Benserazide racemate and enantiomers induce fetal globin gene expression in vivo: Studies to guide clinical development for beta thalassemia and sickle cell disease.

Increased expression of developmentally silenced fetal globin (HBG) reduces the clinical severity of ß-hemoglobinopathies. Benserazide has a relatively benign safety profile having been approved for 50 years in Europe and Canada for Parkinson's disease treatment. Benserazide was shown to activate HBG gene transcription in a high throughput screen, and subsequent studies confirmed fetal hemoglobin (HbF) induction in erythroid progenitors from hemoglobinopathy patients, transgenic mice containing the entire human ß-globin gene (ß-YAC) and anemic baboons. The goal of this study is to evaluate efficacies and plasma exposure profiles of benserazide racemate and its enantiomers to select the chemical form for clinical development. Intermittent treatment with all forms of benserazide in ß-YAC mice significantly increased proportions of red blood cells expressing HbF and HbF protein per cell with similar pharmacokinetic profiles and with no cytopenia. These data contribute to the regulatory justification for development of the benserazide racemate. Additionally, dose ranges and frequencies required for HbF induction using racemic benserazide were explored. Orally administered escalating doses of benserazide in an anemic baboon induced γ-globin mRNA up to 13-fold and establish an intermittent dose regimen for clinical studies as a therapeutic candidate for potential treatment of ß-hemoglobinopathies.

Translational Model of Zika Virus Disease in Baboons.

Zika virus (ZIKV) is an emerging mosquito-borne flavivirus with devastating outcomes seen recently in the Americas due to the association of maternal ZIKV infection with fetal microcephaly and other fetal malformations not previously associated with flavivirus infections. Here, we have developed the olive baboon (Papio anubis) as a nonhuman primate (NHP) translational model for the study of ZIKV pathogenesis and associated disease outcomes to contrast and compare with humans and other major NHPs, such as macaques. Following subcutaneous inoculation of adult male and nonpregnant female baboons, viremia was detected at 3 and 4 days postinfection (dpi) with the concordant presentation of a visible rash and conjunctivitis, similar to human ZIKV infection. Furthermore, virus was detected in the mucosa and cerebrospinal fluid. A robust ZIKV-specific IgM and IgG antibody response was also observed in all the animals. These data show striking similarity between humans and the olive baboon following infection with ZIKV, suggesting our model is a suitable translational NHP model to study ZIKV pathogenesis and potential therapeutics.IMPORTANCE ZIKV was first identified in 1947 in a sentinel rhesus monkey in Uganda and subsequently spread to Southeast Asia. Until 2007, only a small number of cases were reported, and ZIKV infection was relatively minor until the South Pacific and Brazilian outbreaks, where more severe outcomes were reported. Here, we present the baboon as a nonhuman primate model for contrast and comparison with other published animal models of ZIKV, such as the mouse and macaque species. Baboons breed year round and are not currently a primary nonhuman primate species used in biomedical research, making them more readily available for studies other than human immunodeficiency virus studies, which many macaque species are designated for. This, taken together with the similarities baboons have with humans, such as immunology, reproduction, genetics, and size, makes the baboon an attractive NHP model for ZIKV studies in comparison to other nonhuman primates.

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

Background: 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. Methods: 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. Results: 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. Conclusions: Our results demonstrated that maternal vaccination with a PTx-only vaccine is sufficient to protect newborn baboons from disease following exposure to pertussis.

Histopathology of Bordetella pertussis in the Baboon Model.

Pertussis is a severe respiratory disease caused by Bordetella pertussis The classic symptoms of pertussis include paroxysmal coughing with an inspiratory whoop, posttussive vomiting, cyanosis, and persistent coryzal symptoms. Infants under 2 months of age experience more severe disease, with most deaths occurring in this age group. Most of what is known about the pathology of pertussis in humans is from the evaluation of fatal human infant cases. The baboon model of pertussis provides the opportunity to evaluate the histopathology of severe but nonfatal pertussis. The baboon model recapitulates the characteristic clinical signs of pertussis observed in humans, including leukocytosis, paroxysmal coughing, mucus production, heavy colonization of the airway, and transmission of the bacteria between hosts. As in humans, baboons demonstrate age-related differences in clinical presentation, with younger animals experiencing more severe disease. We examined the histopathology of 5- to 6-week-old baboons, with the findings being similar to those reported for fatal human infant cases. In juvenile baboons, we found that the disease is highly inflammatory and concentrated to the lungs with signs of disease that would typically be diagnosed as acute respiratory distress syndrome (ARDS) and bronchopneumonia. In contrast, no significant pathology was observed in the trachea. Histopathological changes in the trachea were limited to cellular infiltrates and mucus production. Immunohistostaining revealed that the bacteria were localized to the surface of the ciliated epithelium in the conducting airways. Our observations provide important insights into the pathology of pertussis in typical, severe but nonfatal pertussis cases in a very relevant animal model.

