Serological evidence of morbillivirus infection in polar bears (Ursus maritimus) from Alaska and Russia

Abstract

One-hundred-and-ninety-one samples of blood serum collected from 186 polar bears (Ursus maritimus) between 1987 and 1992 were analysed for morbillivirus antibodies. The samples were collected in the Bering, Chukchi and East Siberian seas. Sixty-eight samples (35.6 per cent) had morbillivirus antibody titres > 5; the percentage of positive samples ranged from 26.2 to 46.2 per cent from year to year. The proportions of adults, sub-adults and cubs which were seropositive were 43.9, 35.7 and 37.9 per cent respectively. Some seropositive dams had seronegative young and some that were seronegative had seropositive young. One litter of two cubs, in which the dam was seronegative, had one seropositive and one seronegative cub. Seropositive bears occurred in all the areas from which the samples were collected but there was a significantly greater incidence in the bears sampled in Russia. The high prevalence of seropositive bears over the period suggests that the bear morbillivirus is endemic in these regions of the Arctic, but its source is unknown.

Antibodies to Canine Distemper and Phocine Distemper Viruses in Polar Bears from the Canadian Arctic

“…Antibody prevalence in polar bears from the Chukchi Sea population was also greater in adults than in juveniles and similar between sexes (Follmann et al, 1996), but antibody prevalence in juveniles was higher than that found in the present study (ϳ37% vs. 5% for both Canadian populations). Although the significance of this difference is unknown, it is important to note that the number of samples available for serology from juvenile bears in the present study was small (22 out of 200 samples) and was therefore possibly too few to estimate prevalence accurately.…”

“…Furthermore, repeated exposure seems unlikely, given that nine bears tested seronegative at first capture and remained seronegative up to 5 yr later. This persistence of antibody titers was also observed in some bears from the Chukchi Sea population over a period of 2 yr (Follmann et al, 1996). However, antibody titers may not always persist-one bear from each of the Chukchi Sea and WH populations tested seropositive at first capture but seronegative at second capture.…”

“…However, with considerable variation in prevalence rates among years for each population (LS, 0-22%; WH, 14-44%) and with a relatively small number of samples collected on a per year basis (Յ37 per year), the significance of a difference between populations remains questionable. Similarly, Follmann et al (1996) found considerable year-to-year variation in the prevalence of antibody to morbillivirus in polar bears from the Chukchi Sea population (26-42%), but, again, the number of samples collected per year was generally small (Յ44/yr).…”

“…Antibody to morbillivirus was identified in polar bears from western Alaska (USA) and eastern Russia (Follmann et al, 1996). However, the results of differential serum neutralization assays showed this antibody to be more specific to canine distemper virus (CDV) than to phocine distemper virus (PDV), dolphin morbillivirus (DMV), or porpoise morbillivirus (PMV) (Garner et al, 2000), and CDV-neutralizing antibodies have not been found in serum samples collected from pinnipeds inhabiting the same areas (Osterhaus et al, 1988).…”

Pathogenesis of Two Strains of Lion (Panthera leo) Morbillivirus in Ferrets (Mustela putorius furo)

“…4,9,11,12,20,30 Sources of confusion regarding the host range of CDV in felids have arisen from disparate reports of the lack of CDV disease in domestic cats and the occurrence of fatal CDV-like disease in captive and free-roaming large felids. 4,[8][9][10][26][27][28]31,34,37,45 The debate regarding CDV interspecies transmission (canid to felid) versus the existence of a unique feline morbillivirus strain antigenically related to CDV has not been fully resolved.…”