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SUMMARYThe effect of interferon (IFN) on infection and maintenance of persistent infection of Borna disease (BD) virus in cell cultures was investigated. Acutely BD virus-infected primary rabbit brain and rat lung cells produced significant levels of interferon detectable 3 days post-infection in the culture supernatants. Rat brain and rat lung cells persistently infected with BD virus produced only moderate levels of IFN over a long period. In contrast, persistently infected Madin-Darby canine kidney (MDCK) cells did not produce detectable amounts of IFN. Exogenous homologous IFN completely inhibited the expression of BD virus antigen in acutely infected rabbit brain cells, when added during the first 24 h after infection. IFN added later (2 to 6 days post-infection) reduced virus titres to different degrees depending on the onset of treatment. However, IFN added to persistently infected rat lung cells did not appear to influence the degree or quality of BD virus antigen expression or the intracellular amount of infectious virus. Two facts indicate that IFN is not involved in the establishment or maintenance of persistent BD virus infection in ritro. Thus, MDCK cells, which could not be induced to produce IFN, can be readily persistently infected with BD virus in vitro, and exogenous IFN did not appear to influence persistent BD virus infection.

Im Rahmen der Studie zeigten in der Routine eingesetzte Endoskope und Optiksp?lflaschen kaum mikrobiologische Beanstandungen, w?hrend die Luft-/Wasser- und Absaugventile vergleichsweise hohe Keimbelastungen aufwiesen. Anhand von begleitenden Frageb?gen wurde der Schulungsbedarf zur Aufbereitung von Ventilen und zur Verwendung von Reinigungsb?rsten deutlich.

In order to study whether the latency of herpes simplex virus (HSV) is immunologically controlled, the influence of different immune mechanisms on the in vitro-reactivation of the virus in latently infected lumbosacral ganglia of mice was investigated. Combined addition of macrophages and antibodies to cultures of ganglionic tissue proved most effective in delaying virus reactivation. This was achieved to a lesser degree when applying antibodies only, whereas macrophages alone were not effective, nor were immune lymphocytes, nor was interferon from L-cells or from the peritoneal cavity of mice.

The virological safety of medicinal leeches has to be ensured prior to their use on patients. While leeches can be kept and bred under standardized conditions, feeding them horse blood adds a non-standardized component, which poses some risk of infection of the treated patients. Here, we investigated the speed at which blood-borne viruses are degraded by the microbial flora in the leech intestine, in order to define the safety of the product and the length of the necessary quarantine period prior to its administration to patients. Feeding blood was spiked with bovine viral diarrhea virus (BVDV), reovirus, and murine parvovirus (10(7) ID₅₀ ml(-1)). The virus titer in the intestinal contents of the leeches was determined using permissive cell cultures and compared to that of the original virus titer at the following time points: immediately after feeding; after 3, 14, and 30 days; and monthly thereafter until the 7th month. The BVDV titer was below the detection limit of 10(1) TCID₅₀ ml(-1) after 3 months, while reovirus and murine parvovirus titers were undetectable after 4 months. No positive virus findings were obtained at later time points. Thus, when fed the blood of vertebrates, the finished product "Medicinal leech, Hirudo verbana" can be considered virologically safe if the animals are maintained at 20 °C, which corresponds to their natural habitat conditions and ensures a high metabolic rate. Therefore, after the last feeding, a quarantine period of 4-6 months and appropriate care at room temperature, which supports microbial degradation and digestive processes, are recommended.