Apnea induction for invasive lung function testing in infant olive baboons: Comparison of intravenous propofol versus hyperventilation.

BACKGROUND: In various types of pulmonary research, pulmonary function testing (PFT) is performed to quantify the severity of lung disease. Induction of apnea and positive pressure ventilation are required for accurate PFT measurements in non-cooperative subjects. We compared two methods of apnea induction in infant olive baboons (Papio anubis). METHODS: Pulmonary function testing results were compared during apnea induced by hyperventilation (CO2 washout) vs. intravenous propofol (1 dose 10 mg/kg). PFT was evaluated using a hot-wire pneumotachometer incorporated within an Avea ventilator in nine 1-month-old baboons. RESULTS: Propofol induced apnea faster and more reliably. In both groups, PFT values passed the statistical equivalence test and were not significantly different (Student's t-test). There was a trend toward less data variability after propofol administration. CONCLUSIONS: Intravenous propofol was non-inferior to CO2 washout for apnea induction in infant olive baboons. Propofol induced apnea faster and more reliably and yielded less variable PFT results.

Maternal and neonatal vaccination protects newborn baboons from pertussis infection.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Use of an Sm-p80-based therapeutic vaccine to kill established adult schistosome parasites in chronically infected baboons.

No vaccines are available for human use for any parasitic infections, including the helminthic disease schistosomiasis. Sm-p80, the large subunit of Schistosoma mansoni calpain, is a leading antigen candidate for a schistosomiasis vaccine. Prophylactic and antifecundity efficacies of Sm-p80 have been tested using a variety of vaccine approaches in both rodent and nonhuman primate models. However, the therapeutic efficacy of a Sm-p80-based vaccine had not been determined. In this study, we evaluated the therapeutic efficacy of Sm-p80 by using 2 different strategies and 3 Sm-p80-based vaccine formulations in baboons. Vaccine formulations were able to decrease established adult worms by 10%-36%, reduce retention of eggs in tissues by 10%-57%, and decrease egg excretion in feces by 13%-33%, compared with control formulations. Marked differences were observed in B and T cell immune correlates between vaccinated and control animals. This is the first report of killing of established adult schistosome worms by a vaccine. In addition to distinct prophylactic efficacy of Sm-p80, this study adds to the evidence that Sm-p80 is a potentially important antigen with both substantial prophylactic and therapeutic efficacies. These data reinforce that Sm-p80 should be moved forward along the path toward human clinical trials.

Are there advantages in the use of specific pathogen-free baboons in pig organ xenotransplantation models?

Baboons have natural antibodies against pig antigens. We have investigated whether there are differences in anti-non-Gal pig antibody levels between baboons maintained under specific pathogen-free (SPF) conditions and those housed under conventional conditions (non-SPF) that might be associated with improved outcome after pig-to-baboon organ transplantation. Baboons (n = 40) were housed indoors (SPF n = 8) or in indoor/outdoor pens (non-SPF n = 32) in colonies of similar size and structure. Non-SPF colonies harbor a number of pathogens common to non-human primate species, whereas many of these pathogens have been eliminated from the SPF colony. Complete blood cell counts (CBC), blood chemistry, and anti-non-Gal IgM and IgG levels were monitored. There were no significant differences in CBC or blood chemistry between SPF and non-SPF baboons. Anti-non-Gal IgM levels were significantly lower in the SPF baboons than in the non-SPF baboons (MFI 7.1 vs. 8.8, P < 0.05). One SPF and two non-SPF baboons had an MFI >20; if these three baboons are omitted, the mean MFIs were 4.8 (SPF) vs. 7.5 (non-SPF) (P < 0.05). Anti-non-Gal IgG was minimal in both groups (MFI 1.0 vs. 1.0). As their levels of anti-non-Gal IgM are lower, baboons maintained under SPF conditions may be beneficial for xenotransplantation studies as the initial binding of anti-pig IgM to an α1,3-galactosyltransferase gene-knockout pig organ may be less, thus resulting in less complement and/or endothelial cell activation. However, even under identical SPF conditions, an occasional baboon will express a high level of anti-non-Gal IgM, the reason for which remains uncertain.

