SYNERGISTIC ACTION OF HEMOPHILUS INFLUENZAE SUIS AND THE SWINE INFLUENZA VIRUS ON THE CHICK EMBRYO. II.

Blood cultures of embryos killed by the synergistic action of swine influenza virus and Hemophilus influenzae suis are consistently negative, and embryos infected with swine influenza virus may be killed both by filtered extracts of frozen and dried Hemophilus and by suspensions of heat-killed bacteria. The addition of Hemophilus to the chorioallantoic membrane of embryos infected with swine influenza virus causes the virus to spread from the membrane to the allantoic fluid and embryo. This spreading effect also obtains when a purified preparation of hyaluronidase is used instead of Hemophilus, but it is unaccompanied by a comparable increase in mortality.

THE COURSE OF EXPERIMENTAL INFECTION OF THE CHICK EMBRYO WITH THE VIRUS OF EQUINE ENCEPHALOMYELITIS.

The titration curve for the virus of Eastern equine encephalomyelitis inoculated into the 10 day old chick embryo shows that the maximum increase in virus content continues until shortly before the generalized destruction of the embryo is apparent. This is followed by a stationary phase. Histological studies of infected embryos fail to demonstrate selective tissue destruction, and titrations show the virus to be distributed throughout the egg, although concentrated in the embryo.

SYNERGISTIC ACTION OF HEMOPHILUS INFLUENZAE SUIS AND THE SWINE INFLUENZA VIRUS ON THE CHICK EMBRYO.

The synergistic effect of Hemophilus influenzae suis and swine influenza virus in the pig can be reproduced by the inoculation of these agents on the chorioallantoic membrane of 9 to 10 day old chick embryos. Two strains of human influenza virus that were studied failed to substitute for the swine virus in the synergistic reaction. No loss of synergistic effect was noted when the swine influenza virus was put through 11 chick embryo passages.

EXPERIMENTAL INFECTION OF THE CHICK EMBRYO WITH THE VIRUS OF PSEUDORABIES.

The chick embryo responds to experimental infection with the virus of pseudorabies with a disease pattern simulating the natural infection. Virus lesions of the membrane are followed by infection of all tissues of the central nervous system. Fixed strains produce a hemorrhagic destruction of the central nervous system of the embryo, which is referable to destruction of blood vessel endothelium.

EXPERIMENTAL GONOCOCCUS INFECTION OF THE CHICK EMBRYO.

1. The reaction of the chick embryo to nine strains of gonococci was studied. Four of these were inoculated intra-amniotically in 14 to 15 day embryos.