Embryonated eggs

Thiopheneglyoxal has been found to be only moderately active against Newcastle disease virus and influenza virus in embryonated eggs. ... 

A standardized viral suspension is exposed, in the presence of yeast suspension, to appropriate dilutions of disinfectant in WHO hard water. At appropriate times, dilutions are made in inactivated horse serum and each dilution is inoculated into tissue cell culture or embryonated eggs (as appropriate for the test virus). The drop in infectivity of the treated virus is compared with that of the control (untreated) virus. 

Without appropriate antibiotic treatment, fatality rates can approach 100%. The causative agent of epidemic typhus is Rickettsia prowazekii. Typhus vaccine consists of a sterile aqueous suspension of killed R. prowazekii which has been propagated in either yolk sacs of embryonated eggs, rodent lungs or the peritoneal cavity of gerbils. 

Nematodes are long, cylindrical unsegmented worms that are tapered at both ends. Because of their shape, they are commonly referred to as roundworms. Some intestinal nematodes contain a mouth with three lips, and in some the mouth contains cutting plates. Infection occurs after ingestion of embryonated eggs or tissues of another host that contain larval forms of the nematodes. 

Cell culture is the predominant and indispensable tool for virus isolation and cultivation infectivity assays and vaccine production and testing. Although some viruses are more easily isolated in animals and embryonated eggs, the modem era of virology only began when Enders et al. (1949) showed that poliovirus was able to reproduce in various kinds of human embryonic cells in culture whereas in vivo its multiplication is largely restricted to the neurons in the grey column of the spinal cord. 

Fig. 7.13. Influence of wavelength on the hatching of the embryonated eggs of Diphyllobothrium lattim. (After Grabiec et at., 1963.)...

Stage 7 Oncosphere formation. Characterised by the appearance, in the uterus, of embryonated eggs containing fully formed hexacanth embryos. 

To verify in vitro results, we have also developed an in vivo assay for L. dispar PTTH (52, Thyagaraja et al, in preparation). This assay is comparable to larval assays develop for Af. sexta (56 and B. mori (58) and uses last instar female larvae. Neck ligation prior to day 7, the day when a small pre-peak in hemolymph ecdysteroid titer appears, blocks further development. Injection of PTTH-containing extracts posterior to the ligation, including post-embryonic egg extract, reinitiates development and subsequent pupation. Attempts to develop an in vivo assay comparable to the pupal-adult B. mori assay (5B were unsuccessful, since brain removal as close as 15 min post-pupal ecdysis failed to block L. dispar female adult development (Thyagaraja et a/., unpublished results). 

Inoculate 10-d-old embryonated eggs with the vims at approx 10-100 pfu/egg. 

Young eggs, 1- to 4-hour-old contain negligible MH activity (17), whereas older embryonated eggs, 24- to 44-hour-old ( ) or 48- to 64-hour-old (17), have relatively high molting hormone titer. 

Since all viruses are obligate parasites, suitable living hosts in the form of either intact animals, embryonated eggs, or cell cultures are essential to detect and measure their viability in the laboratory. This need for a living host adds considerably to the expense and time when assessing the activity of topicals against viruses. 

The use of experimental animals in testing the activity of chemical germicides in general against viruses is considered neither necessary nor desirable [21]. Established and well-characterized cell lines are the recommended host system. In some cases, such as when working with adenoviruses [22], it is advisable to carry two cell lines one for the preparation of virus pools and the other to assay for its infectivity. The use of embryonated eggs may be needed in rare cases, such as for the production of high-titered pools for influenza viruses. 

Of 41 arylglyoxal /V,/V-disubstituted hydrazones tested against influenza PR8 in embryonated eggs at the maximum tolerated dose only two compounds (LXI), were active [238],... 

Figure 2. Trichuris suis adult male (cf) and female (9)worms. The insert shows a microscopic embryonated egg which is the form ingested by patients.

Observe embryonated eggs under illumination in a dark room, and mark an injection point about 0.5 mm above the chrioallantoic membrane (Fig. 2). Disinfect the eggs with tincture of iodine, and puncture at the point marked. 

DeSomer, P., Prinzie, A., and Schonne, E., 1959, Infectivity of poliovirus ribonucleic acid for embryonated eggs and unsusceptible cell lines. Nature 184 652. 

Subsequently, similar small viruses have been found associated with bovine, avian, and canine adenoviruses (Luchsinger et al., 1970 Dutta and Pomeroy, 1967 Yates et al, 1972 Domoto and Yanagawa, 1969). It would appear that any adenovirus can serve as a helper for AAV infection in any cell which is permissive for the adenovirus. For example, a chicken adenovirus will permit human AAV to productively infect either chick embryo fibroblasts or embryonated eggs (Blacklow et al, 1968). 

Kethoxal, 3-ethoxy-2-oxobutanal hydrate [CH3. CH(OEt).CO.CH-(OH) ] was the first substance, selectively, to inactivate complete virions, namely those causing Newcastle bird disease and influenza tested in embryonated eggs (Tiffany et al, 1957). 2-Thiouracil 12,44) a potent inhibitor of the reproduction of plant viruses, also decreases the infectivity of poliovirus by reaction with a mercapto-group in the capsid (Steele and Black, 1967). However agents such as these which act on the complete virion have not yet proved clinically successful. 

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