Longevity of Sm-p80-specific antibody responses following vaccination with Sm-p80 vaccine in mice and baboons and transplacental transfer of Sm-p80-specific antibodies in a baboon.

Based on data obtained using vaccine efficacy studies in mice, hamsters, and baboons, the credentials of Sm-p80 as a first tier vaccine candidate for schistosomiasis have been well established. Sm-p80-based vaccine formulation(s) have consistently exhibited potent prophylactic efficacy in reducing adult worm burden following cercarial challenge and induce killing of established adult worms in chronic infection. This vaccine is protective against both intestinal and urinary schistosomiasis. In this study, the longevity of Sm-p80-specific antibody responses was studied in mice and in baboons. Robust antibody titers were detected in mice for up to 60 weeks following vaccination with Sm-p80 recombinant vaccine (Sm-p80 + GLA-SE). In the follow-up experiments to our published studies, Sm-p80-specific IgG was also detected in baboons 5-8 years following the initial vaccination with an Sm-p80 DNA vaccine. In one baboon, transfer of Sm-p80-specific antibody was detected in umbilical cord blood and in the baby. These long-lasting humoral immune response data coupled with the vaccine efficacy data in rodents and nonhuman primates further strengthens the case for Sm-p80 to be moved forward through development leading to human clinical trials.

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.

Establishing a swine model to compare vascular prostheses in a contaminated field.

OBJECTIVE: Patch arteriotomies are performed during many vascular procedures. Whereas synthetic materials are generally felt to be inappropriate for infected environments, the suitability of glutaraldehyde-treated bovine pericardium (GBP), a biologic material, in such instances is unknown. Our main objectives were to develop an animal model to study vascular prostheses while comparing the infectability of polyester (Dacron) and GBP in a topically infected environment. METHODS: Twenty-three pigs underwent transabdominal patch arteriotomy of the infrarenal aorta with either Dacron or GBP. The patches were inoculated with sterile saline (1 per group), Staphylococcus aureus 10(4) colony-forming units (CFUs) (4 per group), or S. aureus 10(5) CFUs (6 per group). At 3 wk, the animals were euthanized, and the patches were removed via a left retroperitoneal approach. Specimens were collected for microbiologic and histologic analysis. RESULTS: One animal from each group inoculated with 10(5) CFUs died during the study period, and another died immediately postoperatively of an airway complication. All aortas were patent and without evidence of pseudoaneurysm formation. Gross abscesses were found in 4/6 Dacron and 5/6 GBP animals receiving 10(5) CFUs. Similarly, 4/6 animals implanted with Dacron and 5/6 animals implanted with GBP had positive tissue cultures. A histologic grading system of inflammation substantiated the culture results. CONCLUSIONS: No significant difference exists between Dacron and GBP to resist bacterial infection at 3 wk. We have established a reproducible in vivo model to study arterial patch materials in a topically infected environment.

Evaluation of reproduction and raising offspring in a nursery-reared SPF baboon (Papio hamadryas anubis) colony.

