Infant Baboons Research Articles

Neonatal Hyperoxia Activates Activating Transcription Factor 4 to Stimulate Folate Metabolism and Alveolar Epithelial Type 2 Cell Proliferation.

Oxygen supplementation in preterm infants disrupts alveolar epithelial type 2 (AT2) cell proliferation through poorly understood mechanisms. Here, newborn mice are used to understand how hyperoxia stimulates an early aberrant wave of AT2 cell proliferation that occurs between Postnatal Days (PNDs) 0 and 4. RNA-sequencing analysis of AT2 cells isolated from PND4 mice revealed hyperoxia stimulates expression of mitochondrial-specific methylenetetrahydrofolate dehydrogenase 2 and other genes involved in mitochondrial one-carbon coupled folate metabolism and serine synthesis. The same genes are induced when AT2 cells normally proliferate on PND7 and when they proliferate in response to the mitogen fibroblast growth factor 7. However, hyperoxia selectively stimulated their expression via the stress-responsive activating transcription factor 4 (ATF4). Administration of the mitochondrial superoxide scavenger mitoTEMPO during hyperoxia suppressed ATF4 and thus early AT2 cell proliferation, but it had no effect on normative AT2 cell proliferation seen on PND7. Because ATF4 and methylenetetrahydrofolate dehydrogenase are detected in hyperplastic AT2 cells of preterm infant humans and baboons with bronchopulmonary dysplasia, dampening mitochondrial oxidative stress and ATF4 activation may provide new opportunities for controlling excess AT2 cell proliferation in neonatal lung disease.

Cardiac Xenotransplantation: Rebirth Amidst an Uncertain Future

The 1912 Nobel prize in Medicine and Physiology was given to Alexis Carrel for his work on the anastomosis of blood vessels, which formed the basis for organ transplantation. It is claimed he prophesied that “the ideal method would be to transplant in man organs of animals easy to secure and operate on, such as hogs, for instance. But it would in all probability be necessary to immunize organs of the hog against the human serum.”1 In 1964, James Hardy transplanted a chimpanzee heart into a human with only minutes of survival because the xenograft was too small to provide adequate hemodynamic support, and in 1984, Leonard Bailey transplanted an infant baboon heart into neonate Baby Fae, a milestone that lasted 21 days.

Development of bipedal walking in olive baboons, Papio anubis: A kinematic analysis.

Although extant nonhuman primates are not habitual bipeds, they are able to walk bipedally from an early age. In humans, children improve their walking skills through developmental processes and learning experience. In nonhuman primates, infants do not routinely experience bipedalism and their musculoskeletal system gradually specializes for other locomotor modes. The aim of this study is to explore the development of occasional bipedal walking in olive baboon and to test whether the postural adjustments change with age. We collected kinematics and spatiotemporal parameters of bipedal gait in an ontogenetic sample of 24 baboons. Data were collected at the primatology station of the CNRS (France) and a total of 47 bipedal strides were extracted for the present analysis. Adults and adolescents walk bipedally in the same way, and the average kinematic pattern is similar across the age-classes. Infants walk bipedally with longer duty factor, they present larger movement amplitude of the thigh and the amplitude of the knee joint decreases with speed. In contrast, older baboons increase the amplitude of the knee and ankle joints with speed. In a non-adapted biped, the postural adjustments of bipedal walking vary with age. In infant baboons, the balance requirements are likely to be higher and these are solved by adopting a "blocking strategy". In older baboons, the postural adjustments are focused on the lower limb and the movements increase with speed. These results may echo, in some respects, the developmental sequence of the intersegmental coordination described in the ontogeny of human locomotion.

