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PubMed1996

An immunovirological study of central nervous system involvement during HIV-1 infection of chimpanzees.

Chimpanzees infected with human immunodeficiency virus type 1 (HIV-1) are used to model acquired immunodeficiency syndrome (AIDS). Since the central nervous system (CNS) is involved in AIDS, we performed an immunovirological study in 18 chimpanzees inoculated up to 87 months prior to the study (mean, 45 months) with HIV-1 and 8 uninfected controls. Serum and cerebrospinal fluid (CSF) IgG and albumin levels of infected chimpanzees never exceeded those of controls. The CSF/serum albumin ratio was elevated in 1 of 18 infected chimpanzees compared to controls; however, all animals had an elevated ratio indicating a more open blood-brain barrier relative to humans. The intrathecal IgG production index was elevated in only 1 of 18 infected chimpanzees compared to controls. Identical serum and CSF IgG bands were found by isoelectric focusing in 2 of 8 controls and in 1 of 18 infected chimpanzees. None of these bands reacted with recombinant HIV-1 p24gag or gp 120env. HIV-1 was isolated from the peripheral blood of 4 of 18 infected chimpanzees but never from the paired CSF samples. Anti-HIV-1 antibody was detected by a enzyme-linked immunosorbent assay in 18 of 18 paired serum and CSF samples and by Western blot in 18 of 18 serum and 13 of 18 CSF samples from infected chimpanzees without a difference in pattern. Polymerase chain reaction analysis on brain tissue of one animal was negative for HIV-1 sequences. Our results demonstrate that, unlike human infection, chimpanzees inoculated with HIV-1 show no evidence of isolatable virus in the CSF and no evidence of intrathecal anti-HIV-1 antibody synthesis up to several years after experimental infection. The lack of CNS involvement may contribute to the delay or suppression of clinical disease in infected chimpanzees.

Acquired Immunodeficiency Syndrome↗
PubMed2005

A genome-wide survey of structural variation between human and chimpanzee.

Structural changes (deletions, insertions, and inversions) between human and chimpanzee genomes have likely had a significant impact on lineage-specific evolution because of their potential for dramatic and irreversible mutation. The low-quality nature of the current chimpanzee genome assembly precludes the reliable identification of many of these differences. To circumvent this, we applied a method to optimally map chimpanzee fosmid paired-end sequences against the human genome to systematically identify sites of structural variation > or = 12 kb between the two species. Our analysis yielded a total of 651 putative sites of chimpanzee deletion (n = 293), insertions (n = 184), and rearrangements consistent with local inversions between the two genomes (n = 174). We validated a subset (19/23) of insertion and deletions using PCR and Southern blot assays, confirming the accuracy of our method. The events are distributed throughout the genome on all chromosomes but are highly correlated with sites of segmental duplication in human and chimpanzee. These structural variants encompass at least 24 Mb of DNA and overlap with > 245 genes. Seventeen of these genes contain exons missing in the chimpanzee genomic sequence and also show a significant reduction in gene expression in chimpanzee. Compared with the pioneering work of Yunis, Prakash, Dutrillaux, and Lejeune, this analysis expands the number of potential rearrangements between chimpanzees and humans 50-fold. Furthermore, this work prioritizes regions for further finishing in the chimpanzee genome and provides a resource for interrogating functional differences between humans and chimpanzees.

Animals↗
PubMed2001

Comparison of chimpanzee and human leukocyte Ig-like receptor genes reveals framework and rapidly evolving genes.

The leukocyte receptor complex (LRC) on human chromosome 19 contains related Ig superfamily killer cell Ig-like receptor (KIR) and leukocyte Ig-like receptor (LIR) genes. Previously, we discovered much difference in the KIR genes between humans and chimpanzees, primate species estimated to have approximately 98.8% genomic sequence similarity. Here, the common chimpanzee LIR genes are identified, characterized, and compared with their human counterparts. From screening a chimpanzee splenocyte cDNA library, clones corresponding to nine different chimpanzee LIRs were isolated and sequenced. Analysis of genomic DNA from 48 unrelated chimpanzees showed 42 to have all nine LIR genes, and six animals to lack just one of the genes. In structural diversity and functional type, the chimpanzee LIRs cover the range of human LIRs. Although both species have the same number of inhibitory LIRs, humans have more activating receptors, a trend also seen for KIRs. Four chimpanzee LIRs are clearly orthologs of human LIRs. Five other chimpanzee LIRs have paralogous relationships with clusters of human LIRs and have undergone much recombination. Like the human genes, chimpanzee LIR genes appear to be organized into two duplicated blocks, each block containing two orthologous genes. This organization provides a conserved framework within which there are clusters of faster evolving genes. Human and chimpanzee KIR genes have an analogous arrangement. Whereas both KIR and LIR genes can exhibit greater interspecies differences than the genome average, within each species the LIR gene family is more conserved than the KIR gene family.