Baboons (Papio hamadryas anubis) of a conventional breeding colony were nursery-reared to create a specific pathogen-free (SPF) baboon-breeding program. Because the founding generations were nursery-reared until 2 years of age, it was suspected that the SPF baboons would exhibit increased reproductive challenges as adults. Mothering behavior was of interest, because SPF females were not exposed to parental role models during the nursery-rearing process. We compared reproductive data from the SPF baboon breeding program during its first 10 years with data from age-matched baboons during the same period from an established, genetically-similar conventional breeding colony. We also evaluated records documenting mother-infant behaviors within the SPF colony. The average age of menarche in SPF females was 3.3 years. The overall live birth rate of both SPF and conventional females was approximately 90%, with no difference in pregnancy outcome between the two colonies. The average age at first conception for SPF females was earlier (4.2 years) than that of the conventional females (4.7 years). In both colonies, primiparous females were more likely to abort than multiparous females. Similarly, primiparous females were more likely to lose their infants to death or human intervention. A mothering score system was developed in the SPF colony to facilitate intervention of poor mother-infant relationships. Records revealed 70% of SPF mothers were able to raise one or more of their infants successfully to at least 180 days of age, which did not differ from conventional mothers. SPF females returned to post-partum amenorrhea 27 days sooner on average than the conventional females, independent of dam age. The nursery-rearing process used for recruitment into the SPF colony therefore did not have an adverse effect on reproduction or rearing offspring.

Characterization of novel mouse models to study the role of necroptosis in aging and age-related diseases.

To study the impact of necroptosis-induced chronic inflammation on age-related diseases and aging, two knockin mouse models (Ripk3-KI and Mlkl-KI) were generated that overexpress two genes involved in necroptosis (Ripk3 or Mlkl) when crossed to Cre transgenic mice. Crossing Ripk3-KI or Mlkl-KI mice to albumin-Cre transgenic mice produced hepatocyte specific hRipk3-KI or hMlkl-KI mice, which express the two transgenes only in the liver. Ripk3 and Mlkl proteins were overexpressed 10- and fourfold, respectively, in the livers of the hRipk3-KI or hMlkl-KI mice. Treating young (2-month) hRipk3-KI or hMlkl-KI mice with carbon tetrachloride (CCl4), a chemical inducer of oxidative stress, resulted in increased necroptosis (Mlkl-oligomers) and inflammation in the liver compared to control mice receiving CCl4. Mlkl-oligomerization also was significantly increased in old (18-month) hRipk3-KI and hMlkl-KI mice compared to old control (Cre negative, Ripk3-KI and Mlkl-KI) mice. The increase in necroptosis was associated with an increase in inflammation, e.g., inflammatory cytokines (TNFα, IL-6) and macrophage markers (F4/80, CD68). Importantly, steatosis (triglycerides) and fibrosis (e.g., picrosirius red staining, hydroxyproline levels, and transcripts for TGFß, Col1α1, and Col3α1) that increase with age were significantly higher in the livers of the old hRipk3-KI or hMlkl-KI mice compared to old control mice. In addition, markers of cellular senescence were significantly increased in the livers of the old hRipk3-KI and hMlkl-KI mice. Thus, the first mouse models have been developed that allow researchers to study the impact of inducing necroptosis in specific cells/tissues on chronic inflammation in aging and age-related diseases.

Polycaprolactone Electrospun Nanofiber Membrane with Skin Graft Containing Collagen and Bandage Containing MgO Nanoparticles for Wound Healing Applications.

The objective of this study was to create a nanofiber-based skin graft with an antimicrobial bandage that could accelerate the healing of an open wound while minimizing infection. To this end, we prepared a bi-layer construct where the top layer acts as bandage, and the bottom layer acts as a dermal equivalent graft. A collagen (CG) gel was combined without and with an electrospun polycaprolactone (PCL) membrane to prepare CG and CG-PCL dermal equivalent constructs. The antibacterial properties of PCL with and without an antibacterial agent (MgO nanoparticles) against Staphylococcus aureus (ATCC 6538) was also examined. Human dermal fibroblasts were cultured in each construct to make the dermal equivalent grafts. After culturing, keratinocytes were plated on top of the tissues to allow growth of an epidermis. Rheological and durability tests were conducted on in vitro dermal and skin equivalent cultures, and we found that PCL significantly affects CG-PCL graft biological and mechanical strength (rheology and durability). PCL presence in the dermal equivalent allowed sufficient tension generation to activate fibroblasts and myofibroblasts in the presence of transforming growth factor-beta. During culture of the skin equivalents, optical coherence tomography (OCT) showed layers corresponding to dermal and epidermal compartments in the presence or absence of PCL; this was confirmed after fixed specimens were histologically sectioned and stained. MgO added to PCL showed antibacterial activity against S. aureus. In vivo animal studies using a rat skin model showed that a polycaprolactone nanofiber bandage containing a type I collagen skin graft has potential for wound healing applications.

