Biological properties of Aujeszky's disease (pseudorabies) virus strains with special regard to interferon production and interferon sensitivityLomniczi, B.
doi: 10.1007/BF01240608pmid: 4837359
The avirulent strain KF of Aujeszky's disease (pseudorabies) virus had a 10 to 100 times lower growth ability in chick embryo fibroblast cells than the virulent strain and it formed scarcely visible plaques, if any. Infection of permanent pig kidney cells (PK15) with avirulent strains resulted in higher virus yields than the virulent strain and easily visible, small plaques (0.5 mm) arose. The virulent strain formed plaques about 2 mm in diameter in both types of cells. The avirulent strains were not neuropathogenic for the chick, whereas the virulent strains showed a distinct neurovirulence. The avirulent strains stimulate a small amount of interferon in chick embryo fibroblast cultures from about 30 hours after infection and are 5–10 times more sensitive to interferon than the virulent strains.
Studies on the mechanisms of influenza virus infection in hamster trachea organ cultureSchiff, L.
doi: 10.1007/BF01240607pmid: 4209454
Tracheal organ cultures of 4-day-old, 2-, and 4-week-old Syrian hamsters infected with influenza A/PR/8 virus were studied. Ciliary activity in infected explants from 4-day-old and 2-week-old hamsters declined rapidly after five days and by the 13th day was virtually undetectable. Cultures from 4-week-old hamsters showed a similar but slower effect. Histological sections of infected explants showed distinct cytopathologic changes which preceded ciliostasis. The columnar structure of the ciliated respiratory epithelium in all infected tracheal tissue became flattened and was eventually destroyed. When influenza A/PR/8 virus was added to whole tracheal explants from 4-day-old hamsters, approximately 70 per cent of the virus adsorbed in the first 30 minutes, and 90 per cent of the total adsorbed within 2 hours. Explants from 2- and 4-week-old hamsters adsorbed influenza virus at a much slower rate. Growth curves indicated that tracheal cultures from all three age groups support replication of A/PR/8 virus. Explants from 4-day-old hamsters yielded a maximum titer of 103.75HAD50/ml by the 9th day after injection; cultures from 2- and 4-week-old hamsters yielded a 5 and 15-fold lower infectivity titer. Interferon was demonstrated in infected cultures from the three different age groups in comparable concentrations.In vivo studies indicate that 4-day-old hamsters have a greater susceptibility than 2- and 4-week-old hamsters to hamsters-adapted influenza A/PR/8 virus. Observations from cultures of young suckling hamster tracheas indicate this model system will be useful in further investigations of tissue specificity in influenza viral infections.
Saponin adjuvantsDalsgaard, K.
doi: 10.1007/BF01240612pmid: N/A
An aqueous extract of the saponin drugQuillaja saponaria Molina was separated by a combination of gel exclusion and ion exchange chromatography. Some of the fractions were investigated for adjuvant activity in guinea pigs. The guinea pigs were immunized against foot-and-mouth disease virus serotype 0, and adjuvant activity was estimated as an increase in serum neutralizing antibodies and in resistance to challenge with homologous virus. Only one fraction showed adjuvant activity and this was confirmed in cattle. The animals were immunized with a stock vaccine foot-and-mouth disease serotype 0 of the Frenkel type and adjuvant activity was estimated as an increase in serum neutralizing antibodies. The fraction was subjected to thin-layer chromatography, polyacrylamide gel electrophoresis, and analytical ultracentrifugation. These analytical techniques indicated that only one substance was present in the fraction. It was shown that this substance in aqueous solutions was present in a micellar state above a certain critical micelle concentration.
An electron microscopic study of the intracellular development of echovirus 22Jamison, R.
doi: 10.1007/BF01240606pmid: 4209453
The replicative cycle of echovirus 22 in tissue cultures of African green monkey kidney cells has been studied by electron microscopy. Although virus particles were seen only in the cytoplasm, infection of the cell caused distinctive nuclear pathology. A well-defined cytoplasmic inclusion body could be demonstrated. Throughout the replicative cycle, the virus particles were intimately associated with membranous elements. In some cases the virus appeared to exit from the cells enclosed in membranous structures.
Comparison of maternal and cord serum titres for measles and for rubella antibodiesBrouwer, R.; Groot, I.; Verheij, F.
doi: 10.1007/BF01240611pmid: 4209455
Measles and rubella hemagglutination inhibiting (HI) antibodies were assayed in 100 paired maternal and cord sera. The geometric mean titre of the cord sera was significantly higher than the geometric mean titre of the maternal sera, for both measles and rubella. The rubella mean titre was significantly higher than the measles mean titre. The mode of delivery of the neonate did not influence the relative concentration of antibodies in paired sera. These results suggest that there is active placental transport of IgG antibodies against measles and rubella.
Isolation of reovirus type 1 from lambs showing respiratory and intestinal symptomsBelák, S.; Pálfi, V.
doi: 10.1007/BF01240605pmid: 4365602
The first isolation of reovirus type 1 from lambs is reported. The virus was isolated from the nasal and rectal swabs of lambs with respiratory and enteric disease. In the course of the epidemic two phases were observed, the first characterized with relatively mild clinical symptoms and followed by a secondary bacterial complication. The isolated virus is most likely to play a role in inducing the disease. The virus was isolated on foetal lamb kidney cells by inoculating both outgrown cell monolayers and cell suspensions. The latter method was more successful. The isolate was characterized by its cytopathic effect, morphology, resistance to heat, chloroform, sodium deoxycholate, saponin and trypsin and by its heat stability in the presence of divalent cations. Serologically it proved to belong to reovirus type 1.