Chesson strain Plasmodium vivax in Saimiri sciureus boliviensis monkeys

Nine Saimiri sciureus boliviensis monkeys were inoculated with sporozoites of Plasmodium vivax (Chesson strain) dissected from Anopheles stephensi mosquitoes infected by feeding on blood from infected chimpanzees. The animals were splenectomized 7 days after inoculation. Seven animals developed infections with prepatent periods ranging from 12 to 43 days (mean of 19.6 days). Parasitemias were low during the first 50 days. Maximum parasitemias in 5 animals in which the strain adapted ranged from 10,000 to 46,800 per mm3. Anopheles freeborni mosquitoes were infected by feeding on 4 of the monkeys.     

The Peruvian III strain of Plasmodium brasilianum in Saimiri sciureus boliviensis monkeys

A strain of Plasmodium brasilianum was isolated from a naturally infected Saimiri monkey from Peru and subsequently passaged to 21 splenectomized Saimiri sciureus boliviensis monkeys. Nine of 12 attempts to transmit infection by sporozoite inoculation were successful with prepatent periods ranging from 23 to 41 days. Gametocytes were infective to Anopheles freeborni, Anopheles stephensi, Anopheles dirus, Anopheles maculatus, and Anopheles gambiae mosquitoes. The strain demonstrated a high level of resistance to cure with chloroquine.     

The Uganda I/CDC strain of Plasmodium malariae in Saimiri sciureus boliviensis

The Uganda I/CDC strain of Plasmodium malariae, initially adapted to monkeys of the genus Aotus, was studied in splenectomized Saimiri sciureus boliviensis. Mean maximum parasitemia ranged from 248 to 22,134/mm3. Only 1 mosquito was infected of 2,238 examined. After the parasite was adapted to this host, infections were characterized by periods of detectable parasitemia extending up to 269 days and by sustained periods when parasite counts were greater than 1,000/mm3. After 4 linear passages, the developmental time required before the primary peak parasite count was approximately 2 mo.     

Transmission of the OS strain of Plasmodium inui to Saimiri sciureus boliviensis and Aotus azarae boliviensis monkeys by Anopheles dirus mosquitoes

Eight Saimiri and 7 Aotus monkeys were exposed to infection with the OS strain of Plasmodium inui via the bites of from 2 to 7 Anopheles dirus mosquitoes. All Saimiri monkeys developed high-level infections of from 152,000 to 500,000/mm3 after prepatent periods of from 14 to 17 days. Only 1 Aotus monkey developed a patent infection after a period of 28 days. Feeding on these animals failed to result in infection of An. dirus mosquitoes.     

Studies of the Sal I strain of Plasmodium vivax in the squirrel monkey (Saimiri sciureus)

The Sal I strain of Plasmodium vivax was successfully adapted to three phenotypes of the squirrel monkey, Saimiri sciureus. Through five linear blood passages, parasitemias in excess of 200,000/mm3 blood were attained; Bolivian phenotype Saimiri appear to develop higher peak parasitemias. Sporozoites of the Sal I strain inoculated intravenously produced patent parasitemias in all five squirrel monkeys challenged, with prepatent periods ranging from 21 to 38 days. Anopheles freeborni and An. gambiae were the most susceptible of eight anopheline species fed on infected squirrel monkeys. As a model for in vivo studies of P. vivax the Sal I strain in Saimiri has great potential.     

Infection of Saimiri boliviensis monkeys with Plasmodium coatneyi

Abundant, apparently normally developing, liver-stage parasites of Plasmodium coatneyi were demonstrated following injection of sporozoites dissected from the salivary glands of Anopheles dirus mosquitoes. Erythrocytic development was not demonstrated.     

Elevation in plasma glucagon levels in response to stress in squirrel monkeys: comparisons of two subspecies (Saimiri sciureus boliviensis and Saimiri sciureus sciureus)

Bolivian (Bo) and Brazilian (Br) squirrel monkeys (SMs) were captured and restrained to determine patterns of glucagon and glucose response. In both subspecies, plasma glucagon and glucose levels rose rapidly in response to restraint procedures; glucagon levels in BrSMs and glucose levels in both subspecies returned to basal values in 15 minutes. The magnitude of the glucagon and glucose responses differed significantly between BoSMs and BrSMs.     