Intranasal and intrapulmonary vaccination with an M protein-deficient respiratory syncytial virus (RSV) vaccine improves clinical signs and reduces viral replication in infant baboons after an RSV challenge infection

Respiratory syncytial virus (RSV) is the major viral respiratory pathogen for human infants and children. Despite a severe global burden incurred by annual RSV epidemics, there is no licensed RSV vaccine. We have developed an RSV vaccine from a human RSV strain from which the gene for the viral M protein has been deleted (“Mnull RSV”). RSV infects airway cells and produces each of its proteins. The M protein is responsible for reassembling the various other synthesized viral proteins into new, intact virus. In the absence of the M protein, therefore, reassembly does not occur, and the Mnull RSV does not replicate.We vaccinated 2-week old infant baboons with Mnull RSV either intranasally (IN) or directly into the lung (intratracheal, or IT), then infected these animals by inoculating human RSV directly into the lung. IN vaccination induced inconsistent serum RSV neutralizing antibody (NA) responses, but provided moderate reductions in respiratory rates, overall signs of illness and viral replication in bronchoalveolar lavage (BAL) fluid following infection. Intratracheal vaccination induced much stronger RSV NA responses, which persisted for at least 4–6 months. Following RSV infection, animals vaccinated by the IT route had much greater reductions in tachypnea and work of breathing than animals vaccinated IN, and had undetectable amounts of virus in BAL fluids. These results support the further development of IT Mnull RSV vaccination to reduce the impact of RSV infection in humans.

Successful experimental infant baboon model for childhood cryptosporidiosis studies

BackgroundCryptosporidiosis causes high morbidity and mortality in children under 2 years of age globally. The lack of an appropriate animal model that mimics the pathogenesis of disease in humans has hampered the development and testing of potential therapeutic options. This study aimed to develop and validate an infant baboon infection model of cryptosporidiosis.MethodsEighteen immunocompetent weaned infant baboons aged 12 to 16 months were used. The animals were n = 3 controls and three experimental groups of n = 5 animals each inoculated with Cryptosporidium parvum oocysts as follows: group 1: 2 × 104, group 2: 2 × 105, group 3: 2 × 106 followed by daily fecal sampling for oocyst evaluation. Blood sampling for immunological assay was done on the day of infection and weekly thereafter until the end of the experiment, followed by necropsy and histopathology. Statistical analysis was performed using R, SPSS, and GraphPad Prism software. Analysis of variance (ANOVA) and Bonferroni post hoc tests were used for comparison of the means, with p < 0.05 considered as a significant difference. Correlation coefficient and probit analysis were also performed.ResultsIn all experimental animals but not controls, the onset of oocyst shedding occurred between days 2 and 4, with the highest oocyst shedding occurring between days 6 and 28. Histological analysis revealed parasite establishment only in infected animals. Levels of cytokines (TNF-α, IFN-γ, and IL-10) increased significantly in experimental groups compared to controls.ConclusionFor developing a reproducible infant baboon model, 2 × 104 oocysts were an effective minimum quantifiable experimental infection dose.Graphic abstract

Developmental transitions in body color in chacma baboon infants: Implications to estimate age and developmental pace

In many primates, one of the most noticeable morphological developmental traits is the transition from natal fur and skin color to adult coloration. Studying the chronology and average age at such color transitions can be an easy and noninvasive method to (a) estimate the age of infants whose dates of birth were not observed, and (b) detect interindividual differences in the pace of development for infants with known birth dates. Using a combination of photographs and field observations from 73 infant chacma baboons (Papio ursinus) of known ages, we (a) scored the skin color of six different body parts from pink to gray, as well as the color of the fur from black to gray; (b) validated our method of age estimation using photographic and field observations on an independent subset of 22 infants with known date of birth; and (c) investigated ecological, social, and individual determinants of age-related variation in skin and fur color. Our results show that transitions in skin color can be used to age infant chacma baboons less than 7 months old with accuracy (median number of days between actual and estimated age = 10, range = 0-86). We also reveal that food availability during the mother's pregnancy, but not during lactation, affects infant color-for-age and therefore acts as a predictor of developmental pace. This study highlights the potential of monitoring within- and between-infant variation in color to estimate age when age is unknown, and developmental pace when age is known.

Bringing up baby: Maternal responsiveness, secondary attachments, and the development of infant social competence in wild olive baboons (Papio anubis).

