• Korean Journal of Veterinary Research
• /
• v.1 no.1
• /
• pp.36-53
• /
• 1961

This experiment was conducted on the fowl pox embryo vaccine for the production immunity, and stability, using an attenuated fowl pox virus (Nakano strin). Burnet's window method was applied, that is, 0.1 ml. of seed virus was inoculated on the chorioallantoic membrane of 12-day old chicken embryos, and incubated for 5 to 6 day, and then the result were read. Four kinds of suspensions of different embyo tissue were prepared and tested for the infectivity in chickens. Finally the suspension of chorioallantoic membrane was used as the vaccine throughout the experiment. Results obtained in this experiment are summarized as follows: (1) Of embryo tissue infected with the vaccine virus, chorioallantoic membrane had the highest virus titer of $10^{-5.4}$ $EID_{50}$, and albumen the lowest titer of $10^{-0.7}$ $EID_{50}$. (2) Suspensions of infected whole embryo with or without saline, and de-embryonated whole egg had about the same virus titer of $10^{-4.4}$ $EID_{50}$, whereas the chorioallantoic membrane had $10^{-5.7}$ EID 50 or higher. The virus titer droped one log from $EID_{50}$ when inoculated into chickens. Takes were observed 35.6% of 500 chickens by stick method and 89% of 500 chickens by brush method. (3) The chorioallantoic membrane conferred almost perfect immunity for chickens by 10 days after vaccination. (4) Satisfactory immunity was observed in the chickens when eruption in a single follicle. (5) Eight of 10 vaccinated chickens revealed durable immunity for 307 days following vaccination. (6) The vacuum-dried vaccine maintained its infectiviy for 899 days at $5^{\circ}C$ or below and maintained the vius titer of $10^{-3.6}$ $EID_{50}$. On the other hand, non-desiccated wet vaccine maintained the titer of $10^{-3.0}$ $EID_{50}$ for 50 days of preservation period at $5^{\circ}$. However, in 50% glycerin-saline the infectivtiy of the same wet vaccine dropped to $10^{-1.5}$ $EID_{50}$ (7) The vartation of virus titer of the vaccine before and after desiccation was $10^{-0.5}$ $EID_{50}$ on the average. (8) As suspending media, 0.85 per cent saline and distilled water showed nearly the same effect on the infectivity of the vaccine by retaining the titer $10^{-3.0}$ $EID_{50}$ after 50 days of preservation both at $5^{\circ}C$ and $20^{\circ}C$, while 50 percent cent glycerine-saline dropped the titer to $10^{-2.5}$ EID and $10^{-1.5}$ $EID_{50}$ respectively at $5^{\circ}C$ and $2^{\circ}C$ after the same period.

• Korean Journal of Veterinary Research
• /
• v.15 no.1
• /
• pp.57-67
• /
• 1975

The poxvirus group is considered to be a typical cytoplasmic inclusion forming virus. Every poxvirus has been reported to produce only one kind of inclusion in the infected tissues. A vague concept that inclusions of poxviruses are eosinophilic or acidophilic has prevailed. Although many papers and theories about the nature of the inclusion have been presented, most of them are not quite convincing on the point of the relations with virus multiplication, and an analysis of papers published showed that there seem to be many discrepancies in the descriptions of the nature of the poxvirus inclusions. Comparative studies on host-virus interaction with cowpox, orf, swinepox and fowlpox viruses which selected from each Group (I-IV) of poxviruses were performed from the morphological and virological standpoints. At first, in cowpox virus-FL cell system, as a comparative model, cytoplasmic inclusion, nucleic acid metabolism by autoradiography and detection of viral antigen by immunofluorescence were studied and obtained the results as follows: 1. The focus-like cytopathic effect (CPE) at early stage developed to entire culture at terminal stage of infection, and also the developing status of CPE was correlated to viral doses for inoculation. Two kinds of cytoplasmic inclusions which named A and B type were easily observed by Giemsa, hematoxylin-eosin (H & E) and May-Greenwald Giemsa (MGG) stainings in the infected cells. The B type inclusions were formed at early stage of infection and the A type inclusions were produced subsequently the B type formation. The B type which common type inclusion in poxviruses was a small compact or aggregate at early stage and developed to a large diffuse body at terminal stage of infection. On the other hand, the A type inclusion which depend upon the kind of virus was appeared as round and discrete shape, and its size and number was increased gradually during the culture period. It was characteristic to form distinct halos around the both types of inclusions in acid fixed, H & E stained preparations of infected cultures. The B type inclusion was always positive in Feulgen reaction and showed as DNA containing body but the A type inclusion was not. 2. In the relationship between inclusion and DNA metabolism of infected cells by the qualitative autoradiography using 3H-thymidine, the appearance of silver grains was coincided with B type inclusion but not with A type inclusion. This showed that the DNA synthesis was proceeded in all B type inclusions except those in the terminal stage with a diffuse form. This suggested that the B type inclusions are only sites of DNA synthesis and this was proceeded after the cell infection independently. The activity of DNA synthesis of the inclusions was nearly the same as that of the nucleic of normal cells and non-inclusion bearing cells. and non-inclusion bearing cells. Regardless of the size of the degree of DNA synthesis of the B type inclusion, inclusion bearing cells all showed remarkable suppression of nuclear DNA synthesis. 3. By the direct fluorescent antibody technique viral antigen in infected cells was detected. The B type inclusions have been proved to contain a great deal of viral antigen, whereas the basic substance of A type inclusion did not show antigenicity except the round edge. It was suggested that the round edge fluorescence might be caused by the glare of cytoplasmic viral antigen which pushed out and concentrated by the A type inclusion development. 4. Hemorrhagic red pock formations on chorioallantoic membrane of embryonated chicken egg had proved the characteristic of used viral strain. 5. By the above studies on the nature of two types of inclusions and the role they play in virus multiplication, it was concluded that the B type inclusion must be the site of the synthesis of viral DNA and protein as well as the site of the virus.