Captive breeding of squirrel monkeys,Saimiri sciureus and Saimiri boliviensis: The problem of hybrid groups

The electrophoretic variability of blood proteins coding for up to 32 genetic loci was analyzed in 108 squirrel monkeys (Saimiri sciureus, Saimiri boliviensis, hybrids) from two captive colonies. Twelve polymorphic loci with 31 alleles are reported. The biallelic Ada* locus, G-statistics and Hardy-Weinberg genotype equilibria are useful for recognizing hybrids between S. sciureus and S. boliviensis. Backcrosses in hybrid stocks and gene flow in a natural hybrid belt, however, complicate the taxonomic diagnosis of captive specimens: S. sciureus phenotypes imported from Peru possessed the allele Ada*132, which generally characterizes S. boliviensis (or species hybrids). The complex taxonomy of Saimiri spp. Requires careful planning of captive breeding. We suggest a genetic analysis of the founder individuals before their inclusion in the European studbook population and to breed S. sciureus from Guyana separately from Peruvian imports, because the latter bear a greater risk of being taxonomically heterogeneous. Zoo Biol 17:95–109, 1998. © 1998 Wiley-Liss, Inc.     

Infection of Aotus azarae boliviensis monkeys with different strains of Plasmodium vivax

Sixty-seven splenectomized Aotus azarae boliviensis were infected with strains of Plasmodium vivax from Southeast Asia (2), New Guinea (2), North Korea (1), and Central America (3). Maximum parasitemias varied among the different strains, with the mean maximum parasitemia for the primary infection period being 16,200 per mm3. Animals previously infected with Plasmodium falciparum and Plasmodium malariae produced maximum parasitemias of 30,200 and 11,900 per mm3, respectively. Gametocytes infective to Anopheles freeborni mosquitoes were produced with 7 of the 8 strains examined.     

Age-related hormonal differences in cycling squirrel monkeys (Saimiri boliviensis boliviensis)

This study was planned to evaluate the poor reproductive performance of aged squirrel monkeys in a self-sustaining breeding colony. Two groups of monkeys aged 6–8 years (Group 1), and >12 years (Group 2) were evaluated. During the midbreeding season, daily blood samples were obtained for a period of 35 days from 10 animals in each group. Blood samples were assayed for serum estradiol (E), progesterone (P), and bioassayable luteinizing hormone (bio-LH) concentrations and the data were analyzed by ANOVA (analysis of variance). Bio-LH surges were less frequent in the aged breeders (Group 2). Total P output during periovulatory period (day ?;3 to day + 3) and the total P output during the luteal phases of the estrus cycles were significantly lower in aged squirrel monkeys (Group 2, P < 0.003). Although E peaks occurred less frequently in Group 2, they had higher concentrations as compared to Group 1 (P < 0.003). Cumulative periovulatory and luteal phase E levels did not differ between the two groups. The reduction in P output in aged squirrel monkeys may interfere with proper implantation, thus contributing to the lower pregnancy rate observed in this age group. The decreased frequency of bio-LH surges indicated less frequent ovulations in the aged animals which may further impair reproduction with aging. © 1994 Wiley-Liss, Inc.     

Adaptation of the Plasmodium falciparum FCB strain for in vitro and in vivo analysis in squirrel monkeys (Saimiri sciureus)

