Primate

About: Primate is a research topic. Over the lifetime, 1250 publications have been published within this topic receiving 67388 citations. The topic is also known as: the primate order & primates.

Schistosoma mansoni infections in Cercopithecus sabaeus monkeys.

Abstract: Cercopithecus sabaeus (green) monkeys discharged eggs up to 3.5 years after initial exposure and for a comparable period after reexposure. The number and development of worms from challenge infections were similar to initial infections, but excretion of eggs was delayed after challenge. Monkeys exposed repeatedly to moderate or small numbers of cercariae tolerated a burden of worms that would have been lethal as a single initial infection. There was evidence that worms lived for 5 years, and without regression in size. Large accumulations of eggs still occurred in the liver and intestine after 5 years, and the relative numbers of immature, mature, and degenerate eggs were similar to early stages of first infections. The response of the green monkey to S. mansoni is in marked contrast to that of Macaca mulatta, which suppresses excretion of eggs after 6 to 9 months and quickly acquires strong resistance to challenge infections. The longer output of eggs by the green monkey is more like what occurs in man. A corresponding comparison of acquired resistance is not possible because too little is known about resistance imposed against schistosomes in the human host. The rhesus and the green monkeys may provide a valuable experimental model for investigating the immune mechanism against schistosomes. The green monkey may be useful in the evaluation of schistosomicidal drugs. The need for experimental hosts of human schistosomes that react to the infections more like man than the commonly used Macaca mulatta (rhesus) monkey was emphasized by Sadun et al. (1966a). Their studies and those of Sadun and Bruce (1964) on the biology and pathology of schistosomiasis in 10 species of primates showed that worm recovery rates were highest in three species of Macaca, but self-cure occurred within a few months. The baboon and chimpanzee discharged eggs for much longer periods, but worm recovery was relatively low. For other species, the infections were abortive from the beginning. Only the chimpanzee developed pipe-stem fibrosis of the liver. The need for information on other primate hosts was noted by the above authors. Information on acquired resistance among primate hosts is essentially limited to the rhesus monkey. For man, too little is known to recognize a suitable model. The current study is concerned with another primate, Cercopithecus sabaeus, the green Received for publication 22 May 1967. * Assigned to Walter Reed Army Institute of Research, Washington, D. C. (20012), with duty station at the Department of Preventive and Social Medicine, University of Ibadan, Ibadan, Nigeria. t Present address: Tropical Disease Section, Ecological Investigations Program, Communicable Disease Center, U. S. Public Health Service, San Juan, Puerto Rico. monkey, and includes observations on the length of the prepatent period, duration and pattern of egg discharge, life-span of the infection, distribution and condition of eggs in tissues, and acquired resistance. These objectives were not all completed as originally planned, due to closing of this laboratory. A number of investigators have exposed the green monkey to human schistosomes for limited objectives, and only a few animals were involved, or the infections were of short duration (Archibald, 1923; Black, 1932; Vogel and Minning, 1953; Kuntz, 1955; Vogel, 1962; Hsii and Hsii, 1962; Meisenhelder and Thompson, 1963; and Ritchie et al., 1964). The green monkey was found to discharge eggs for relatively long periods. In contrast to M. mulatta, challenge infections developed to maturity in animals that had been infected

Non-invasive Eye Tracking Methods for New World and Old World Monkeys.

Abstract: Eye-tracking methods measure what humans and other animals visually attend to in the environment. In nonhuman primates, eye tracking can be used to test hypotheses about how primates process social information. This information can further our understanding of primate behavior as well as offer unique translational potential to explore causes of or treatments for altered social processing as seen in people with neurodevelopmental disorders such as autism spectrum disorder and schizophrenia. However, previous methods for collecting eye-tracking data in nonhuman primates required some form of head restraint, which limits the opportunities for research with respect to the number of or kinds of primates that can undergo an eye-tracking study. We developed a novel, noninvasive method for collecting eye tracking data that can be used both in animals that are difficult to restrain without sedation as well as animals that are of different ages and sizes as the box size can be adjusted. Using a transport box modified with a viewing window, we collected eye-tracking data in both New (Callicebus cupreus) and Old World monkeys (Macaca mulatta) across multiple developmental time points. These monkeys had the option to move around the box and avert their eyes from the screen, yet, they demonstrated a natural interest in viewing species-specific imagery with no previous habituation to the eye-tracking paradigm. Provided with opportunistic data from voluntary viewing of stimuli, we found that juveniles viewed stimuli more than other age groups, videos were viewed more than static photo imagery, and that monkeys increased their viewing time when presented with multiple eye tracking sessions. This noninvasive approach opens new opportunities to integrate eye-tracking studies into nonhuman primate research.

Functional Imaging of Audio–Visual Selective Attention in Monkeys and Humans: How do Lapses in Monkey Performance Affect Cross-Species Correspondences?

Abstract: The cross-species correspondences and differences in how attention modulates brain responses in humans and animal models are poorly understood. We trained 2 monkeys to perform an audio-visual selective attention task during functional magnetic resonance imaging (fMRI), rewarding them to attend to stimuli in one modality while ignoring those in the other. Monkey fMRI identified regions strongly modulated by auditory or visual attention. Surprisingly, auditory attention-related modulations were much more restricted in monkeys than humans performing the same tasks during fMRI. Further analyses ruled out trivial explanations, suggesting that labile selective-attention performance was associated with inhomogeneous modulations in wide cortical regions in the monkeys. The findings provide initial insights into how audio-visual selective attention modulates the primate brain, identify sources for "lost" attention effects in monkeys, and carry implications for modeling the neurobiology of human cognition with nonhuman animals.

Identification of Owl Monkey CD4 Receptors Broadly Compatible with Early-Stage HIV-1 Isolates.

Abstract: Most HIV-1 variants isolated from early-stage human infections do not use nonhuman primate versions of the CD4 receptor for cellular entry, or they do so poorly. We and others have previously shown that CD4 has experienced strong natural selection over the course of primate speciation, but it is unclear whether this selection has influenced the functional characteristics of CD4 as an HIV-1 receptor. Surprisingly, we find that selection on CD4 has been most intense in the New World monkeys, animals that have never been found to harbor lentiviruses related to HIV-1. Based on this, we sampled CD4 genetic diversity within populations of individuals from seven different species, including five species of New World monkeys. We found that some, but not all, CD4 alleles found in Spix's owl monkeys (Aotus vociferans) encode functional receptors for early-stage human HIV-1 isolates representing all of the major group M clades (A, B, C, and D). However, only some isolates of HIV-1 subtype C can use the CD4 receptor encoded by permissive Spix's owl monkey alleles. We characterized the prevalence of functional CD4 alleles in a colony of captive Spix's owl monkeys and found that 88% of surveyed individuals are homozygous for permissive CD4 alleles, which encode an asparagine at position 39 of the receptor. We found that the CD4 receptors encoded by two other species of owl monkeys (Aotus azarae and Aotus nancymaae) also serve as functional entry receptors for early-stage isolates of HIV-1. IMPORTANCE Nonhuman primates, particularly macaques, are used for preclinical evaluation of HIV-1 vaccine candidates. However, a significant limitation of the macaque model is the fact that most circulating HIV-1 variants cannot use the macaque CD4 receptor to enter cells and have to be adapted to these species. This is particularly true for viral variants from early stages of infection, which represent the most relevant vaccine targets. In this study, we found that some individuals from captive owl monkey populations harbor CD4 alleles that are compatible with a broad collection of HIV-1 isolates, including those isolated from early in infection in highly affected populations and representing diverse subtypes.