Animals↗
PubMed2002

Conservation and variation in human and common chimpanzee CD94 and NKG2 genes.

To assess polymorphism and variation in human and chimpanzee NK complex genes, we determined the coding-region sequences for CD94 and NKG2A, C, D, E, and F from several human (Homo sapiens) donors and common chimpanzees (Pan troglodytes). CD94 is highly conserved, while the NKG2 genes exhibit some polymorphism. For all the genes, alternative mRNA splicing variants were frequent among the clones obtained by RT-PCR. Alternative splicing acts similarly in human and chimpanzee to produce the CD94B variant from the CD94 gene and the NKG2B variant from the NKG2A gene. Whereas single chimpanzee orthologs for CD94, NKG2A, NKG2E, and NKG2F were identified, two chimpanzee paralogs of the human NKG2C gene were defined. The chimpanzee Pt-NKG2CI gene encodes a protein similar to human NKG2C, whereas in the chimpanzee Pt-NKG2CII gene the translation frame changes near the beginning of the carbohydrate recognition domain, causing premature termination. Analysis of a panel of chimpanzee NK cell clones showed that Pt-NKG2CI and Pt-NKG2CII are independently and clonally expressed. Pt-NKG2CI and Pt-NKG2CII are equally diverged from human NKG2C, indicating that they arose by gene duplication subsequent to the divergence of chimpanzee and human ancestors. Genomic DNA from 80 individuals representing six primate species were typed for the presence of CD94 and NKG2. Each species gave distinctive typing patterns, with NKG2A and CD94 being most conserved. Seven different NK complex genotypes within the panel of 48 common chimpanzees were due to differences in Pt-NKG2C and Pt-NKG2D genes.

Alleles↗
PubMed2004

Normal vaginal flora in chimpanzees (Pan troglodytes): qualitative and quantitative study.

Lactobacilli are the predominant microorganisms in the vaginal flora of human beings, and are known to play an important role in protecting them from genital infections. On the other hand, the composition of the vaginal flora differs among laboratory animal species, and lactobacilli are not the predominant vaginal microorganism in many laboratory animals. We speculated that the vaginal flora of chimpanzees would be more similar to those of human beings than to those of other animal species, because chimpanzees are phylogenetically close to human beings, and their reproductive physiology is similar to that of human beings. To clarify our speculation, we examined the development of the vaginal flora in chimpanzees (Pan troglodytes). Streptococci, lactobacilli, and members of the family Bacteroidaceae were the most predominant bacteria in the vagina of mature chimpanzees (9 to 22 years old). During development of the vaginal flora of chimpanzees, the total number of bacteria increased with age and reached a plateau just before sexual maturity (5 to 7 years of age; juvenile period). Lactobacilli were already one of the predominant bacteria before sexual maturity. In mature chimpanzees, the total number of bacteria (aerobes and anaerobes) in the vagina was highest during the swelling phase of the menstrual cycle. During the swelling phase in mature chimpanzees, streptococci, lactobacilli, and Bacteroidaceae were the most frequently isolated (100%) organisms, and the total number of organisms recovered from vaginal specimens from these three groups was the highest. In mature chimpanzees in which the number of bacteria was the highest, lactobacilli were the predominant bacteria. Taken together, these results suggest that these three bacterial groups (streptococci, lactobacilli, and Bacteroidaceae) are indigenous to the vagina of chimpanzees, and chimpanzees would be the most suitable laboratory animals for studying the role of lactobacilli in the vagina of human beings.

Age Factors↗
PubMed1994

Primary sequence of an alternatively spliced form of CR1. Candidate for the 75,000 M(r) complement receptor expressed on chimpanzee erythrocytes.