Caregiver responsiveness and presence of secondary attachments play a crucial role in children's socio-cognitive and emotional development, but little is known of their effect on the development of non-human primates. Here we present the results of a 16-month behavioral study conducted on 22 wild infant olive baboons (Papio anubis) at the Uaso Ngiro Baboon Project, Kenya. This is the first study to examine the effects of maternal responsiveness and secondary attachments on the development of infant social behavior in a wild primate species that does not breed cooperatively. The data track maternal responsiveness and the rates of two behavioral indicators of infant social competence-orienting toward interactions and social play-over the course of the first year of life. Maternal responsiveness decreased as infants grew older, while infant orientation toward interactions and play behavior increased. Infants with poorly responsive mothers were more likely to have secondary attachments, and infants with secondary attachments to siblings oriented more frequently to social interactions than those with secondary attachments to adult/subadult males or with no secondary attachments. These findings indicate that variation in maternal responsiveness and presence of secondary attachments can influence the development of social competence in olive baboon infants.

Baboon bearing resemblance in pigmentation pattern to Siamese cat carries a missense mutation in the tyrosinase gene.

An infant hamadryas baboon exhibiting an albino phenotype-white body hair and red eyes-was born to parents with wild-type body color. Pigmentation on some parts of its body surfaced during childhood and progressed with age. This baboon in adulthood has gray hair on parts of its body, such as the tail, distal portion of the legs, and face, with the remainder being white. This pigmentation pattern resembles that of the Siamese cat and the Himalayan variants of the mouse and the mink. The distinguishing phenotypes in these animals are known to be caused by a temperature-sensitive activity of tyrosinase, an enzyme essential for biosynthesis of melanin. We sequenced all the five exons of the tyrosinase (TYR) gene of this albino baboon, which were amplified by PCR, and found a base substitution leading to alteration of the 365th amino acid from Ala to Thr. Tyrosinase requires copper as a cofactor for its enzyme function. It has two copper-binding sites, the second of which contains His residues in positions 363 and 367 that are critical to its function. Thus, p.(Ala365Thr) due to a mutation in the TYR gene is a likely candidate for the cause of the albino phenotype in this baboon.

2770. Intrapulmonary Vaccination with an M Protein-Deficient Respiratory Syncytial Virus (RSV) Vaccine Protects Infant Baboons Against an RSV Challenge

BackgroundRSV infection is a major cause of lung disease in infants, yet there is no licensed vaccine. We are developing a live RSV vaccine with a deletion of the M protein (“Mnull RSV”). The RSV M protein is responsible for assembling newly synthesized RSV proteins into intact virus. Mnull RSV infects cells, replicates all proteins except M, and incites antibody and T-cell responses but, in the absence of the M protein, cannot replicate and infect other cells. We wished to show that vaccination with Mnull RSV directly into the lung in early infancy induces persistent neutralizing antibody (NA) responses that protect infant baboons against an RSV challenge.MethodsTwo-week-old infants were vaccinated with a single dose of Mnull RSV (8 × 107 vaccine units) or a sham preparation instilled into an endotracheal tube. Infants were observed continuously for signs of rapid breathing using infrared cameras. Four to six months later, serum RSV NA titers were determined, and infants were challenged intratracheally with the human RSV A2 strain. Respiratory rates were calculated daily. On days 0, 5, 7, and 12 after infection, arterial blood was drawn for blood gas analysis, lung function was assessed using a pneumotachometer, and bronchoalveolar lavage was performed for virus titrations.ResultsAt 4–6 months following vaccination, RSV NA was present at a mean titer of 192 in sera of Mull RSV recipients, but was undetectable in sera of sham vaccinated animals. Animals were then challenged with RSV, and sham vaccinated animals developed increased respiratory rates, increased alveolar-arterial (A-a) oxygen gradients, and BAL viral titers on day 5 were 3,500 pfu/mL. In contrast, Mnull RSV vaccinated animals had lower respiratory ratios throughout the length of the study (P = 0.038), lesser A-a gradients (improved oxygenation) vs. controls, and no virus was recovered from BAL fluids (P < 0.0001).ConclusionIntrapulmonary vaccination of infantswith Mnull RSV at 2 weeks of age results in strong RSV NA responses that persist beyond the length of an average RSV season. Mnull RSV recipients were protected against tachypnea, reduced oxygenation and viral replication for at least 4–6 months following vaccination. We will next study intrapulmonary vaccination administering Mnull RSV via a nebulizer.Disclosures All authors: No reported disclosures.

