Single Host Cell Research Articles

Host cell- and virus strain-dependent differences in oligosaccharides of hemagglutinin glycoproteins of influenza A viruses

The effect of the host cell and virus strain on the glycosylation of influenza A virus hemagglutinin glycoproteins was investigated by analysis of Pronase-digested glycopeptides labeled with radioactive sugar precursors. When influenza A/WSN virus was grown in MDBK cells, HA 1 contained both complex galactose-containing (type I) and mannose-rich (type II) glycopeptides, but HA 2 lacked type II glycopeptides. In contrast, type I and type II glycopeptides were found in HA 1 as well as HA 2 isolated from virus grown in primary chick embryo fibroblast cells, indicating that whether type I or type II oligosaccharide chains are attached to HA polypeptides is determined in part by the host cell type. However, analyses of glycopeptides from various influenza A strains representative of all human antigenic subtypes grown in a single host cell type, MDCK cells, revealed that the oligosaccharide types associated with HA polypeptides also depend on the virus strain. Both type I and type II glycopeptides were found in all strains tested, and there was no significant difference in the sizes of these glycopeptides among the strains. However, strain-dependent differences were observed in the relative amounts of type I and type II glycopeptides in virions as well as isolated glycoproteins HA 1 or HA 2. Such differences were evident among influenza A strains of the same as well as distinct HA subtypes, which suggests that changes in primary structure of the HA polypeptides induced by either antigenic drift or major antigenic shifts have caused the variation in oligosaccharide chains associated with these polypeptides.

Studies on Glugea Infection of the Ayu, Plecoglossus altivelis—I

A new species of microsporidian parasite of the ayu, Plecoglossus altivelis T. & S., is described and the name Glugea plecoglossi n. sp. is suggested.In a heavy infection of the parasite xenomas develop in large number in various organs, viz., peritoneum, visceral cavity, ovaries, testis, fat body, pyloric caeca, spleen, muscle, liver, heart, gills, iris, etc., and cause serious damage to fish. The xenomas are variable in size, being 0.5-3 mm, rarely as large as 5 mm.Fresh spores of the parasite are elongate or ellipsoidal and are 5.1-6.2×2.0-2.5μ, the average of 200 spores being 5.8×2.1μ Spores fixed in Bouin's solution and stained with Heidenhein's iron hematoxylin are 3.8-4.8×1.5-2.0μ, the average of 50 spores being 4.0×1.8μ. Everted filaments are 180μ at maximum, being 100-150μ in the majority.The processes of schizogony and sporogony of the parasite studied with artificially infected ayu are in substance the same as those reported by WEISSENBERG (1968) on Glugea anomala and by SPRAGUE and VERNICK (1968) on G. weissenbergi. A very small xenoma of 4×8μ with a single schizont and a single host cell nucleus was found in the lamina propria of the villi of the gut of an ayu killed 5 days after infection. Sporonts in smear preparations of parasite are 3×4μ and each sporont produce two spores. Therefore the parasite is classified into the genus Glugea.Inoculation experiments have shown that Salmo gairdneri is susceptible to the parasite, but Gasterosteus acelatus microcephalus is unsusceptible.Of about 15 species of Glugea in fish, G. hertwigi has spores similar in size to those of the present Glugea. But the former differs from the latter in the following points. The hosts of G. hertwigi are Osmerus mordax and O. eperlanus and it has been reported by WEISSENBERG (1968) that Gasterosteus aceleatus is susceptible to G. hertwigi. G. anomala and G. weissenbergi are distinguishable in having smaller spores, 3-6×1.5-2μ, and larger spores, 6.0-7.0×2.5-3.6μ, respectively, and in having different hosts, the sticklebacks. G. takedai which was found in the rainbow trout in Japan is distinguishable in having smaller spores, 2.8-4.9×1.7-2.3μ, and in not causing hypertrophy of the infected host cells.

Studies on Glugea Infection of the Ayu, Plecoglossus altivelis—III

A new species of microsporidian parasite of the ayu, Plecoglossus altivelis T. & S., is described and the name Glugea plecoglossi n. sp. is suggested.In a heavy infection of the parasite xenomas develop in large number in various organs, viz., peritoneum, visceral cavity, ovaries, testis, fat body, pyloric caeca, spleen, muscle, liver, heart, gills, iris, etc., and cause serious damage to fish. The xenomas are variable in size, being 0.5-3 mm, rarely as large as 5 mm.Fresh spores of the parasite are elongate or ellipsoidal and are 5.1-6.2×2.0-2.5μ, the average of 200 spores being 5.8×2.1μ Spores fixed in Bouin's solution and stained with Heidenhein's iron hematoxylin are 3.8-4.8×1.5-2.0μ, the average of 50 spores being 4.0×1.8μ. Everted filaments are 180μ at maximum, being 100-150μ in the majority.The processes of schizogony and sporogony of the parasite studied with artificially infected ayu are in substance the same as those reported by WEISSENBERG (1968) on Glugea anomala and by SPRAGUE and VERNICK (1968) on G. weissenbergi. A very small xenoma of 4×8μ with a single schizont and a single host cell nucleus was found in the lamina propria of the villi of the gut of an ayu killed 5 days after infection. Sporonts in smear preparations of parasite are 3×4μ and each sporont produce two spores. Therefore the parasite is classified into the genus Glugea.Inoculation experiments have shown that Salmo gairdneri is susceptible to the parasite, but Gasterosteus acelatus microcephalus is unsusceptible.Of about 15 species of Glugea in fish, G. hertwigi has spores similar in size to those of the present Glugea. But the former differs from the latter in the following points. The hosts of G. hertwigi are Osmerus mordax and O. eperlanus and it has been reported by WEISSENBERG (1968) that Gasterosteus aceleatus is susceptible to G. hertwigi. G. anomala and G. weissenbergi are distinguishable in having smaller spores, 3-6×1.5-2μ, and larger spores, 6.0-7.0×2.5-3.6μ, respectively, and in having different hosts, the sticklebacks. G. takedai which was found in the rainbow trout in Japan is distinguishable in having smaller spores, 2.8-4.9×1.7-2.3μ, and in not causing hypertrophy of the infected host cells.