Chimpanzee erythrocytes express a 75,000 M(r) complement receptor (E-CR) that binds C3b bearing immune complexes and is recognized by an anti-CR1 mAb (E11). Human erythrocytes express the type 1 CR (CR1), the most common form being 220,000 M(r) and consisting of 30 short consensus repeats (SCRs) for its entire extracellular region. The purpose of this investigation was to determine the structure of the 75,000 M(r) chimpanzee E-CR. A chimpanzee cell line was identified that expressed a 220,000 M(r) CR1, and a 75,000 M(r) molecule that was recognized by E11 and could bind human C3i. Utilizing this cell line, chimpanzee CR1 cDNA was amplified in overlapping segments by the PCR, using primer pairs specific for various regions of human CR1 cDNA. Direct sequencing of the PCR-amplified products revealed 6044 nucleotides encoding the entire 220,000 M(r) chimpanzee CR1. This nucleotide sequence was 98.8% homologous to that of the human 220,000 M(r) CR1. Amplification using a CR1 primer from the signal peptide and from the cytoplasmic region yielded a 1985-bp PCR product, termed CR1a. The CR1a sequence was identical with the sequence encoding SCRs 1 to 6, SCRs 28 to 30, and the transmembrane and cytoplasmic regions of chimpanzee CR1. This alternatively spliced product of chimpanzee CR1 would encode a protein of 71,000 peptide m.w. with six potential N-glycosylation sites. Amplification employing a CR1 primer from SCR 1 and from the 3' untranslated region yielded a second PCR product of 1731 bp. This sequence, termed CR1b, encoded eight SCRs, followed by a hydrophobic region that ended in a stop codon. The first six SCRs of CR1b were closer in homology to the first six SCRs of a human CR1-like genomic sequence (97.4%) than to those of the chimpanzee CR1 (94.8%). Taken together, these sequence data suggest that the 75,000 M(r) chimpanzee E-CR is encoded by CR1a, an alternative splice variant of chimpanzee CR1. The CR1b is presumably derived from an RNA species related to the CR1-like genomic sequence previously described only in humans.

Alternative Splicing↗
PubMed1998

Chimpanzee variation facilitates the interpretation of the incisive suture closure in South African Plio-Pleistocene hominids.

For a better understanding of early hominid growth patterns, we need to compare skeletal maturation among humans and chimpanzees. This study provides new data on variation of the incisive suture closure in extant species to facilitate the understanding of growth patterns among South African Plio-Pleistocene hominids. The complete anterior closure of the incisive suture occurs early during human life, mostly before birth. In contrast, in chimpanzees a complete anterior closure occurs mostly after the eruption of either the first permanent molars (pygmy chimpanzees) or the third molars (common chimpanzees). The first aim of this study is to test whether the patterns of closure of both the anterior and palatal components of the incisive suture in chimpanzees accurately mirror their polytypism by investigating 720 museum specimens of known geographical origin. Then we use the data gleaned from the incisive suture closure in chimpanzees to determine whether there are different growth patterns among South African Plio-Pleistocene hominids and to interpret them. Results about the pattern of incisive suture closure are consistent with the differences among chimpanzees as revealed by molecular data. Thus, the variation in chimpanzee patterns of incisive suture closure facilitates the interpretation of morphology in South African fossil hominids. In Australopithecus (Paranthropus) robustus as compared to Australopithecus africanus, the complete anterior closure and, probably, the complete palatal closure of the incisive suture occurs during early life in the same way as they occur in humans. Moreover, the closure pattern observed on Stw 53, a supposed early Homo from Sterkfontein Member 5, is similar to that seen in A. africanus and in chimpanzees. Thus, with respect to the anterior component of the incisive suture, A. africanus and Stw 53 retain the primitive feature for which A. (P.) robustus and Homo share the derived character state. Finally, it is worth noting that the Taung child does not show the robust condition.

Animals↗
PubMed1999

Demographic influences on the hunting behavior of chimpanzees.

