Infection and transmission studies with Plasmodium simiovale in the Macaca mulatta monkey.

Six different anophelines--Anopheles freeborni, An. b. balabacensis, An. maculatus, An. stephensi, An. atroparvus, and An. quadrimaculatus--were shown to be susceptible to infection with Plasmodium simiovale when fed upon splenectomized Macaca mulatta monkeys between the 1st and 26th days of patent parasitemia. Transmission was obtained via the bites of An. b. balabacensis and An. maculatus mosquitoes. Prepatent periods in M. mulatta monkeys following sporozoite inoculation ranged from 11 to 20 days with a median of 14 days.     

Infectivity of Plasmodium simium to Aotus trivirgatus monkeys and different anophelines.

Infections of Plasmodium simium were induced in splenectomized and intact Aotus trivirgatus griseimembra monkeys by parasitized blood and by sporozoites from Anopheles freeborni mosquitoes. Eleven of 13 monkeys developed infection after sporozoite inoculation; prepatent periods ranged from 11 to 25 days (mean 15.8 days). Comparative infectivity studies indicated that An, freeborni mosquitoes were the most susceptible followed by An. stephensi, An. Balabacensis balabacensis, An. maculatus, An. quadrimaculatus, An. culicifacies, and An. albimanus. Studies with 3 pupal phenotypes of An. freeborni indicated that lines containing the green and nonstriped pupal phenotypes were more susceptible than the base colony; the striped phenotype was slightly less susceptible.     

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.     

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.     

Adaptation of the AMRU-1 strain of Plasmodium vivax to Aotus and Saimiri monkeys and to four species of anopheline mosquitoes.

A chloroquine-resistant strain of Plasmodium vivax (AMRU-1) from Papua New Guinea has been adapted to grow in 4 species of Aotus monkeys (Aotus lemurinus griseimembra, Aotus vaciferans, Aotus nancymai, and Aotus azarae boliviensis), hybrid Aotus monkeys, and Saimiri boliviensis monkeys. Whereas it was possible to infect Saimiri monkeys with this parasite by inoculation of parasitized erythrocytes, only 42% of Saimiri monkeys became infected, compared to 92% of Aotus monkeys attempted. Comparative mosquito feedings showed that only A. vociferans, A. l. griseimembra, and Saimiri boliviensis monkeys produced infections in mosquitoes. Oocysts were observed on the guts of the 4 species of mosquitoes used (Anopheles gambiae, Anopheles stephensi, Anopheles freeborni, and Anopheles dirus), but sporozoite transmission was effected only with the intravenous inoculation of sporozoites from An. dirus into an A. l. griseimembra monkey.     

Studies on the Indochina I/CDC strain of Plasmodium falciparum in Colombian and Bolivian Aotus monkeys and different anophelines

The Indochina I/CDC strain of Plasmodium falciparum was isolated from a physician returning to the United States after working in the refugee camps along the Thailand-Kampuchean border. The strain was established in splenectomized Aotus monkeys from Colombia after being grown in vitro for 50 days. During the first three passages in Colombian monkeys, the parasites were not infective to Bolivian Aotus monkeys. After six intervening passages in Saimiri sciureus monkeys, the parasites produced high parasitemias in both Colombian and Bolivian Aotus, but gametocytes were no longer produced. Mosquito infections were obtained only during the first three passages in the Colombian monkeys. The most susceptible mosquito was Anopheles freeborni, followed by An. dirus, An. stephensi, An. maculatus, An. culicifacies, and, rarely, An. gambiae. Sporozoites were found in the salivary glands of the An. freeborni, An. dirus, An. stephensi, and An. maculatus.     

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.     

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.     

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.     

Studies on the Santa Lucia (El Salvador) strain of Plasmodium falciparum in Aotus trivirgatus monkeys.

The Santa Lucia strain of Plasmodium falciparum was isolated from El Salvador, Central America, and established in Aotus trivirgatus monkeys. Transmission from monkey to monkey via the bites of infected Anopheles freeborni, A. maculatus, and A, albimanus mosquitoes was obtained in 20 of 27 attempts. Prepatent periods in the monkeys ranged from 17 to 46 days with a mean of 24.3 days. Parasitemias and mortality were higher following sporozoite inoculation into animals which had been previously infected with P. vivax than in those with no previous malaria experience. Monkeys previously infected with P. vivax and P. cynomolgi had lower maximum parasitemias than those previously infected with P. vivax only.     

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.     

Transmission of different strains of Plasmodium cynomolgi to Aotus nancymaae monkeys and relapse

Forty-four splenectomized Aotus nancymaae monkeys were infected with 6 different strains of Plasmodium cynomolgi, 11 via trophozoites and 33 via sporozoites. Sporozoites from Anopheles dirus, Anopheles freeborni, Anopheles gambiae, Anopheles maculatus, and Anopheles stephensi resulted in prepatent periods ranging from 9 to 39 days (median of 15 days). Importantly, relapse was demonstrated in 5 of 5 sporozoite-induced infections with the Rossan strain following treatment with chloroquine.     

The Uganda I/CDC strain of Plasmodium malariae in Aotus lemurinus griseimembra monkeys

Two lines of the Uganda I/CDC strain of Plasmodium malariae were studied in splenectomized Aotus lemurinus griseimembra monkeys. A line initially adapted to these monkeys from an infected chimpanzee failed to produce high-level parasite counts or mosquito infection in 13 of this type of monkey during 16 linear passages. Another line, originally adapted from the chimpanzee to Aotus azarae boliviensis, after 7 linear passages in 3 different types of Aotus was then passaged to 14 splenectomized A. lemurinus griseimembra. Geometric mean maximum parasitemia in these monkeys was 18,400/mm3. Mosquito infections were readily obtained during the period just after the parasite count rose above 1,000/mm3. Anopheles freeborni, An. stephensi, An. dirus, and 2 strains of An. gambiae supported the development of the parasite to the presence of sporozoites in the salivary glands. Two attempts to transmit the strain to other splenectomized A. lemurinus griseimembra by sporozoite inoculation were unsuccessful.     