Maternal Vaccination With a Monocomponent Pertussis Toxoid Vaccine Is Sufficient to Protect Infants in a Baboon Model of Whooping Cough.

Bordetella pertussis is a human pathogen responsible for serious respiratory illness. The disease is most severe in infants too young to be vaccinated with most hospitalizations and deaths occurring within this age group. The Advisory Committee on Immunization Practices recommended immunization of pregnant women to protect infants from birth until their first vaccination at 6-8 weeks of age. We previously demonstrated that maternal vaccination with licensed acellular pertussis vaccines protected newborn baboons from disease. We hypothesized that protection was due to toxin-neutralizing, maternal anti-pertussis toxin antibodies and predicted that maternal vaccination with a pertussis toxoid (PTx)-only vaccine would protect newborns from disease. Infant baboons born to unvaccinated mothers or mothers vaccinated with a PTx-only vaccine were challenged with B. pertussis at 5 weeks of age and followed for infection and signs of disease. Although all challenged infants were heavily colonized, the infant baboons born to mothers vaccinated with PTx-only vaccine were free from clinical disease following exposure to B. pertussis. In contrast, disease was observed in infants born to unvaccinated mothers. Our results demonstrated that maternal vaccination with a PTx-only vaccine is sufficient to protect newborn baboons from disease following exposure to pertussis.

M Protein-Deficient Respiratory Syncytial Virus (RSV) Vaccine Protects Infant Baboons Against RSV Challenge

BackgroundRSV bronchiolitis is the most common cause of hospitalization of infants in the US, and may lead to the development of long-term airway disease. Inactivated vaccines may lead to enhanced disease, while replicating vaccines have caused unacceptable degrees of illness, and may revert back to wild type. We developed an RSV vaccine lacking the gene for the M protein (Mnull RSV). The M protein is responsible for reassembly of the virus after it infects cells and expresses its proteins. Infant baboons vaccinated intranasally (IN) with Mnull RSV develop serum neutralizing antibody (NA) responses, but the virus does not replicate.Methods2-week-old baboons (n = 12) were primed IN with 107 vaccine units of Mnull RSV or a control preparation, and a similar booster dose was given 4 weeks later. Mnull RSV vaccination did not cause tachypnea, airway inflammation or other signs of illness when compared with sham-vaccinated controls. Two weeks after boosting, all infants were challenged intratracheally with human RSV A2. We continuously monitored respiratory rates and levels of overall activity. On various days following challenge, we obtained BAL fluids for leukocyte counts and degree of virus replication, and evaluated alveolar-arterial oxygen gradients (A-a O2).ResultsVaccinated animals (vs. unvaccinated controls) had lower respiratory rates (P = 0.0014), improved A-a O2 (P = 0.0063) and reduced viral replication (P = 0.0014). Activity scores were higher in vaccine recipients than in unvaccinated animals. Vaccine recipients also were primed for earlier serum and secretory neutralizing antibody responses, and greater airway lymphocyte responses. Airway lymphocyte numbers (but not antibody responses) were associated with lower respiratory rates and reduced viral replication (P < 0.01).ConclusionVaccination intranasally with Mnull RSV protected infant baboons against an RSV challenge without causing respiratory disease or enhanced illness, and is a promising candidate for use in human infants. Lymphocyte responses to vaccination may play an equal or greater role in protection against RSV infection than antibody responses.Disclosures All authors: No reported disclosures.

Maternal Pertussis Vaccination with a Mono-component Pertussis Toxoid Vaccine is Sufficient to Protect Newborns