Haemogregarina echisi n. sp. from the Saw‐Scaled Viper Echis carinatus of the Sind Region of West Pakistan

SYNOPSIS. Haemogregarina echisi n. sp. from the saw‐scaled viper Echis carinatus of West Pakistan is described. Eleven of 40 vipers were infected. The blood forms were almost entirely intraerythrocytic and were enclosed in a capsule. There was obvious hypertrophy of the host cell, and multiple infection of a single host cell was common. Extracellular forms were also present; they were longer than intracellular forms. No sexual dimorphism was noticeable. Schizogonic stages, from early to mature, were found in abundance in the lung capillaries. The number of merozoites per schizont was normally 22–25, altho as many as 38 merozoites were present in some schizonts. The few mites that could be collected from these snakes were free from any developmental stage of the parasite. Dimorphic schizogony, described in some haemogregarines, was not found. The status of the genera Hepatozoon and Haemogregarina, and the specific differentiation is discussed.

Cephaloidophora carpilodei n. sp. and C. pinguis n. sp., Gregarines of a Xanthid Crab in Hawaii*†

SYNOPSIS. Carpilodes rugatus from Coconut Island, off the windward side of Oahu, was infected to the extent of 65% with intestinal gregarines. Infection was frequently heavy, especially with the intracellular stages. Two new species of Cephaloidophora are described. C. carpilodei n. sp. showed multiple infections in single host cells; as many as three fully developed trophozoites were found in one intestinal epithelial cell of the mid‐gut. C. pinguis n. sp. was markedly different morphologically from C. carpilodei. In both species, intracellular development was prolonged with eventual production of septate trophozoites larger than the host cell. The gregariousness of the hosts was believed to facilitate intraspecific infection.Although other species of Xanthid crabs from the immediate vicinity were examined for gregarines, the other host species either were not parasitized or they contained gregarines belonging to species different from those found in C. rugatus. This was true even of host species placed in the same genus. Failure of these parasites of C. rugatus to become established in other species of Xanthids living in such close proximity is evidently due to biochemical or physiological barriers in the latter forms.

Some Aspects of the Structure and Behavior of Tobacco Mosaic Virus

The remarkable elucidation of the structure of tobacco mosaic virus ( TMV) in recent years, together with the demonstration that its nucleic acid moiety is sufficient to initiate infection, has sharply increased the tempo of research on this virus. An indication of the rapidity with which knowledge of TMV is accumulating is found in the fact that several ' excel­ lent reviews (1 to 5) have appeared recently. In this discussion we will attempt to present an integrated view of the TMV infective process, start­ ing with an account of the current knowledge of the structure and chemical composition of the virus and following this with an exposition of recent in­ formation on strain variation and induced mutation. The ensuing discus­ sion will concern the intracellular events of TMV infection. We have started with the premise that the virus-caused disease is to be understood primarily in terms of the interactions between virus and single host cells and have, therefore, limited our coverage of the enormous TMV literature to those papers that have a direct bearing on this aspect of TMV virology.

MULTIPLE VIRUS INFECTION OF SINGLE HOST CELLS

Evidence is presented to show that two or more viruses can simultaneously manifest their characteristic activities within individual epithelial cells of the normal rabbit's cornea. This evidence, together with that previously presented (1, 5, 6), makes plain that multiple virus infection of a single host cell can take place in corneal cells, in the cells of chick embryos, and in those of rabbit tumors, both benign (Shope's papilloma) and malignant. Certain implications of the findings are discussed.

Rhizophidium Polysiphoniae in the United States

The morphology and distribution of the fungi parasitizing marine plants are still so imperfectly known that additional facts concerning any of them seem worth placing on record. Among some algal material collected by Dr. T. C. NELSON in Barnegat Bay, New Jersey, and sent by him to the writer preserved in formalin, occurred a small sterile plant of Callithamnion which was observed to bear numerous sporangia of a chytridiaceous fungus. The mature sporangia were globose or nearly so, from 22 to 39 As in diameter, averaging 33 y, and closely appressed to the attacked host cell, which could be sharply distinguished from the neighboring unattacked cells by the partial or nearly complete exhaustion and decoloration of its contents. In only one instance was more than one sporangium attached to a single host cell (fig. 8). The cell contents are destroyed first at the end at which the fungus is attached (fig. 3), and by the time the sporangium becomes mature the contents of the parasitized cell are, as a rule, almost exhausted (figs. I, 2, 6, 8). In some cases a branched, rootlike mycelium, rather coarse for this genus, could be seen within the host cell and traced to the base of the sporangium (figs. I, 2, 8, 9, io). More frequently the mycelium could not be distinguished. The zoospores are from 2 to 3 g in diameter, globose or somewhat irregular in shape, and are evidently liberated through an opening developed from a papilla, of which each sporangium bears from one to several (figs. I, 4, 5). Each zoospore contains a nucleus or oil globule, and in addition a much smaller body, observed only in the spores remaining in a nearly