OCKELBO VIRUS (TOGAVIRIDAE, ALPHAVIRUS) NEUTRALIZING ANTIBODIES IN EXPERIMENTALLY INFECTED SWEDISH BIRDS

The ability of native Swedish birds to produce and maintain production of Ockelbo virus neutralizing (Nt) antibodies were evaluated experime ntally between 6 June 1990 and 27 July 1991. After experimental infect ion of 57 birds of the orders Anseriformes and Passeriformes with Ocke lbo virus, these birds were examined for Ockelbo virus Nt antibodies a t 5 days, and at 1, 3, 6, 9, and 12 mo after inoculation. One month af ter inoculation, Nt antibodies were more prevalent in birds with a det ectable viremia (100%, n = 22) than in non-viremic birds (65%, n = 26) . The Nt antibody prevalence varied over time among taxa; detectable a ntibodies occurred earlier after inoculation and for a longer time in Anseriformes than in Passeriformes. By 5 days after inoculation, antib odies could be detected in 22 (71%) of 31 Anseriformes but in none of 16 Passeriformes. However, at 1 mo the antibody prevalences at 1 mo we re similar: 84% among the Anseriformes and 73% among the Passeriformes ; at 3 mo the prevalences were 50% in Anseriformes and 15% in Passerif ormes. Forty-two percent of the Anseriformes had detectable antibodies even 12 mo after inoculation.