We investigated hunting in an unusually large community of wild chimpanzees at Ngogo in the Kibale National Park, Uganda. Aspects of predation were recorded with respect to the prey, the predators, and hunting episodes. During 23 months of observation, the Ngogo chimpanzees caught 128 prey items from four primate and three ungulate species. Chimpanzees preyed selectively on immature red colobus primarily during group hunts, with adult males making the majority of kills. Party size and composition were significant predictors of the probability that chimpanzees would hunt and of their success during attempts. Chimpanzees were more likely to hunt red colobus if party size and the number of male hunters were large; party size and the number of male hunters were also significantly larger in successful compared with unsuccessful hunts. The Ngogo chimpanzees did not appear to hunt cooperatively, but reciprocal meat-sharing typically took place after kills. Hunts occurred throughout the year, though there was some seasonality as displayed by periodic hunting binges. The extremely high success rate and large number of kills made per successful hunt are the two most striking aspects of predation by the Ngogo chimpanzees. We compare currently available observations of chimpanzee hunting behavior across study sites and conclude that the large size of the Ngogo community contributes to their extraordinary hunting success. Demographic differences between groups are likely to contribute to other patterns of interpopulation variation in chimpanzee predation.

Animals↗
PubMed2000

Injury risks among chimpanzees in three housing conditions.

Meeting the psychological needs of chimpanzees (Pan troglodytes) can be a challenge given their aggressiveness on the one hand and the complexity of their social lives on the other. It is unclear how to balance the need to provide opportunities for species-appropriate behavior against potential risks of injury chimpanzees may inflict on each other. This study evaluates the suggestion that simpler social environments protect chimpanzees from wounding. Over a two-year period all visible injuries to 46 adult males, 64 adult females, and 25 immature chimpanzees were recorded at the Yerkes Regional Primate Research Center. Approximately half of the subjects were mother-reared, and the rest were nursery-reared. Housing included compounds containing about 20 chimpanzees, interconnected indoor-outdoor runs for groups of up to 12 individuals, and smaller indoor-outdoor runs for pairs and trios. Annual wounding rates were calculated for serious wounds (extensive injuries and all those requiring veterinary intervention) as well as for minor wounds. Compound-housed chimpanzees incurred the highest level of minor wounding, but serious wounding levels were not affected by housing condition. Even with a period of dominance instability and elevated levels of wounding in one compound, compound chimpanzees were not injured more than those in smaller social groups over the long term. Nursery-reared females in moderate-sized groups were wounded more than mother-reared females. Also, nursery-reared males and females were wounded less often when paired with mother-reared companions. Overall, this study indicates that maintaining chimpanzees in pairs and trios would not be an effective means for reducing injuries. The management of wounding in chimpanzee colonies is influenced more by the sex and rearing composition of a colony.

Aggression↗
PubMed2004

Demographic parameters and life history of chimpanzees at Bossou, Guinea.

Demographic parameters of wild chimpanzees at Bossou, Guinea, are presented and compared with those of other populations. The population size of Bossou chimpanzees has been stable over the last 26 years, except during two incidents of partial deforestation. The annual birth rate for a female (mean = 0.194, but 0.165 when the infant survived more than 4 years) and interbirth interval are not much different from those of other study sites. The primiparous age of Bossou chimpanzees, however, is far younger (mean = 10.9 years) than for all other known wild chimpanzee populations. The infant and juvenile survival rate is also the highest (female = 0.64, male = 0.52 for the first 8 years). As a result, the lifetime reproductive success of Bossou chimpanzees is estimated to be highest among long-term study sites. The rate of disappearance from Bossou dramatically increases during the adolescent stage, and most young chimpanzees disappear before or around maturation. Probably because the environmental capacity for chimpanzees at Bossou is at its limit, many young independent males, as well as females, have to disperse, though others may die. For chimpanzee alpha males of other populations, mature males may be needed as collaborators to defend resources. In the case of Bossou, however, a lack of adjacent groups, conspecific competitors, predators, and perhaps medium-sized mammals as prey for group hunting may eliminate this need of the alpha male for other males. The reasons why all males of other chimpanzee populations persist in being philopatric for life and maintain kin-related male bonds differing from most mammal species, including humans, are discussed.

Animals↗
PubMedDate not supplied

Further studies by immunofluorescence of the monoclonal antibodies associated with experimental non-A, non-B hepatitis in chimpanzees and their relation to D hepatitis.

