One hundred and sixty nine Escherichia (E.) coli strains isolated from fecal samples of aquatic birds in Geumho river basin and Dalseong park were tested by agar dilution method to determine their susceptibility patterns to 14 antimicrobial agents. The distribution of tetracycline resistance determinants (tetA, tetB, tetC, tetD and tetE) were also examined by PCR in 76 tetracycline-resistant (TC∨r) E. coli isolated. The high resistance was observed in tetracycline, cephalothin and ampicillin (45.0~36.7%). Resistance of E. coli isolates derived from Dalseong park to tetracycline, cephalothin, ampicillin and streptomycin (65.7~44.8%) were significantly higher than those isolated from Geumho river basin (31.4~14.7%). About seventy percent (70.4%) of the strains isolated were resistant to one or more drugs tested. Thirty (39.5%) of 76 TC∨r E. coli isolates which were resistant to one or more drugs transferred all or a part of their resistance patterns to the recipient strain of E. coli J53 by conjugation. All of TC∨r E. coli isolates contained at least one or more of 5 tet genes examined. The most common genes found in these isolates were tetA (60.6%) and followed by tetB (7.9%) and tetC (1.3%). However, tetD and tetD and tetE were ant found in any of the isolates tested. Twenty one (27.6%) of TC∨r E. coli isolates had two determinants, tetA/tetB (20 strains), tetA/tetC (1 strain). And two strains (2.6%) contained three determinants (tetA/tetB/tetC).

This study was performed to detect Neospora caninum in blood of 61 Korean native cattle and 50 dairy cows in Chungnam province. All of them were healthy and did not show any clinical signs. DNA was isolated from blood samples and a 328 bp fragment was amplified by PCR using primer pair Np21 and Np6. The PCR positive rate was 14.8% in Korean native cattle and 0% in dairy cows. Cows with 15.6% were a little higher than bulls with 12.5% in gender. The detection rate of over 3-year-old Korean native cattle was 28.6% in age. The results demonstrate that N. caninum DNA can be detected in blood by PCR. PCR analysis in blood may be useful to annually screening test for N. caninum infection in clinically healthy cattle.

Rhipicephalus appendiculatus serpin-3 (RAS-3), R. appendiculatus serpin-4 (RAS-4) and a 36kDa immuno-dominant protein of R. appendiculatus (RIM36) were reported as candidate antigens for the anti-tick vaccine to control ixodid ticks. In the present study, we generated recombinant proteins of RAS-3 (rRAS-3), RAS-4 (rRAS-4) and RIM36 (rRIM36), and assessed their potency as an anti-tick cocktail vaccine in cattle model. RT-PCR analysis showed that RAS-3, RAS-4 and RIM136 transcripts were detected in both adult male and female ticks during feeding. Immunization of cattle with the combination of rRAS-3, rRAS-4 and rRIM36 had raised antibodies against all recombinants and anti-sera had reacted with the molecules from the tick salivary gland extract. Tick infestation challenge demonstrated protective immunity against female ticks, resulting in mortality rates of 39.5 and 12.8 % for the vaccinated and control groups, respectively. Moreover, the mortality rate of Theileria parva-infected female ticks was 48.5 and 10.8 % in the vaccinated and control group, respectively. In order to evaluate the levels of pathogen transmission capacity by T. parva-infected ticks fed on immunized cattle, the occurrence of T. parva in the bovine parotid lymph node and peripheral blood was also determined and quantified by real-time PCR. Although the infection with T. parva could not be protected by the vaccine, the occurrence of pathogen in peripheral blood was delayed 1 to 2 days after the infestation challenge in vaccinated group. These results suggest that this cocktail vaccine plays a role in the prevention of tick infestation.

Bovine nasal and oral discharges were used as samples for bovine viral diarrhea virus (BVDV) gene detection. Viral genes in serum (S), nasal discharge (N) and oral discharge (O) were quantified with real-time polymerase chain reaction using SYBR Green by the relative quantification method, and findings were compared among samples. Although the quantity of the BVDV gene in S was greater than those in N and O, all samples were available to identify persistently infected (PI) cattle with BVDV by reverse transcription polymerase chain reaction (RT-PCR). The swab samples were able to be stored for a few days at 4degC with a little decrease of amplification signal in RT-PCR. Oral swab sampling was easier than nasal swab sampling, and was also less uncomfortable for the cattle than other sampling methods without pain or unnecessary retention. This sampling method can be performed without any special technique and equipment. Therefore, the oral swab sampling method is useful for screening to detect BVDV PI cattle by RT-PCR.

There were studied the most effective methods of diagnostics of genital forms of clamidiosis at cows in pregnancy, calving and the postnatal period. The description is resulted and the estimation is given methods of laboratory diagnostics, serological methods, a method of light microscopy, immunofluorescence, enzyme immunoassay, chlamydia allocation method on laboratory models, complement linkage reaction, hemagglutination reaction, a method of polymerase chain reaction. As a result of complex use of reaction of complement linkage reaction, on the basis of the analysis of clinical and histologic research, studying of a condition of immune system and nonspecific resistance of an organism it is possible to carry out successfully diagnostics of genital forms of clamidiosis at cows. | Целью исследований явилось изучение наиболее эффективных методов диагностики генитальной формы хламидиоза у коров в период беременности, ca и послеродового периода. Приведено описание и дана оценка методам лабораторной диагностики, серологическим методам, методу световой микроскопии, иммунофлюоресценции, иммуноферментному анализу, методу выделения хламидии на лабораторных моделях, реакции связывания комплемента, реакции гемагглютинации, методу полимеразной цепной реакции. В результате комплексного использования реакции связывания комплемента (РДСК), на основании анализа клинических и гистологических исследований, изучения состояния иммунной системы и неспецифической резистентности организма можно успешно проводить диагностику генитальной формы хламидиоза у коров.