Observations on two strains of plasmodium falciparum from Haiti in Aotus monkeys

Two strains of Plasmodium falciparum originating in Haiti were studied in the Aotus monkey. The Haitian I/CDC strain was first adapted to in vitro cultivation and subsequently inoculated into monkeys. The Haitian III/CDC strain was inoculated directly from a human patient into the Aotus monkey. The strains varied in their levels of pathogenicity to the animals. The Haitian I/CDC strain was highly virulent in six splenectomized animals; in one intact animal, the infection could be controlled but not eliminated with periodic doses of quinine and chloroquine. After subsequent splenectomy, the animal developed high parasitemias and died. No gametocytes developed in any of the Haitian I infections. The Haitian III strain was lethal to five of the 14 splenectomized monkeys inoculated, but some were able to control their infections without drug intervention. Gametocytes developed in all infections that persisted for an adequate length of time, and infections of mosquitoes were obtained both during the primary attack and the first recrudescence of the parasitemia. Of the mosquitoes tested, Anopheles freeborni was most susceptible to infection, followed by An. culicifacies, An. dirus, An. maculatus, and An. albimanus. The Haitian III strain was successfully transmitted to four other splenectomized Aotus monkeys via sporozoite inoculation using An. freeborni.     

Adaptation of a strain of Plasmodium vivax from India to New World monkeys, chimpanzees, and anopheline mosquitoes.

A strain of Plasmodium vivax from India was adapted to develop in splenectomized Saimiri boliviensis, Aotus lemurinus griseimembra, A vociferans, A. nancymai, A. azarae boliviensis, hybrid Aotus monkeys, and splenectomized chimpanzees. Infections were induced via the inoculation of sporozoites dissected from the salivary glands of Anopheles stephensi and An. dirus mosquitoes to 12 Aotus and 8 Saimiri monkeys; transmission via the bites of infected An. stephensi was made to 1 Aotus monkey and 1 chimpanzee. The intravenous passage of infected erythrocytes was made to 9 Aotus monkeys and 4 chimpanzees. Gametocytes in 13 Aotus monkeys and 4 chimpanzees were infectious to mosquitoes. Infection rates were markedly higher in mosquitoes fed on chimpanzees. PCR studies on 10 monkeys injected with sporozoites revealed the presence of parasites before their detection by microscopic examination. The India VII strain of P. vivax develops in Aotus and Saimiri monkeys and chimpanzees following the injection of parasitized erythrocytes, or sporozoites, or both. The transmission rate via sporozoites to New World monkeys of approximately 50% may be too low for the testing of sporozoite vaccines or drugs directed against the exoerythrocytic stages. However, the strain is highly infectious to commonly available laboratory-maintained anopheline mosquitoes. Mosquito infection is especially high when feedings are made with gametocytes from splenectomized chimpanzees.     

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.     

Studies on two strains of Plasmodium cynomolgi in New World and Old World monkeys and mosquitoes

Infections that cause the Gombak and Smithsonian strains of Plasmodium cynomolgi were induced in Macaca mulatta, Aotus lemurinus griseimembra, Aotus nancymai, and Saimiri boliviensis monkeys. Transmission of the Gombak strain to Aotus spp. monkeys was obtained by the injection of sporozoites dissected from the salivary glands of experimentally infected Anopheles dirus and by the bites of infected An. dirus and Anopheles farauti mosquitoes. Two S. boliviensis monkeys were infected via the injection of sporozoites dissected from An. dirus. Prepatent periods in New World monkeys ranged from 14 to 44 days, with a median of 18 days. The Smithsonian strain was transmitted via sporozoites to 1 A. lemurinus griseimembra and 9 A. nancymai monkeys. Prepatent periods ranged from 12 to 31 days.     

Infection of Aotus and Saimiri monkeys with Plasmodium gonderi

Attempts were made to infect 4 species of New World monkeys (Saimiri boliviensis, Aotus nancymai, A. vociferans, A. azarae boliviensis) with Plasmodium gonderi, a malaria parasite of African monkeys. Sporozoites were obtained from Anopheles dirus or A. stephensi mosquitoes that fed on an infected rhesus monkey (Macaca mulatta). Inoculation of sporozoites was by injection of dissected sporozoites by either the intravenous or intrahepatic routes, or by mosquito bite. Liver biopsies done 7 or 8 days after sporozoite inoculation showed that hepatocytes of all 4 species of these New World monkeys supported exoerythrocytic stages of P. gonderi, but daily blood film examination during a 60-day observation period failed to detect blood stages of the parasite.     

Rio Meta strain of Plasmodium vivax in New World monkeys and anopheline mosquitoes

An archived strain of Plasmodium vivax, isolated from Rio Meta, northern Colombia, in 1972 was adapted to grow in splenectomized Aotus lemurinus griseimembra and A. nancymai monkeys. Anopheles freeborni, An. maculatus, An. dirus, An. culicifacies, and An. albimanus were shown to be susceptible to infection by feeding on infected monkeys. Infections were more readily obtained by feeding on A. L. griseimembra than on A. nancymai. Transmission through sporozoites was obtained in an A. l. griseimembra monkey after a prepatent period of 24 days.     

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.