The asexual blood stages of the Plasmodium falciparum parasite are responsible for inducing the clinical symptoms and the most severe presentations of malaria infection that causes frequent mortality and morbidity in tropical and subtropical areas of the world, making the blood stages of infection a key target of new malaria treatment and prevention strategies. Progress towards the development of more effective treatment and prevention strategies has been hindered by the limited availability of infection models that permit the sequential analysis of blood stage parasites in vitro followed by in vivo analysis to confirm therapeutic benefits. To advance a model for in vitro and in vivo analysis of blood stage parasites, we examined nine laboratory strains of P. falciparum to determine which strains could adapt to growth in vivo in splenectomized squirrel monkeys (Saimiri sciureus). Only one of the nine laboratory strains tested, the FCB strain, adapted to in vivo growth. Morphological analysis show that the adapted ring-stage parasites have a different morphology from original parasites cultured in vitro, and more often they were found to localize at the edge of the infected red blood cell. No remarkable differences were observed for both trophozoites and schizonts. The adapted strain can be cultured back in vitro similar to the original parasite, indicating that the adapted parasite can develop both in vitro and in vivo. This squirrel monkey-adapted P. falciparum parasite is expected to be suitable and is advantageous for the research and development of vaccines and antimalarial drugs.     

Mycobacterium kansasii infection in squirrel monkeys (Saimiri sciureus sciureus)

Abstract: This report documents asymptomatic infections of Mycobacterium kansasii in four of five tuberculin positive squirrel monkeys (Saimiri sciureus sciureus). The mycobacterial DNA amplified by polymerase chain reaction (PCR) from a bronchial lymph node had no affinity for the species specific probes of M. tuberculosis, M. avium, and M. intracellular, thus allowing the presumptive diagnosis of an atypical mycobacterial infection. Infection by Mycobacterium kansasii was confirmed by culture of bronchial lymph nodes from three monkeys. The source of the infection was never identified.     

Anatomical distribution of developing trophozoites and schizonts of Plasmodium vivax in Aotus lemurinus lemurinus and Saimiri sciureus

Organ distribution of developing trophozoite- and schizont-infected erythrocytes of Plasmodium vivax and night monkeys, Aotus lemurinus lemurinus, and squirrel monkeys, Saimiri sciureus, was determined. The primary site for the infection in both species was the splenic vasculature. Secondary organ involvement differed between hosts although some overlapping did occur.     

Microsatellite polymorphisms in Bolivian squirrel monkeys (Saimiri boliviensis)

Two different approaches were used to identify new microsatellite polymorphisms among captive Bolivian squirrel monkeys (Saimiri boliviensis). In the first case, PCR primers for published human microsatellite loci were screened using genomic DNA from squirrel monkeys. Six polymorphic loci were identified using DNA samples from 19 unrelated individuals. The average heterozygosity among these six loci is 0.73. In the second set of experiments, a DNA library was created from Saimiri genomic DNA, and clones were selected from that library by screening with probes containing di-, tri-, and tetranucleotide repeats. Six novel microsatellites were identified this way, with an average heterozygosity of 0.59. Primer pairs for these six cloned microsatellites were also screened using a series of DNA samples from ten other platyrrhine species to assess the potential utility of these loci in other taxa. This study provides 12 new DNA polymorphisms that will be useful for various studies of this genus and demonstrates that both approaches can be used to develop new DNA polymorphisms in platyrrhine species.     

Development of a polymorphic strain of Plasmodium vivax in monkeys.

A strain of Plasmodium vivax from Thailand with a polymorphic repeat unit of the circumsporozoite protein was established in Saimiri sciureus boliviensis and 3 species of Aotus monkeys. All 11 attempts to transmit infection via sporozoite inoculation, 4 times to splenectomized S. sciureus boliviensis, 2 times to splenectomized Aotus nancymai, and 5 times to intact Saimiri monkeys, were successful. Anopheles freeborni, Anopheles stephensi, Anopheles dirus, and Anopheles gambiae mosquitoes were infected by feeding on parasitemic blood from a chimpanzee and an Aotus azarae boliviensis monkey. Our results indicate that this strain may be useful in antisporozoite vaccine trials.     

Play vocalizations of squirrel monkeys (Saimiri sciureus)

Vocalizations occurring during play bouts were studied in 2 pairs of young male squirrel monkeys. Two main call types, one having four variants, are described. Vocalization rate varied with the type of ongoing behavior and with play bout duration, an association considered to be indicative of motivation to play. Structural differences also varied with bout duration and longer bouts had longer and more complex calls. In addition to providing direct information about motivation, vocalizations may have a metacommunicative function in alerting adult group members (not play partners) to the presence of playful activity.