A Genetically Heterogeneous Rat Model with Divergent Mitochondrial Genomes.

We generated a genetically heterogenous rat model by a 4-way cross strategy using 4 inbred strains (Brown Norway [BN], Fischer 344 [F344], Lewis [LEW], and Wistar Kyoto [KY]) to provide investigators with a highly genetically diverse rat model from commercially available inbred rats. We made reciprocal crosses between males and females from the 2 F1 hybrids to generate genetically heterogeneous rats with mitochondrial genomes from either the BN (OKC-HETB, a.k.a "B" genotype) or WKY (OKC-HETW a.k.a "W" genotype) parental strains. These two mitochondrial genomes differ at 94 nucleotides, more akin to human mitochondrial genome diversity than that available in classical laboratory mouse strains. Body weights of the B and W genotypes were similar. However, mitochondrial genotype antagonistically affected grip strength and treadmill endurance in females only. In addition, mitochondrial genotype significantly affected multiple responses to a high-fat diet (HFD) and treatment with 17α-estradiol. Contrary to findings in mice in which males only are affected by 17α-estradiol supplementation, female rats fed a HFD beneficially responded to 17α-estradiol treatment as evidenced by declines in body mass, adiposity, and liver mass. Male rats, by contrast, differed in a mitochondrial genotype-specific manner, with only B males responding to 17α-estradiol treatment. Mitochondrial genotype and sex differences were also observed in features of brain-specific antioxidant response to a HFD and 17α-estradiol as shown by hippocampal levels of Sod2 acetylation, JNK, and FoxO3a. These results emphasize the importance of mitochondrial genotype in assessing responses to putative interventions in aging processes.

The effect of season on inflammatory response in captive baboons.

INTRODUCTION: Highly seasonal animals demonstrate predictable changes in immune function that coincide with changes in photoperiod. Little is known about the effect of season on immune response in baboons. The objective of this study was to determine the effect of season on inflammatory response in baboons. MATERIALS AND METHODS: Peripheral blood mononuclear cell cytokine response following immune stimulation and serum markers of inflammation were assessed during each season in two groups of young male baboons: one housed under natural light and one in a controlled environment of 12 hours light:12 hours dark. RESULTS: A seasonal immune rhythm was evident in both groups, with a greater TNF-α and IL-6 response to stimulation and serum CRP concentration in June and September compared with December. CONCLUSIONS: Season is an important experimental confounder, and therefore, time of year should be controlled when designing studies and analyzing data from immune studies in baboons.

T-lymphocyte homeostasis and function in infant baboons: implications for transplantation.

Laboratory mice are born lymphopenic and demonstrate lymphopenia-induced proliferation that generates memory T cells, yet they are prone to immunologic tolerance. Here we tested whether these fundamental immunologic observations apply to higher animals by studying the immune system of infant baboons. Using flow cytometry of the peripheral blood cells, it was found that baboons are born relatively lymphopenic and subsequently expand their initially naïve T cell pool with increasing numbers of memory T cells. After transplantation of an artery patch allograft or xenograft, non-immunosuppressed recipients readily mounted an immune response against donor-type antigens, as evidenced by mixed lymphocyte reaction. Immunosuppression with anti-thymocyte globulin (ATG), anti-CD154 mAb, and mycophenolate mofetil prevented T cell-mediated rejection. After lymphocyte depletion with ATG, homeostatic T cell proliferation was observed. In conclusion, the baboon proved a suitable model to investigate the infant immune system. In this study, neonatal lymphopenia and expansion of the memory T cell population were observed but, unlike mice, there were no indications that infant baboons are prone to T cell tolerance. The expansion of memory T cells during the neonatal period or after induction therapy may actually form an obstacle to tapering immunosuppressive therapy, or ultimately achieving immunologic tolerance.

Preclinical prophylactic efficacy testing of Sm-p80-based vaccine in a nonhuman primate model of Schistosoma mansoni infection and immunoglobulin G and E responses to Sm-p80 in human serum samples from an area where schistosomiasis is endemic.

