Virus isolate 127 causing egg drop syndrome 1976 was purified and examined by electron microscopy. In CsCl equilibrium density gradients three bands could be visualised. Two bands at an apparent density of 1.32 g/ml, which could not be separated by fractionation, harboured high amounts of HA-activity and infectivity. Electron microscopic examination of these bands revealed particles of typical adenovirus morphology. The third band at a density of 1.30 g/ml consisted mainly of disrupted particles. This band showed a clear peak of HA-activity but no evidence of radioactivity and negligible amounts of infectivity.
369Summary Efficiency of indirect immunofluorescence microscopy (IFM) for detection ofM. pulmonis antibody (lgG) in rats was compared with results of enzymelinked immunosorbent assay (ELISA), complement fixation (CF), cultural isolation and histopathology. IFM was carried out on M. pulmonis infected BHK-21 cells grown on cover slips or multitest slides. After acetone fixaJion these antigen carriers could be stored at -20 C for several months so that serological tests could be done at any time and completed within 2 h. The IFM was strain specific and the sensitivity of the test was comparable with that of the ELISA, whereas the CF-test proved to be very insensitive. For routine monitoring, only in cases of fresh infections should time consuming cultural procedures be preferred to serological tests. Chronic disease stages were readily detected by histological examination.Diagnosis of mycoplasma infection can be achieved by a variety of direct and indirect procedures. While routine checks on laboratory rat and mouse colonies are usually carried out with cultural procedures, other techniques to identify Mycoplasma spp. are the growth-inhibition test (Clyde,
SummaryAir filter sets lclasses EU6 and EU9, or EU6 and S) were tested for their efficiency in protecting laboratory animals against potential airborne infections. Flexible-film isolators were used as a smaller scale model. In the first experiment, lasting 7 months, it was tested whether minute virus of mice (MVM) was able to penetrate the airfilters between one isolator containing experimentally infected mice and another with MVM negative mice. In the second experiment we tested whether microorganisms in the incoming air were able to penetrate air filter sets. To assess this gnotobiotic mice in an isolator were monitored for 9 months for changes of their microbial flora. In both experiments a combination of EU6 and EU9 air filters proved to be sufficient to maintain the microbiological status of the animals. The same combination of medium efficiency filters (EU6 and EU9) is used on the air supply to 4 SPF-barrier units in which infections with MVM occurred repeatedly soon after the initial stocking. After a thorough disinfection no reinfection has been detected to date. This demonstrates that the relatively low efficiency of the air filters was not the cause of the repeated infection. The procedure for disinfection is described.
Propagation of CELO virus employing confluent monolayers of chicken enbryo fibroblasts (CEF) yielded virus titers one to two logs lower than those from confluent chicken kidney (CK) cells. An enhancement of virus production in CEF as measured by plaque formation was obtainedby infectng cultures in the growing non confluent state. Measurements of 3H-thymidine incorporation revealed a positive correlation between the DNA synthesis of CEF cultures at the time of inoculation and the amount of progeny virus, whereas in the CK-CELO-system no such relation was observed. Requirement of replicative fibroblasts for CELO multiplication was also demonstrated by comparison of virus replication in synchronized stationary and serum stimulated CEF cells. In stationary CEF cells arrested in the G1 phase of the cell replication cycle by serum deprivation and infected withe CELO virs, no cytopathic effect could be observed, and only very low amounts of virus were produced. But 24 hours after release of these cells for growth by serum stimulation a logarithmic rate of virus multiplication and a complete CPE occurred. Infection of synchronized CEF cultures at different stages of the cell cycle revealed that CELO multiplication was correlated with the S phase of the infected cell. In synchronized CELO infected CEF cultures viral DNA synthesis started 12 to 14 hours after growth stimulation when cells were near the end of the S phase. In contrast, no viral DNA synthesis could be measured in growth arrested CELO infected CEF cells, when cellular DNA synthesis was low. Therefore not only production of infectious virus but also viral DNA synthesis is correlated with events during the S phase of the infected CEF cell.
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