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Physiology of host parasite relationship: effects on serum alkaline phosphatase levels of fish hosts parasitized by trypanosomes.

Serum alkaline phosphatase levels of five species of fresh water fish hosts were altered by trypanosome parasites. The loss in enzymatic activity ranged from 3.91% to 69.91% in the five species of infected fishes as compared to normal level in the healthy hosts. The maximal reduction in the enzymatic activity caused by trypanosomes was observed in the herbivore carp fish Cirrhina mrigala and the minimal loss in the fresh water shark Wallago attu.

Alkaline Phosphatase

Bacteriophage introns: parasites within parasites?

Several bacteriophage introns carry the information necessary to perform a complex series of RNA as well as DNA rearrangements. The RNA splicing reactions allow expression of the intron-containing genes, whereas recombination at the DNA level results in the mobility and invasive potential of the introns. The RNA and DNA transactions are temporally regulated to permit timely splicing early in infection, and expression of intron-encoded DNA endonucleases involved in mobility at late times. This is achieved through efficient use of the viral regulatory machinery, ensuring the perpetuation of the 'parasitic' introns.

Animals

Epitopes of the human malaria parasite P. falciparum carried on the surface of HBsAg particles elicit an immune response against the parasite.

The development of recombinant subunit vaccines against pathogenic organisms requires not only the identification of epitopes eliciting a protective immune response but also suitable carriers with adjuvant function. B- and T-cell epitopes of the malaria vaccine candidate gp190 were selected on the basis of a systematic search along the gp190 molecule and by computer prediction based on the amino acid sequence. Using some of the epitopes identified, we have redesigned the surface of the hepatitis B surface antigen lipoprotein particles by replacing the major antigenic determinants with malaria-specific sequences of up to 61 amino acids in length. Upon expression via vaccinia virus the hybrid particles elicit an anti-gp190 immune response in animals. Monoclonal antibodies derived from such infections recognize the native parasite.

Amino Acid Sequence

[A new onchocercal parasite, Onchocerca alcis n. sp., parasite of the moose Alces alces in Sweden].

Among the onchocercids of cervids, Onchocerca alcis n. sp., a parasite of the moose, Alces alces, belongs to that small palearctic group of evolved onchocercids consisting of O. jakutensis, O. garmsi and O. tarsicola. It is distinguished from its most closely related species, O. jakutensis, primarily on the characters of the lateral chord and cuticle, its greater spicule ratio, and the characteristic shapes of the anterior and posterior extremities of female worms.

Animals

Genetic aspects of malaria parasite infection and the host immune response in relation to parasite evasion.

In relation to problems found up to now for the development of vaccines against malaria, recent studies have pointed out the different strategies evolved by the parasites to evade the host immune response. They include antigenic variation, antigenic polymorphism, antigenic mimicry and direct interference with the generation of the host immune response. These different mechanisms are rapidly reviewed and discussed with the aim of focusing the actual orientation of basic and applied research which has been developed to overcome these difficulties.

Animals

Erythrocyte entry by malarial parasites. A moving junction between erythrocyte and parasite.

Invasion of erythrocytes by merozoites of the monkey malaria, Plasmodium knowlesi, was investigated by electron microscopy. The apical end of the merozoite makes initial contact with the erythrocyte, creating a small depression in the erythrocyte membrane. The area of the erythrocyte membrane to which the merozoite is attached becomes thickened and forms a junction with the plasma membrane of the merozoite. As the merozoite enters the invagination in the erythrocyte surface, the junction, which is in the form of a circumferential zone of attachment between the erythrocyte and merozoite, moves along the confronted membranes to maintain its position at the orifice of the invagination. When entry is completed, the orifice closes behind the parasite in the fashion of an iris diaphragm, and the junction becomes a part of the parasitophorous vacuole. The movement of the junction during invasion is an important component of the mechanism by which the merozoite enters the erythrocyte. The extracellular merozoite is covered with a prominent surface coat. During invasion, this coat appears to be absent from the portion of the merozoite within the erythrocyte invagination, but the density of the surface coat outside the invagination (beyond the junction) is unaltered.

Animals

Parasites of domestic and wild animals in South Africa. XXVIII. Helminth and arthropod parasites of Angora goats and kids in Valley Bushveld.

Two adult Angora goats were slaughtered each month for 24 consecutive months on a farm in Valley Bushveld in the eastern Cape Province. On the same farm 2 Angora goat kids were slaughtered each month for 2 consecutive years from the time they were 1 week old until they reached 12 months of age. All these goats were processed for the recovery of helminth and arthropod parasites. Fourteen nematode species, 2 nematode genera and 1 cestode species were recovered. Worm burdens were generally low in the adult goats. Nematode burdens increased erratically in the kids reaching the greatest numbers when they were 1 year old. The tapeworm, Moniezia expansa, was present in kids at 3 or 4 months of age and had usually disappeared by the time they reached 7 months of age.

Animals

Repeat regions of malaria parasite proteins: a review of structure and possible role in the biology of the parasite.

Tandemly repeated amino acid sequences are characteristic of many malaria parasite proteins that have been sequenced to date. Strong selective pressures must exist to maintain the repeat regions and also to diversify them in the case proteins containing strain-variant repeats. Repeats have been suggested to function in immune-evasion and in binding to host receptors. This article focuses on the structural characteristics of the repeats in relation to their postulated function.

Amino Acid Sequence

Parasites of South African wildlife. VIII. Helminth and arthropod parasites of warthogs, Phacochoerus aethiopicus, in the eastern Transvaal.

Helminth and arthropod parasites were collected from 41 warthogs, Phacochoerus aethiopicus, in the Hoedspruit Nature Reserve, eastern Transvaal. This reserve consists of a military base, which is a restricted area and is surrounded by a reserve, which is open to the public. Eleven nematode species, 1 or 2 cestode species and the larvae of 2 cestode species were recovered from the animals in the reserve, and 8 nematode species and 1 or 2 cestode species were recovered from those in the military base. Oesophagostomum spp. were generally most abundant in warthogs in the reserve during the cooler months of the year, while Probstmayria vivipara also occurred in peak numbers during the cooler months, with an additional peak in October and November 1988 in warthogs in the reserve and the base, respectively. No pattern of seasonal abundance could be determined for the other helminth species. The warthogs also harboured 8 ixodid and 1 argasid tick species, 3 flea species and 1 louse species. Adult and immature Haematopinus phacochoeri were most numerous during August and September, and the largest numbers of adult Rhipicephalus simus were present from December to April.

Animals

Parasites of domestic and wild animals in South Africa. XX. Arthropod parasites of the Cape mountain zebra (Equus zebra zebra).

The arthropod parasite burdens of 14 Cape mountain zebra (Equus zebra zebra), shot for survey purposes in the Mountain Zebra National Park in the eastern Cape Province, were determined. Three species of Gasterophilus larvae and 9 ixodid tick species were recovered. Larvae of Gasterophilus pecorum were the most numerous of the fly larvae recovered and Margaropus winthemi was the most abundant tick. Two horses examined in the park were infested with 3 species of Gasterophilus larvae and 7 species of ixodid ticks.

Animals