Abstract Bordetella pertussis is a highly infectious human pathogen causing serious illness in infants, children and adults. The first pertussis vaccination is administered at two months of age, therefore, infants under two months of age are most vulnerable to infection. Rising incidence of pertussis resulted in the 2012 recommendation by the Advisory Committee on Immunization Practices (ACIP) to immunize all pregnant women to protect infants from birth until their first vaccination. Using a baboon model, we demonstrated that maternal vaccination with the three or four component acellular pertussis vaccines protected newborn baboons from the disease but not from the colonization. We hypothesized this protection was due to the transfer of maternal anti-PT antibodies to the infant. Therefore we evaluated the protection conferred by maternal vaccination with a pertussis toxoid (PTx) only vaccine. Infant baboons born to mothers vaccinated with the PTx-only vaccine were free from disease and had low WBC counts following exposure to B. pertussis at five weeks of age. In contrast, infants born to unvaccinated mothers experienced severe disease with high WBC counts. Our results demonstrate that vaccination of baboons during pregnancy with a PTx-only vaccine is sufficient to protect newborn baboons from disease following exposure to pertussis. Because pertussis toxin is a secreted protein that can be purified from bacterial supernatants, a single-component vaccine comprised of pertussis toxoid is very likely the most cost-effective acellular pertussis vaccine possible. The development and use of mono-component PTx vaccines may enable the extension of maternal vaccine programs to low and middle income countries.

The Challenge of Survival for Wild Infant Baboons

The Challenge of Survival for Wild Infant Baboons

Importance of (antibody-dependent) complement-mediated serum killing in protection against Bordetella pertussis

Pertussis is a highly contagious respiratory disease that is caused by Bordetella pertussis. Despite being vaccine preventable, pertussis rates have been rising steadily over the last decades, even in areas with high vaccine uptake. Recently, experiments with infant baboons indicated that although vaccination with acellular pertussis vaccines prevented disease, no apparent effect was observed on infection and transmission. One explanation may be that current acellular pertussis vaccines do not induce high levels of opsonophagocytic and/or bactericidal activity, implying that engineering of vaccines that promote bacterial killing may improve efficacy. Here, we discuss the importance of complement-mediated killing in vaccine-induced protection against B. pertussis. We first examine how B. pertussis may have evolved different complement evasion strategies. Second, we explore the benefits of opsonophagocytic and/or bactericidal killing in vaccine-induced protection and discuss whether or not inclusion of new opsonophagocytic or bactericidal target antigens in pertussis vaccines may benefit efficacy.

Biphasic response of checkpoint control proteins in hyperoxia: exposure to lower levels of oxygen induces genome maintenance genes in experimental baboon BPD.

Breathing high concentrations of oxygen (hyperoxia) causes lung injury and is associated with lung diseases such as bronchopulmonary dysplasia (BPD), respiratory distress syndrome and persistent pulmonary hypertension of the newborns. Hyperoxia (95-100%O2) causes DNA damage and growth arrest of lung cells and consequently cells die by apoptosis or necrosis. Although supplemental oxygen therapy is clinically important, the level and duration of hyperoxic exposure that would allow lung cells to reenter the cell cycle remains unclear. We hypothesized that cells exposed to lower concentrations of hyperoxia will retain the capacity to enter cell cycle when recovered in room air. We employed varying concentrations of oxygen (21-95%) to determine the response of lung cells to hyperoxia. Our results indicate that cells were growth arrested and failed to reenter the cell cycle when exposed to greater than 60% oxygen. Cell cycle checkpoint proteins were increased in a biphasic manner, increasing until 70% oxygen, but declined in greater than 90% oxygen. Microarray analysis shows that there is significant decrease in the abundance of Cdks 6-8 and retinoblastoma protein (Rb), p107 and p130 in exposure to 90% oxygen for 48h. We further tested the effect of clinically relevant as needed oxygen [(pro-re-nata (prn)] in premature infant (125-days and 140-days) baboon model of BPD. The microarray results show that 6 or 14d PRN oxygen-exposed animals had induced expression of chromosomal maintenance genes (MCMs), genes related to anti-inflammation, proliferation, and differentiation.

Pertussis Pathogenesis--What We Know and What We Don't Know

Pertussis is a worldwide public health threat. Bordetella pertussis produces multiple virulence factors that have been studied individually, and many have recently been found to have additional biological activities. Nevertheless, how they interact to cause the disease pertussis remains unknown. New animal models, particularly the infection of infant baboons with B. pertussis, are enabling longstanding questions about pertussis pathogenesis to be answered and new ones to be asked. Enhancing our understanding of pathogenesis will enable new approaches to the prevention and control of pertussis.