To further investigate the specificity of the monoclonal antibodies (48-1 and S-1) associated with non-A, non-B hepatitis, extensive immunofluorescence studies were performed on liver biopsy specimens from chimpanzees with experimental hepatitis A, B, non-A, non-B or delta, or from normal chimpanzees. Both 48-1 and S-1 antibodies reacted in the same manner with liver biopsy specimens from 47 of 50 (94%) chimpanzees with acute or chronic non-A, non-B hepatitis and 15 of 18 (83%) chimpanzees with type D hepatitis. Examinations of serial liver biopsy specimens revealed that the duration of expression of the antigen reacting with the antibodies in hepatocytes of chimpanzees infected with non-A, non-B viruses appeared to be longer than that of chimpanzees infected with the hepatitis delta-virus. By thin-section electron microscopy, the presence of the microtubular aggregates, identical to those previously described for chimpanzees with non-A, non-B hepatitis and shown by immunoelectron microscopy to react with the antibodies, was noted in hepatocytes during the acute phase of hepatitis delta-virus. The antibodies did not react with liver biopsy specimens from chimpanzees acutely or chronically infected with hepatitis B virus or hepatitis A virus, or from normal chimpanzees. The present results confirm our previous observations with the 48-1 and S-1 antibodies. Furthermore, the finding that these two antibodies were also associated with hepatitis D would support the possibility that non-A, non-B agents and the hepatitis delta-virus may have a similar nature or may elicit a similar host response.

Animals↗
PubMed1994

Influence of antibodies to the hypervariable region of E2/NS1 glycoprotein on the selective replication of hepatitis C virus in chimpanzees.

A human plasma (inoculum one) containing hepatitis C virus (HCV) was passaged through eight chimpanzees in three generations. Of 10 HCV clones propagated from it, 7 were different in respect to the hypervariable region of E2/NS1 glycoprotein and they were named clones A, B, C, etc. A chimpanzee received inoculum one, and clone A accounted for 7 of the 10 clones from his acute-phase plasma (inoculum two). Five chimpanzees received inoculum two, and clone A accounted for 5 to 9 of the 10 clones each from their preacute plasma, which were pooled to make inoculum three. Of 10 HCV clones from inoculum three, 4 were A, 5 were B/B', and the remaining 1 was C. Two chimpanzees received inoculum three or its CsCl fraction, and all 40 clones from their acute-phase plasma were A. Thus, clone A in inoculum one was selected by chimpanzees during three passages. HCV virions in the three inocula were separated into free and immunoglobulin-bound forms by sucrose density fractionation. HCV virions in inocula one and two were heterogeneous in the sequence of hypervariable region and predominantly free of immunoglobulins. By contrast, inoculum three contained both free virions of predominantly A and immunoglobulin-bound virions which were heterogeneous. Antibodies to the hypervariable region were determined by enzyme immunoassays with overlapping synthetic decapeptides. Antibodies to clone A were detected in one chimpanzee who received inoculum two, and those to clones B and C in two chimpanzees including him and in inoculum three. Antibodies were not detectable in inoculum one or two or in the other chimpanzees. These results indicate that antibodies to the hypervariable region of E2/NS1 glycoprotein would be protective and contribute toward the selective replication of HCV in chimpanzees.

Adult↗
PubMed2000

The chimpanzee and cynomolgus monkey erythrocyte immune adherence receptors are encoded by CR1-like genes.

The human erythrocyte immune adherence (IA) receptor is the Mr 220,000 type one complement receptor, or CR1. Nonhuman primate IA receptors are comprised of a family of smaller erythrocyte complement receptors (E-CRs) of unknown origin. Recently, the Mr 65,000 baboon E-CR was identified as a glycophosphatidylinositol (GPI)-linked protein encoded by a partially duplicated CR1 gene termed CR1-like. The purpose of this study was to determine the genetic origin of the Mr 75,000 chimpanzee E-CR. Two previously identified cDNAs, an alternative splice product of CR1 termed CR1a and a chimpanzee form of CR1-like, were synthesized and amplified from chimpanzee bone marrow RNA, and transiently expressed in COS-7 cells. By SDS-PAGE, the CR1a protein had a relative mobility slightly greater than chimpanzee E-CR, whereas that of the CR1-like protein was slightly less. Affinity chromatography demonstrated that little chimpanzee CR1a bound to human C3i linked to activated thiol-Sepharose (C3i-ATS), while over 50% of both chimpanzee CR1-like and chimpanzee E-CR bound to C3i-ATS. Treatment with phosphatidylinositol-specific phospholipase C (PIPLC) to assess GPI linkage released E-CR from chimpanzee erythrocytes, and E-CR from cynomolgus monkey erythrocytes. Based on size, ligand-binding specificity, and PIPLC sensitivity, we conclude that the chimpanzee E-CR is encoded by the CR1-like gene. Furthermore, based on PIPLC sensitivity, the cynomolgus monkey E-CR is also likely encoded by a CR1-like sequence. Thus, CR1-like, which is a genetic element of unknown significance in humans, is the gene that encodes the erythrocyte IA receptor of many nonhuman primates.

