J. Roger Broderson

Nonhuman Primate Model for Listeria monocytogenes-Induced Stillbirths

ABSTRACT Listeria monocytogenes, isolated from outbreaks in either human or nonhuman primate populations, was administered orally at doses ranging from 106 to 1010 CFU. Four of 10 treated animals delivered stillborn infants. L. monocytogenes was isolated from fetal tissue, and the pathology was consistent with L. monocytogenes infection as the cause of pregnancy loss. For all pregnancies resulting in stillbirths, L. monocytogenes was isolated from maternal feces, indicating that L. monocytogenes had survived and had probably colonized the gastrointestinal tract. Antibodies and antigen-specific lymphocyte proliferation against Listeria increased in animals that had stillbirths.

SPOROZOITE-INDUCED INFECTIONS OF THE SALVADOR I STRAIN OF PLASMODIUM VIVAX IN SAIMIRI SCIUREUS BOLIVIENSIS MONKEYS

Twenty Saimiri sciureus boliviensis monkeys from Bolivia were inoculated intravenously with sporozoites of the Salvador I strain of Plasmodium vivax. All animals were splenectomized 7 days after inoculation. Inoculation of 100,000 sporozoites resulted in prepatent periods averaging 16.6 days; all monkeys developed high-level parasitemias with an average maximum of 103,000 per mm3. Inoculation of 10,000 sporozoites resulted in average prepatent periods of 19.4 days; one of the resulting infections produced a transient low-level parasitemia. Of 5 monkeys inoculated with 1,000 sporozoites, 4 had prepatent periods of from 24 to 35 days and 1 failed to demonstrate any parasitemia; 1 monkey supported a low-level transient parasitemia, whereas the other 3 monkeys had high-level parasitemias. It is proposed that by using a minimum inoculum of 10,000 sporozoites, the model system may be useful in the testing of anti-sporozoite vaccines directed against P. vivax.

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.

STUDIES ON THE NORTH KOREAN STRAIN OF PLASMODIUM VIVAX IN AOTUS MONKEYS AND DIFFERENT ANOPHELINES

Twenty-two Aotus monkeys of different karyotypes were infected with the North Korean strain of Plasmodium vivax. Aotus lemurinus griseimembra animals from Colombia produced higher maximum parasitemias and more readily infected mosquitoes than did Aotus monkeys from Bolivia (K-VI) or Peru (K-V and K-X). Comparative feedings indicated that the most susceptible mosquito species was Anopheles stephensi, followed by An. gambiae, An. dirus, An. freeborni, An. quadrimaculatus, An. culicifacies, and An. maculatus.

THE SPOROGONIC CYCLE OF PLASMODIUM REICHENOWI

Plasmodium reichenowi, a malarial parasite of the chimpanzee, was infective to Anopheles freeborni, Anopheles quadrimaculatus, Anopheles stephensi, Anopheles maculatus, Anopheles dirus, and Anopheles culicifacies mosquitoes. Anopheles gambiae and Anopheles albimanus were not infected. Mean oocyst diameters of P. reichenowi were smaller than those of the other chimpanzee parasite, Plasmodium schwetzi. Sporozoites were present in the salivary glands of An. freeborni at 15 days when held at 25 to 26 C.

INFECTION OF AOTUS AZARAE BOLIVIENSIS MONKEYS WITH DIFFERENT STRAINS OF PLASMODIUM FALCIPARUM

Eleven strains of Plasmodium falciparum from Asia, Africa, and Central America were inoculated into a total of 58 splenectomized Aotus azarae boliviensis monkeys. Eight of the strains produced high-level parasitemias, whereas 3 (2 from Honduras and 1 from Zaire) produced only low-level parasitemias. Mosquito infections were only obtained during the first 2 linear passages of the Santa Lucia strain from El Salvador. The results indicate that this species of Aotus monkey is highly susceptible to infection with strains of P. falciparum from different geographic areas, and therefore may be useful for a number of chemotherapeutic or immunologic studies. Its usefulness for mosquito infection studies is very limited.

SUSCEPTIBILITY OF MACACA FASCICULARIS MONKEYS FROM MAURITIUS TO DIFFERENT SPECIES OF PLASMODIUM

Macaca fascicularis monkeys from Mauritius were shown to be susceptible via sporozoite inoculation to 7 species of Plasmodium (P. fragile, P. coatneyi, P. gonderi, P. inui, P. cynomolgi, P. knowlesi, and P. fieldi), indigenous to macaques in southeastern Asia. Four monkeys were sequentially infected with different species of Plasmodium to determine maximum and course of parasitemia. In 2 nonsplenectomized monkeys, P. fragile developed maximum parasite counts of only 134 and 155/microliters. For Plasmodium knowlesi, a parasite that is life-threatening to rhesus monkeys, maximum parasite counts were 4,278 and 7,440/microliters. Plasmodium coatneyi developed to what must be considered as moderate levels. After animals underwent splenectomy, parasite counts of P. coatneyi were 58,280, 89,094, 4,464, and 43,524/microliters. The maximum parasite counts for P. gonderi (13,508 and 21,576/microliters) and P. fieldi (1,767 and 17,836/microliters) were lower than would be expected in M. mulatta. In 2 monkeys that developed patent parasitemia with P. inui, the maximum parasite counts (95,046 and 728,748/microliters) indicated that this parasite may be the best adapted species for development in these animals once infection is established. Finally, the reinfection of 2 monkeys with P. cynomolgi suggested that some animals may be basically more resistant than others, whether splenectomized or not, to the production of high-density parasitemia.

INFECTION OF AOTUS VOCIFERANS (KARYOTYPE V) MONKEYS WITH DIFFERENT STRAINS OF PLASMODIUM VIVAX

Twenty splenectomized Aotus vociferans (karyotype V) monkeys were infected with strains of Plasmodium vivax from New Guinea, North Korea, Indonesia, El Salvador, and Honduras. Peak parasite densities ranged from 4,840 to 75,500 per mm3. Gametocytes infective to different species of mosquitoes were produced with all strains of P. vivax studied. Two transmissions of the Chesson strain of P. vivax were made by the intravenous inoculation of dissected sporozoites from An. dirus mosquitoes. Prepatent periods were 16 days.

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.

Studies on a newly isolated strain of Plasmodium brasilianum in Aotus and Saimiri monkeys and different anophelines.

A strain of Plasmodium brasilianum was isolated from an Aotus vociferans monkey from Peru. The parasite readily infected Aotus monkeys from Bolivia and Columbia and Saimiri sciureus monkeys from Peru and Bolivia. Highest level mosquito infections were obtained by feeding on the Saimiri monkeys. The most susceptible mosquito was Anopheles freeborni, followed by Anopheles dirus, Anopheles stephensi, Anopheles gambiae, Anopheles culicifacies, Anopheles maculatus and Anopheles albimanus. Anopheles quadrimaculatus were also susceptible to infection. Degenerating oocysts were observed in An. dirus mosquitoes infected with this parasite. Transmission via the bites of infected An. maculatus mosquitoes was obtained to 3 Bolivian Saimiri monkeys; prepatent periods were 27, 27, and 29 days.