Angela E.R. Taylor

The Development of Dirofilaria immitis in the Mosquito Aedes aegypti

1. The developmental stages of D. immitis in the mosquito A. aegypti at 26°C. have been followed in living and fixed preparations, and the fates of the cell groups of the microfilaria have been traced. 2. The larvae spend the first six or seven days inside the distal cells of the Malpighian tubules; during the next six days they inhabit the lumen of the tubules and eventually migrate to the head of the mosquito on the fifteenth to seventeenth day. 3. The “nuclear-column“ cells contribute largely to the formation of the oesophagus of the infective larva. 4. The G cells 1–3 produce the intestine and the G4 cell forms the anal plate and then the rectum. 5. The anal pore ultimately becomes the anus.

Maintenance of filarial worms in vitro.

1. 1. Adult Litomosoides carinii have been maintained in vitro for 23 days and the females have produced microfilariae for 18 days. The cultures were kept at 37 °C in a medium containing fresh rat serum and Parker 199. The average numbers of microfilariae produced by female L. carinii, per day, in vitro, ranged from 1,000 to 8,600, in different experiments. 2. 2. Adult Dirofilaria immitis have been maintained in vitro for 8 days but the females continued the production of microfilariae for only the first two days. 3. 3. Microfilaria immitis, Mf. loa and Mf. bancrofti have survived in culture for from 10 to 14 days; the G cells 1 and 2 of Mf. loa divided under these conditions. 4. 4. Infective larvae of D. immitis remained alive and healthy for 9 days in vitro. They moulted during this time but did not increase in size.

Studies on the Microfilariae of Loa loa, Wuchereria bancrofti, Brugia malayi, Dirofilaria immitis, D. repens and D. aethiops.

(1) The microfilariae of L. loa, W. bancrofti, B. malayi, D. immitis, D. repens and D. aethiops have been studied in detail, using phasecontrast and ultra-violet microscopy and vital staining techniques.(2) In these microfilariae the cells of the “oten Mundgebilde” have been renamed “hook-muscle cells” as they appear to be concerned with the movements of the hook.(3) Two cells have been demonstrated in the nerve ring by means of ultra-violet photomicrography and vital staining with rongalit methylene blue.

The spermatogenesis and embryology of Litomosoides carinii and Dirofilaria immitis.

1. Phase-contrast, ultra-violet and fluorescence microscopy have proved useful tools in the study of the embryology of filarial worms. 2. Spermatogenesis in L. carinii has been described for the first time for any filarial worm. 3. The spermatozoa of L. carinii and D. immitis are remarkable in that they contain well defined chromosomes. 4. The development of the ovum to the mature microfilaria has been described for both L. carinii and D. immitis. 5. Staining with acridine orange has demonstrated the cellular distribution of deoxyribonucleic acid (green fluorescence) and ribonucleic acid (red fluorescence) in both living and fixed embryos of each species.

Some properties of the immunogens (protective antigens) of a single variant of Trypanosoma brucei brucei.

SUMMARY: Column-separated, clean trypanosomes were subjected to nitrogen cavitation and ultracentrifugation (90 min, 99000 g); the supernatant contained most of the immunogens but a few remained in the well washed residue. Column chromatography yielded a strongly immunogenic protein fraction (SAF1), small doses (0·035 mg protein/dose × 4) of which protected mice against a maximum challenge of 5 × 104 of the homologous variant organisms for a minimum of 17 weeks. No heterologous (variant or strain) protection was obtained with SAF1 either with increased doses or by homologous challenge followed by heterologous challenge 3 weeks later. Disc electrophoresis of SAF1 showed four anodic components intermediate in mobility between α-macroglobulin and transferrin of normal rat serum. Analytical ultracentrifugation indicated a substantial proportion of 6·5S protein together with 3·0S and 1–1·5S proteins. A smaller soluble antigen fraction (SAF8) consisted of 2·0S protein but preliminary experiment has not shown it to be immunogenic. Infected rat plasma separated after 6 h was as effective as SAF1 in protecting mice against homologous challenge whereas rapidly separated infected rat plasma gave only slight protection. Two identical precipitinogens were detected in infected rat plasma and SAF1 by immunodiffusion. Three additional precipitinogens were present in SAF1 and one other in the infected rat plasma. Antisera raised against various trypanosome fractions, including SAF1, agglutinated the homologous trypanosomes but to a lesser extent than antisera to living trypanosomes. Incubation of trypanosomes in either SAF1, or infected rat serum or plasma decreased their infectivity which was not altered by 8 h of incubation in normal rat plasma.

Observations with the ultropak microscope on microfilariae of Litomosoides carinii circulating in the liver of a cotton-rat, before and after the administration of Hetrazan

Abstract Microfilariae of L. carinii were observed circulating in the peripheral capillaries of the liver of an infected cotton-rat by means of the Leitz Ultropak microscope. The mf. could be clearly seen as white snake-like organisms, offering little resistance to the blood flow. After intravenous administration of Hetrazan, the majority of mf. adhered, generally by their tails, to the capillary walls and sometimes a leucocyte was also found attached to the tail.

The effect of antifilarial drugs on the embryonic development of Litomosoides carinii, of the cotton-rat.

Abstract 1. 1) Filarial worms (Litomosoides carinii) have been exposed to various drugs in vivo or in vitro and the effect upon the developing embryos has been studied. 2. 2) Compounds of arsenic and of antimony (Pentostam and K.324) appeared to destroy all the developmental stages and to affect all parts of the cell equally. 3. 3) Cyanine 863 affected the nucleus in particular and appeared to be concentrated here. 4. 4) The bis iso quinolinium compounds caused a more generalized degeneration within the cell. They acted mainly on the early embryos and caused little damage to the mature microfilariae. 5. 5) Diethylcarbamazine had no effect on the embryos of L. carinii.

The effect of paraminobenzoic acid, parahydroxybenzoic acid and riboflavin on Plasmodium gallinaceum in chicks

Abstract 1. (1) Plasmodium gallinaceum developed at a subnormal rate in chicks fed on a purified basal diet which was deficient in paraminobenzoic acid and parahydroxybenzoic acid. 2. (2) The addition of either paraminobenzoic acid or parahydroxybenzoic acid to the basal diet in low concentrations (0.005 per cent.) produced an increase in parasitaemia. Higher concentrations (0.1 – 0.5 per cent.) of paraminobenzoic acid resulted in an infection lower than that of the chicks fed on the basal diet, whereas high concentrations of parahydroxybenzoic acid had no suppressive effect. 3. (3) Parahydroxybenzoic acid in low or high concentration antagonized the suppressive effect of high concentrations of paraminobenzoic acid. 4. (4) Chicks fed on a diet deficient in riboflavin developed a markedly lower parasitaemia than did those chicks fed on a diet rich in this substance. 5. (5) These experiments indicate that small amounts of riboflavin, paraminobenzoic acid and parahydroxybenzoic acid are required in the diet of chicks, to allow P. gallinaceum to develop normally. Large amounts of paraminobenzoic acid are inhibitory to the parasite, possibly because they interfere with the utilization of parahydroxybenzoic acid.