Amino Acid Sequence↗
PubMed2000

Major histocompatibility complex class I diversity in a West African chimpanzee population: implications for HIV research.

Human immunodeficiency virus (HIV) poses a major threat to humankind. And though, like humans, chimpanzees are susceptible to HIV infection, they are considered to be resistant to the development of the acquired immune deficiency syndrome (AIDS). Little is known about major histocompatibility complex (MHC) class I diversity in chimpanzee populations and, moreover, whether qualitative aspects of Patr class I molecules may control resistance to AIDS. To address these questions, we assayed MHC class I diversity in a West African chimpanzee population and in some animals from other subspecies of chimpanzee. Application of different techniques allowed the detection of 17 full-length Patr-A, 19 Patr-B, and 10 Patr-C alleles. All Patr-A alleles cluster only into the HLA-A1/A3/A11 family, which supports the idea that chimpanzees have experienced a reduction in their repertoire of A locus alleles. The Patr-B alleles do not cluster in the same lineages as their human equivalents, due to frequent exchange of polymorphic sequence motifs. Furthermore, polymorphic motifs may have been exchanged between Patr-A and Patr-B loci, resulting in convergence. With regard to evolutionary stability, the Patr-C locus is more similar to the Patr-A locus than it is to the Patr-B locus. Despite the relatively low number of animals analyzed, humans and chimpanzees were ascertained as sharing similar degrees of diversity at the contact residues constituting the B and F pockets in the peptide-binding side of MHC class I molecules. Our results indicate that within a small sample of a West African chimpanzee population, a high degree of Patr class I diversity is encountered. This is in agreement with the fact that chimpanzees display more mitochondrial DNA variation than humans. In addition, population analyses demonstrated that particular Patr-B molecules, with the capacity to bind conserved HIV-1 epitopes, are characterized by high gene frequencies. These findings have important implications for evaluating immune responses in HIV vaccine studies and, more importantly, may help in understanding the relative resistance of chimpanzees to AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed2004

Chimpanzees' constructional praxis (Pan paniscus, P. troglodytes).

This study investigated chimpanzees' spontaneous spatial constructions with objects and especially their ability to repeat inter-object spatial relations, which is basic to understanding spatial relations at a higher level than perception or recognition. Subjects were six chimpanzees-four chimpanzees and two bonobos-aged 6-21 years, all raised in a human environment from an early age. Only minor species differences, but considerable individual differences were found. The effect of different object samples was assessed through a comparison with a previous study. A common overall chimpanzee pattern was also found. Chimpanzees repeated different types of inter-object spatial relations such as insertion (I), or vertical (V), or next-to (H) relations. However chimpanzees repeated I or V relations with more advanced procedures than when repeating H relations. Moreover, chimpanzees never repeated combined HV relations. Compared with children, chimpanzees showed a specific difficulty in repeating H relations. Repeating H relations is crucial for representing and understanding multiple reciprocal spatial relations between detached elements and for coordinating independent positions in space. Therefore, the chimpanzees' difficulty indicates a fundamental difference in constructive space in comparison to humans. The findings are discussed in relation to issues of spatial cognition and tool use.

Animals↗
PubMed2006

Comparing infant and juvenile behavior in bonobos (Pan paniscus) and chimpanzees (Pan troglodytes): a preliminary study.