The prophylactic efficacy of a schistosome antigen (Sm-p80) was tested in a nonhuman primate model, the baboon. Using a total of 28 baboons, different vaccination strategies were used including recombinant Sm-p80 protein formulated in Toll-like receptor 7 and Toll-like receptor 9 agonists, and DNA priming followed by boosting with protein plus adjuvants. Recombinant protein approaches provided levels of prophylactic efficacy of 52%-58%, whereas prime-boost approaches conferred 38%-47% protection in baboons. An appropriately balanced pro-inflammatory (T-helper 17 [Th17] and Th1) and anti-inflammatory (Th2) type of response was generated; the Th1 and Th17 types of immune responses appear to be indicative of increased prophylactic efficacy. Production and expression of several cytokines (interleukin 2 [IL-2], interferon γ, IL-12α, IL-1ß, IL-6, and IL-22) were up-regulated in vaccinated animals. Human correlate studies revealed Sm-p80 reactivity with immunoglobulin G in human serum samples from schistosome-infected individuals. In addition, a complete lack of prevailing Sm-p80-specific immunoglobulin E in a high-risk or infected population was observed, thus minimizing the risk of hypersensitivity reaction following vaccination with Sm-p80 in humans. This study provided the proof of concept to move Sm-p80 forward into further preclinical development leading to human clinical trials.

Sm-p80-based DNA vaccine provides baboons with levels of protection against Schistosoma mansoni infection comparable to those achieved by the irradiated cercarial vaccine.

To date, no vaccine is available to prevent human schistosomiasis. We have targeted a protein of Schistosoma mansoni that plays an important role in the surface membrane renewal process, a mechanism widely believed to be utilized by the parasite as an immune evasion strategy. Sm-p80 antigen is a promising vaccine target because of its documented immunogenicity, protective efficacy, and antifecundity effects observed in both experimental murine and nonhuman primate models of this infectious disease. In the present study, we report that, in a vector approved for human use (VR1020), an Sm-p80-based DNA vaccine formulation confers a 46% reduction in the worm burden in a baboon (Papio anubis) model. Baboons vaccinated with Sm-p80-VR1020 had a 28% decrease in egg production after challenge with the infectious parasite. Sm-p80-VR1020 vaccine elicited robust immune responses to specific antigen Sm-p80, including immunoglobulin (Ig) G, its subtypes IgG1 and IgG2, and IgA and IgM in vaccinated animals. When stimulated in vitro with recombinant Sm-p80, peripheral blood mononuclear cells and splenocytes from baboons vaccinated with Sm-p80-VR1020 produced considerably higher levels of T helper 1 response-enhancing cytokines (interleukin [IL]-2 and interferon-gamma) than T helper 2 (Th2) response-enhancing cytokines (IL-4 and IL-10). Peripheral blood mononuclear cells produced a significantly higher number of spot-forming units for interferon-gamma than for IL-4 in enzyme-linked immunosorbent spot assays. A mixed T helper 1/T helper 2 type of humoral and T cell responses was generated after immunization with Sm-p80-VR1020. These findings again highlight the potential of Sm-p80 as a promising vaccine candidate for schistosomiasis.

Effects of Chronic Viral Infection on Lymphocyte Populations in Middle-aged Baboons (Papio anubis).

Aging of the immune system is characterized by the loss of naïve T-cells, increased inflammation, and immune function impairment. Chronic infection with cytomegalovirus is thought to play a role in age-related changes in immunity. Therefore, to assess the effect of pathogens such as cytomegalovirus on the immune system, we determined lymphocyte populations and inflammatory markers over a 3-y period in captive, middle-age baboons, with various exposure to pathogens and shedding pressure. Groups included SPF (i.e., pathogen-negative; n = 14); large-group, conventionally housed (CONV LG; pathogen- positive; n = 14), and small-group, conventionally housed (CONV SM; pathogen-positive; n = 7). All baboon groups showed a decrease in CD45RA+ CD28+ (i.e., naive) cells over time during middle age, but the rate of decline appeared faster in CONV LG baboons than in the other groups. In addition, the reduction in CD45RA+ CD28+ cells in the CONV LG baboons coincided with higher IgG levels against baboon cytomegalovirus, increased serum cortisol concentration, and a greater inflammatory phenotype. The results of this project support a role for cytomegalovirus infection in immune system alterations in middle-aged baboons.