterone in the emergence of cognitive deficits relevant to psychiatric illness has not been directly studied in primates. We examined whether removing testosterone during adolescence in rhesus macaques would affect prepulse inhibition (PPI) and fear-potentiated startle (FPS), which are translational tests of cognition affected in psychiatric disorders. Prepubertal macaques (30 months old) were castrated (n=6) or sham operated (n=6), and PPI and (FPS) were tested before the onset of puberty (34 months old) and after the pubertal surge in sex hormones 16 months later (50 months old). As expected there were no differences between the gonadectomized and intact groups' level of startle amplitude, PPI or (FPS) before puberty. After puberty, the intact group displayed substantially less PPI than the gonadectomized group, consistent with evidence that PPI is attenuated by endogenous increases in sex hormones. At the end of the study, testosterone among the intact monkeys was also correlated with tyrosine hydroxylase levels in the putamen, suggesting the attenuation of PPI by gonadal sex hormones may be influenced by subcortical dopamine. Thus, puberty involves significant increases in sex hormones, which in turn may modulate subcortical dopamine synthesis and affect cognitive functions impaired in psychiatric illnesses such as schizophrenia.

Gonadectomy negatively impacts social behavior of adolescent male primates.

Social behavior changes dramatically during primate adolescence. However, the extent to which testosterone and other gonadal hormones are necessary for adolescent social behavioral development is unknown. In this study, we determined that gonadectomy significantly impairs social dominance in naturalistic settings and changes reactions to social stimuli in experimental settings. Rhesus macaques were castrated (n= 6) or sham operated (n=6) at age 2.4 years, group-housed for 2 years, and ethograms were collected weekly. During adolescence the gonadally intact monkeys displayed a decrease in subordinate behaviors and an increase in dominant behaviors, which ultimately related to a rise in social status and rank in the dominance hierarchy. We measured monkey's reactions to emotional faces (fear, threat, neutral) of conspecifics of three ages (adult, peer, infant). Intact monkeys were faster to retrieve a treat in front of a threatening or infant face, while castrated monkeys did not show a differential response to different emotional faces or ages. No group difference in reaction to an innate fear-eliciting object (snake) was found. Approach and proximity responses to familiar vs unfamiliar conspecifics were tested, and intact monkeys spent more time proximal to a novel conspecific as compared to castrates who tended to spend more time with a familiar conspecific. No group differences in time spent with novel or familiar objects were found. Thus, gonadectomy resulted in the emergence of significantly different responses to social stimuli, but not non-social stimuli. Our work suggests that intact gonads, which are needed to produce adolescent increases in circulating testosterone, impact social behavior during adolescences in primates.

Successful behavioral strategy to unite mother and infant rhesus monkeys (Macaca mulatta) after cesarean delivery.

Developmental studies of pre- to postnatal continuities in rhesus monkeys sometimes require infants be reared with their mothers. However, complications during pregnancy or experimental designs may require cesarean delivery. Owing to lack of published information on this subject, strategies are needed to introduce mothers to their infants following cesarean delivery. Using positive and negative reinforcement techniques we attempted to unite six infant rhesus macaques, Macaca mulatta, to their mothers following c-sections. For our seventh subject, we attempted to cross-foster an infant onto an unrelated female after she had undergone a cesarean surgery for a late-term spontaneous abortion. The mothers varied in age, parity, previous postnatal mothering experience with infants, housing earlier to delivery, and housing subsequent to introduction. Although there were large individual differences among the mother-infant pairs, all seven introductions were successful. The mothers learned to accept and care for their infants from the continuous application of operant conditioning techniques. These data suggest that mother-rearing following cesarean section is a realistic possibility whether required for clinical reasons or for proper experimental control. Furthermore, the ability to successfully mother-rear infants produced from cesarean delivery lessens the impact this potential confound of not being reared by their mothers exerts on many types of developmental studies.