Maternal and Neonatal Vaccination Protects Newborn Baboons From Pertussis Infection

The United States is experiencing a pertussis resurgence that resulted in a 60-year high of 48 000 cases in 2012. The majority of hospitalizations and deaths occur in infants too young to be vaccinated. Neonatal and maternal vaccination have been proposed to protect newborns until the first vaccination, currently recommended at 2 months of age. These interventions result in elevated anti-Bordetella pertussis titers, but there have been no studies demonstrating that these measures confer protection. Baboons were vaccinated with acellular pertussis vaccine at 2 days of age or at 2 and 28 days of age. To model maternal vaccination, adult female baboons primed with acellular pertussis vaccine were boosted in the third trimester of pregnancy. Neonatally vaccinated infants, infants born to vaccinated mothers, and naive infants born to unvaccinated mothers were infected with B. pertussis at 5 weeks of age. Naive infant baboons developed severe disease when challenged with B. pertussis at 5 weeks of age. Baboons receiving acellular pertussis vaccine and infants born to mothers vaccinated at the beginning of their third trimester were protected. Our results demonstrate that neonatal vaccination and maternal vaccination confer protection in the baboon model and support further study of these strategies for protection of newborns from pertussis.

The Limits of the Pertussis Vaccine

Despite high immunization rates with pertussis vaccines, clinical cases of pertussis have resurged in the United States. In the 1990s, acellular pertussis (aP) vaccines replaced whole-cell pertussis (wP) vaccines because of toxicity concerns. To assess whether the increase in pertussis cases is related to relatively lower efficacy of aP vaccines, FDA researchers compared infant baboons who had been immunized using either an aP and or a wP vaccine (at 2, …

Infant baboons infected with respiratory syncytial virus develop clinical and pathological changes that parallel those of human infants

Respiratory syncytial virus (RSV) infection of the lower respiratory tract is the leading cause of respiratory failure among infants in the United States of America and annually results in >300,000 deaths worldwide. Despite the importance of RSV, there is no licensed vaccine, and no specific form of therapy. This is largely due to the absence of an appropriate animal model for the evaluation of vaccines and therapeutic agents. We inoculated anesthetized infant (4 wk) baboons (Papio anubis) with a human strain of RSV intranasally or intratracheally. Baboons were monitored daily for clinical changes. Anesthetized baboons were intubated at various intervals, and bronchoalveolar lavage (BAL) was performed for viral culture and determination of leukocyte counts. Sham-infected baboons served as controls. Necropsies were performed on infected baboons on days 1, 3, 5, 8, or 13 after inoculation, with pathological analysis and immunohistochemical staining of lung tissues to detect RSV antigen. Infected baboons developed tachypnea and reduced oxygenation peaking from 4 to 8 days after infection and persisting for ≥14 days. Virus was recoverable in BAL fluid up to 8 days following infection. Necropsy revealed intense interstitial pneumonia, sloughing of the bronchiolar epithelium, and obstruction of the bronchiolar lumen with inflammatory cells and sloughed epithelial cells. RSV antigen was identified in bronchiolar and alveolar epithelium. We conclude that RSV-infected infant baboons develop clinical and pathological changes that parallel those observed in human infants with RSV infection. The infant baboon represents a much-needed model for studying the pathogenesis of RSV infection and evaluating antivirals and vaccines.

First evidence of population-level oro-facial asymmetries during the production of distress calls by macaque (Macaca mulatta) and baboon (Papio anubis) infants

Infant distress calls are vocal communicative signals present in most animals. In nonhuman primates, they correspond to critical vocalizations for caregiving and contribute to the socio-emotional development of the individual. To our knowledge, no systematic study on the development of oro-facial hemispheric specialization in nonhuman primates infants is available. Thus, we proposed to assess to what extend emotional behaviors underlying distress calls in macaques and in baboons younger than 1 year of age may express lateralization. For the first time, a population-level cerebral lateralization was found for screaming and cooing calls in macaques and for the moaning call in baboons. However, differences in patterns of lateralization were found between the two vocalizations produced by macaques (for cooing, the left-side of the mouth opened widest than the right one and for screaming, a preference toward the right side of the mouth was noticed) as well as a sex effect for cooing. Our findings are discussed within the comparative literature in order to comprehend the ontogenetic and phylogenetic changes of hemispheric specialization for emotions in the primate order.