Yolk Sac Inoculation Research Articles

A Comparison of Four in vitro Methods for the Isolation of the Pleuropneumonia-Like Organism of Chronic Respiratory Disease from Tracheal Exudate

IN a previous report8'9 on a study of methods of isolation of the pleuropneumonia-like organism (PPLO) associated with chronic respiratory disease (CRD), it was determined that an in vitro procedure held several advantages over other techniques. At that time a comparison was made of a modification of the Grumble's medium5, the yolk-sac inoculation method3'4, and solid medium cultivation. The first method not only yielded the largest number of isolations, but controlled bacterial and mycotic contamination most satisfactorily. Other advantages of this medium were speed, simplicity and economy. The work reported here involved a comparison of the modified Grumble's technique8,9 with methods outlined by Edward2, Adler1 and Lecce6.

Studies on herpes simplex virus in tissue culture. I. Characteristics of virus growth.

The Z strain of herpes simplex virus as well as three freshly isolated strains of the same virus caused a complete degeneration of the fibroblastic outgrowth in roller tube cultures of human embryonic lung. Infectivity titrations made in such tissue cultures regularly gave higher values than the lethality titers obtained by yolk sac inoculation of embryonated eggs. Furthermore, the virus amounts found in the fluid phase of roller cultures were comparable to those obtained in the allantoic fluid of eggs. Three strains of herpes simplex virus have so far been isolated directly in tissue culture from herpetic vesicles. However, more work is needed, involving isolation experiments from pathological specimens simultaneously in tissue cultures and other hosts before the relative sensitivity of the tissue culture method for primary isolation purposes can be evaluated.

Poliomyelitis. II. Propagation of MEFI strain of poliomyelitis virus in developing chick embryo by yolk sac inoculation.

Summary1. The MEFl-A strain of human poliomyelitis virus(10), after 119 serial passages in suckling hamsters, has been maintained in one passage series for 41 consecutive generations and in a second series for 38 generations in the developing chick embryo by the yolk sac route of inoculation. Both lines of passages are still in progress. 2. The identity of the chick embryo adapted virus with human poliomyelitis virus was established by mouse neutralization tests in which anti-Lansing type immune sera from 3 different sources were used; by the ability of the passage virus to stimulate the formation of antibodies in monkeys which neutralize known virulent strains of Lansing type poliomyelitis virus; and by the ability of monkeys to withstand intracerebral challenge with known virulent strains of poliomyelitis virus after they had survived inoculation with the chick embryo passage virus. The identity of the passage virus was further established by its ability to induce typical symptoms and histopathologic le...

The pathologic changes produced in chick embryos by yolk sac inoculation of group A coxsackie virus.

A series of embryonated eggs incubated from 6 to 18 days have been successfully infected by yolk sac inoculation with a strain of group A Coxsackie virus. The resulting pathologic changes are here described. The principal lesion consisted of widespread acute necrosis of striated muscle, apparently essentially identical in type and development with that characteristically produced by the virus in suckling mice. The infection was not itself lethal; some embryos with virtually complete destruction of skeletal muscle were found alive. The older the embryo at the time of inoculation, the less the severity and extent of the lesions; but susceptibility was sometimes not entirely lost in embryos 18 days old. Two embryos inoculated at this time hatched and lived for 4 and 11 days respectively. One showed minimal specific muscle lesions, and the other only some irregularity in muscle fiber size. The lessening of severity of the lesions was especially marked and abrupt in embryos inoculated on the 10th and the 12th day of incubation. In addition to the muscle lesions characteristic of infection with group A Coxsackie virus, there were regularly present in the more immature embryos extensive necrosis of epidermis and feathers and degeneration of feather follicles, believed to be probably a direct dermotropic effect of the virus infection. Other visceral lesions, chiefly liver necrosis, were occasionally observed but seemed not to have been due to direct virus action. As in suckling mice infected with group A Coxsackie virus, no lesions were observed in the central or peripheral nervous system nor in the heart muscle. No lesions deemed specific were seen in the few specimens of chorioallantoic membranes examined.

Studies on Chick Embryo Adapted Rabies Virus

Summary Four strains of rabies virus, one chick-brain fixed (Flury) and three street strains were adapted to the developing chick embryo. The Flury strain was passaged through 80 chick embryo generations by yolk-sac inoculation of infected chick embryo tissue. The virus multiplied slowly in the fertile hens' eggs and reached its maximal titer on the ninth to tenth day after inoculation. The virus was distributed throughout the egg, with possible exception of the allantoic fluid, the highest concentration being present in the embryo. Death of the infected embryos, inoculated at 7, 9 and 11 days of age, occurred as a rule immediately before or at the time of hatching. When 15-day or older fertile eggs were inoculated most of the embryos hatched but the virus was “carried over” to the newly hatched chicks causing either death or development of homologous antibodies in the survivors. The LD50 titer of infected embryo suspensions remained within the range of 10−4.50 to 10−5.50 for mice, guinea pigs, cotton rats and chicks throughout the cultivation period. The intracerebral titration of the Flury strain in rabbits yielded highly irregular results which were discussed in relation to the “self-sterilizing neuro-infection” phenomenon. The invasive power of the Flury strain for parenterally inoculated rabbits seemed to be entirely lost, and the virulence of the strain for hamsters and guinea pigs seemed to undergo some attenuation during the series of passages in the developing chick embryo.