-Nine rats (16.4%) out of 55 (Rattus norvegicus) from cattle farms were seropositive to Neospora caninum. Two of the seropositive rats were also PCR positive but all were negative by immunohistochemistry and PAS staining. The brains of all the captured rats were homogenized and initially inoculated intraperitoneally into nude mice or into SPF ICR mice, which had been immunosuppressed with prednisolone. One mouse that was inoculated with brain material from a seropositive rat became infected with N. caninum, as demonstrated by the presence of a tissue cyst in the brain and confirmed by immunohistochemistry and PCR. This is the first finding of N. caninum in naturally infected farm rats. The findings show that natural N. caninum infection occurs in wild brown rats and thus rats may serve as a reservoir for the protozoan on the cattle farm. Neospora caninum / rat / cattle farm / natural infection

ABSTRACT. This study is to (1) investigate the prevalence of Chlamydophila abortus infection in cows and goats in Taiwan, and (2) compare the genetic properties of Taiwanese isolates with abortion strains from other sources. Approximately 71% of aborted cows and 58% of aborted does had IgG against C. abortus in their sera. The seroprevalence rate in cows may be overestimated, because a certain degree of cross-reactivity with C. pecorum cannot be ruled out. Only 22.7% (from aborted cows) and 33.3% (from aborted does) of vaginal swabs that tested positive by polymerase chain reaction led to successful isolation of C. abortus by inoculation into chicken embryos, equivalent to 7.1% and 7.9% of isolation rates, respectively. The major outer membrane protein gene of 15 Taiwanese abortion isolates was compared with that of various strains by restriction fragment length polymorphism (RFLP) and nucleotide sequencing. Restriction enzyme CfoI was able to distinguish Taiwanese ruminant isolates, which have identical RFLP patterns, from C. felis (feline) and C. psittaci (avian) strains. Taiwanese isolates had 98.8-100% homology with known ruminant abortion strains and were phylogenetically closest to bovine LW508 strain. KEY WORDS: bovine, caprine, Chlamydophila abortus infection, major outer membrane protein gene, RFLP.

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Epizootic abortion in goats has been frequently reported in Taiwan since 1993. The outbroken flocks were found in most of districts in Taiwan. No apparent clinical signs were found in aborted doe. The typical abortion occurred in the last two months of pregnancy. The incidence of abortion was from 10% to 87% in outbroken farms in 1993, and a total of 976 out of 2130 pregnancies (46%) were found abortion in our investigation. Gross lesions in aborted fetuses included generalized haemorrhage and swollen liver. Chlamydia psittaci was isolated from tissues of aborted fetuses and from vaginal swabs of aborted does. Chlamydial antibodies were detected among 67% to 100% of aborted does from epizootic flocks. The C. psittaci was diagnosed as the causal agent in enzootic abortion. This is the first report on chlamydial isolation and antibody surveys in epizootic abortion in goats in Taiwan.

The nucleotide sequences of the S‐RNA of Akabane viruses JaGAr‐39, OBE‐1, Iriki and the newly isolated PT‐17 strains and the Aino virus were determined and compared. The results reveal that the S‐RNAs of the four Akabane strains share 96.9% homology in nucleotide sequences. Only one amino acid difference out of the 233 amino acids of the nucleocapsid protein (N) and three amino acid differences in the 91 amino acids of the nonstructural protein (NSs) were found among the Akabane viruses. Amino acid sequences of N and NSs proteins of the Aino virus have approximately 80% identity as compared with the Akabane viruses. The results also demonstrate that the four Akabane viruses and the Aino virus can be clearly differentiated by RFLP (restriction fragments length polymorphism) analysis using RT‐PCR generated nucleocapsid protein genes and digested with HaeIII and HindIII. The phylogenetic tree based on the UPGMA (Unweighted Pair Group Method with Arithmetic Mean) analysis of the sequences of nucleocapsid protein genes and the S‐DNAs revealed that the newly isolated PT‐17 strain is most closely related to Iriki strain, than the JaGAr‐39 or OBE‐1 strains.