Electron microscopy of bluetongue virus RNA

RNA fragments were released from bluetongue virus particles using the Kleinschmidt spreading technique. Electron microscopy of viruses in protein monolayers spread on urea showed that each virion liberated an average of about 6 fragments although up to 10 fragments were occasionally observed. A large variation of filament lengths was found with an average of 3,5 µm total composite length and with a maximum of 6,5 µm leading to an estimated RNA molecular mass of 13,6 X 10⁶ . In addition, a background of loose dispersed fragments was invariably found.The articles have been scanned in colour with a HP Scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Light and election microscopic observation on the development of small merozoites of Babesia bovis in Boophilus microplus larvae

The development of small pyriform merozoites of B. bovis in the granule-secreting cells of the salivary glands of B. microplus larvae, studied with a light microscope, showed a close resemblance to that of B. argentina described by Riek (1966) in the same tick vector. Development took place through a process of schizogony and resulted in the formation of many merozoites. A study of the ultrastructure of developing merozoites in the schizont revealed the following: a poorly defined outer membrane; a granular osmiophilic inner membrane; anterior and posterior polar rings; rhoptries; micronemes; microtubules; a nucleus; spherical bodies of varying size. The schizonts were membrane-bound but no parasitophorous vacuoles were seen.The articles have been scanned in colour with a HP scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to final presentyation PDF-Format

An electron microscopic study of intra-erythrocytic stages of Babesia bovis in the brain capillaries of infected splenectomized calves

Splenectomized vaccine donor calves undergoing primary reactions to Babesia bovis infections may develop cerebral babesiosis which leads to death if not treated in time. A brain biopsy was performed on an artificially-infected animal showing nervous symptoms and the tissue was immediately processed for electron microscopic examination. Virtually every erythrocyte in the brain capillaries sectioned was infected with B. bovis. Intra-erythrocytic merozoites, trophozoites and dividing trophozoites were identified. Important features of the piriform merozoites included a reduced apical complex consisting of the anterior polar ring, microtubules, rhoptries and micronemes. Unidentified membrane-bound bodies, mostly spherical in shape, were observed anterior to the nucleus. The trophozoites showed very little structural differentiation and no food vacuoles or micropores could be detected. Each trophozoite produced 2 identical merozoites and the parent cell became totally incorporated in the daughter merozoites in the multiplication process. Projections were seen radiating from the surface of infected erythrocytes which appeared to adhere to other surfaces on contact. This probably resulted in the sludging of infected erythrocytes in the capillaries. The latter observations coincide with those described for Babesia argentina.This article has been scanned in colour with a HP Scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-Format

The fine structure of intra-erythrocytic stages of Babesia bigemina

The electron microscope was used to study the structure of merozoites, merozoites in the process of transformation to trophozoites, trophozoites, and the method of multiplication of B. bigemina. The merozoites were piriform in shape and surrounded by 3 peripheral membranes of which the 2 inner ones often appeared as a single thick osmiophilic structure (inner membrane). Anterior and posterior polar rings, microtubules, micronemes, rhoptries and mitochondria with and without tubular cristae were discernible. A single large unidentified spherical body was present in most of the mature merozoites. After penetration of an erythrocyte, merozoites developed into trophozoites through a transformation process which involved the loss of the inner membrane of the pellicle, rhoptries, most of the micronemes and the spherical body. The trophozoites were surrounded by a single membrane, were pleomorphic in shape and contained large inclusions of host cell cytoplasm, but no cytostomes or food vacuoles could be identified. Reproduction took place through a process resembling schizogony resulting in the production of 2 merozoites, the cytoplasmic constituents of the original trophozoite (mother cell) being virtually entirely incorporated into the daughter cells in the process. None of the parasites were contained in parasitophorous vacuoles.The articles have been scanned in colour with a HP Scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Negative staining of a non-haemadsorbing strain of African swine fever virus

Since the application of negative staining, preceded by fixation, prevents the disruption and distortion of the capsid of the African swine fever virus, improved contrast and evaluation of the appearance and size of virus particles in the electron microscope is possible and, in addition, the icosahedral shape of the virus is demonstrable. The mature virus particle contains at least 2 capsid layers and an outer envelope.The articles have been scanned in colour with a HP Scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Light and electron microscopic observations on the development of Babesia bigemina in larvae, nymphae and non-replete females of Boophilus decoloratus

In Boophilus decoloratus infected by transovarian passage with B. bigemina, primary schizogony occurred as a continuous repetitive process in all 3 stages of the tick's life cycle spent on the host. The primary schizonts and the large merozoites (= vermicules) produced by them were observed in the gut epithelium, haemocytes, muscles and peritracheal cells. Secondary schizogony which led to the formation of small merozoites (= infective forms) occurred mainly in the salivary glands, but was also observed in the cortex of the synganglion. Mature small merozoites were observed in nymphal and adult ticks only. An infective stabilate was prepared from nymphae collected on Day 14 and Day 15 post larval infestation. The infections resulting from intravenous injection of the stabilate had a prepatent period of 8 days.The articles have been scanned in colour with a HP Scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

The isolation and cultivation of calf rotavirus in the Republic of South Africa

Calf rotavirus was cultivated and propagated in tissue culture from faeces of 3-week-old calves suffering from severe diarrhoea. Criteria for viral involvement were: production of cytopathic effects in primary foetal calf kidney cells, specific fluorescence, and identification of the agent by means of electron microscopy. In a limited serological survey the majority of the cows on an infested farm were found to possess neutralizing antibodies to the local rotavirus strain.This article has been scanned in colour with a HP Scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-Format

Morphological variation in ephemeral fever virus strains

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Electron microscopic studies on corriparta virus

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Purification and physico-chemical characterization of Ecbo-virus type SA-I

Ecbovirus type SA-l, a bovine enterovirus, has been purified and crystallized and its chemical composition, physical characteristics and morphology studied. The virus particles have a mean diameter of 230Å, a sedimentation constant of 152S, a diffusion constant of approximately 1.7 x 10⁻⁷ cm² sec⁻¹ and a particle weight of about 6.1 x 10⁶ daltons. Its capsid consists of a number of identical subunits, probably 32, arranged in icosahedral symmetry and enclosing the nucleic acid component which comprises about 30 per cent of the total weight. Infective ribonucleic acid could only be isolated from infected cells. It has a sedimentation constant of approximately 37S corresponding to a molecular weight of about 2 x 10⁶, and consists of single-stranded RNA. The presence of a small amount of infective double-stranded RNA could also be demonstrated. In its physical characteristics and appearance, therefore, the virus is practically indistinguishable from polio- and other enteroviruses. The small differences in size found by different authors for various enteroviruses are probably insignificant and due to experimental error.The journals have been scanned in colour with a HP 5590 scanner; 600 dpi. Adobe Acrobat v.11 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.ab201