1. Inapparent infection was called forth in M. rhesus monkeys by means of subcutaneous inoculation of ETBE virus. 2. Viremia was found in 18 (86 per cent) of 21 monkeys. In all the 18 monkeys, specific virus-neutralizing antibodies were found; in 17 of them complement-fixing antibodies developed in addition. 3. Neutralizing antibodies (N greater than or equal to 1.7 log10) were first recorded on 10th day with a peak on 32nd day, retaining, after a small decrease, a relatively high level in all reacting animals. 4. Complement-fixing antibodies were first found on 18th day, showing a peak on 22nd day whereafter they dropped considerably or even disappeared so that on 150th day they were present in a low titre in only 35 per cent of the originally reacting monkeys. 5. The findings were compared with the situation in naturally infected humans and in hamsters infected inapparently (experimentally) with ETBE virus.

Animals↗

PubMed1977

Viremia and serum antibodies in Syrian hamster after inapparent infection with European tick-borne encephalitis virus.

1.) Adult Syrian hamsters (Cricetus auratus) are relatively insusceptible to the lethal affect of the ETBE virus after peripheral inoculation. After subcutaneous infection with 10(3) i. cer. mouse LD50 of the virus they manifest 25 per cent mortality. 2) In subcutaneously infected hamsters the virus is demonstrable in the CNS of only 20 per cent of the animals. CF- and VN-antibodies can be found in the blood from the 10th day; CF--antibodies culminate on the 20th-30th day receding relatively quickly, whereas VN-antibodies peak after the 28th day, dropping only partly and persisting. 3) The dynamics of CF- and VN-antibodies and a high number of clinically inapparent hamster infections resemble the situation in humans infected with ETBE under natural conditions.

Animals↗

PubMed1976

A note on single- and two-dose immunogenicity tests of inactive virus vaccine in chicks.

Single dose extinction limit test ot inactive polio vaccine in chicks lasts 4 days and offers the same results as the two-dose test which requires 14 days. When "long-term" incubation instead of "conventional" 2 hours-incubation of the serum/virus mixtures in the neutralization reaction was used, extinction limit values higher by 0.6-0.7 log10 were regularly obtained.

Animals↗

PubMed1976

[Pathological findings in experimental monkeys (author's transl)].

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Animals↗