The dichotomy between the two Pan species, the bonobo (Pan paniscus) and chimpanzee (Pan troglodytes) has been strongly emphasized until very recently. Given that most studies were primarily based on adult individuals, we shifted the "continuity versus discontinuity" discussion to the infant and juvenile stage. Our aim was to test quantitatively, some conflicting statements made in literature considering species differences between immature bonobos and chimpanzees. On one hand it is suggested that infant bonobos show retardation in motor and social development when compared with chimpanzees. Additionally it is expected that the weaning process is more traumatic to chimpanzee than bonobo infants. But on the other hand the development of behaviors is expected to be very similar in both species. We observed eight mother-infant pairs of each species in several European zoos. Our preliminary research partially confirms that immature chimpanzees seem spatially more independent, spending more time at a larger distance from their mother than immature bonobos. However, the other data do not seem to support the hypothesis that bonobo infants show retardation of motor or social development. The development of solitary play, environmental exploration, social play, non-copulatory mounts and aggressive interactions do not differ between the species. Bonobo infants in general even groom other group members more than chimpanzee infants. We also found that older bonobo infants have more nipple contact than same aged chimpanzees and that the weaning process seems to end later for bonobos than for immature chimpanzee. Additionally, although immature bonobos show in general more signs of distress, our data suggest that the weaning period itself is more traumatic for chimpanzees.

Age Factors↗
PubMed1992

Inactivated hepatitis A vaccine: active and passive immunoprophylaxis in chimpanzees.

Studies of active and passive immunoprophylaxis were carried out in chimpanzees to determine whether a candidate hepatitis A virus (HAV) vaccine could stimulate antibody to HAV (anti-HAV) that was qualitatively similar to anti-HAV stimulated by natural infection. Normal immune globulin (Ig) was prepared from plasma obtained from human volunteers before and after vaccination with the HAV vaccine, and these preparations or commercially prepared Ig were administered to chimpanzees. Protective efficacy was compared to that obtained after vaccination of chimpanzees. As expected, pre-vaccination Ig did not protect chimpanzees against challenge with virulent hepatitis A. In contrast, chimpanzees were protected against hepatitis A by Ig prepared from volunteers who had received hepatitis A vaccine. The protection was qualitatively similar to that afforded by commercial normal Ig containing convalescent anti-HAV. The minimum protective dose of passively acquired anti-HAV was approximately the minimum dose detectable by serological means. This information will be useful in calculating minimum acceptable titres of anti-HAV in normal Ig. Whereas administration of Ig protected chimpanzees against hepatitis A pathology, it did not protect them from infection with HAV. Thus, these chimpanzees were protected by classical passive-active immunoprophylaxis. In contrast, chimpanzees actively immunized with HAV vaccine were apparently protected against both hepatitis A pathology and HAV infection. The mechanism of this complete protection is unknown but may simply represent the higher titre of anti-HAV in the vaccinated chimpanzees, compared to the passively protected animals.

Animals↗
PubMed2005

gC1qR expression in chimpanzees with resolved and chronic infection: potential role of HCV core/gC1qR-mediated T cell suppression in the outcome of HCV infection.

Chimpanzee is a unique animal model for HCV infection, in which about 50% of infections resolve spontaneously. It has been reported that the magnitude of T cell responses to HCV core in recovered chimpanzees is greater than that in chronically infected ones. However, the mechanism(s) by which the chimpanzees with resolved infection overcome core-mediated immunosuppression remains unknown. In this study, we examined the effect of HCV core on T cell responsiveness in chimpanzees with resolved and chronic HCV infection. We found that core protein strongly inhibited T cell activation and proliferation in chimpanzees with chronic infection, while this inhibition was limited in chimpanzees with resolved infection. Notably, the level of gC1qR, as well as the binding of core protein, on the surface of T cells was lower in recovered chimpanzees when compared to chimpanzees with chronic HCV infection. Intriguingly, the observed differences in gC1qR expression levels and susceptibility to core-induced suppression amongst HCV-chronically infected and recovered chimpanzees were observed prior to HCV challenge, suggesting a possible genetic determination of the outcome of infection. These findings suggest that gC1qR expression on the surface of T cells is crucial for HCV core-mediated T cell suppression and viral clearance, and that represents a novel mechanism by which a virus usurps host machinery for persistence.

Animals↗