Swine chlamydiosis is Chlamydia psittaci-caused contagious disease characterizing abortion, still birth and death of a number of newborn piglets in perinatal period (Milon et al., 1983; Bortnichuk, 1989; Qiu et al., 1998, 1999, 2000; Sachse et al., 2004).

On the pig farm in Longyan City, Fujian province, in the east of China, in order to prevente abortion, pig herds have been inoculated classical swine fever vaccine, Japanese encephalitis vaccine, pig parvovirus vaccine and pseudorabies virus vaccine annually. But some of pregnant sows aborted or labored partial dead fetuses with fetal membranes with a lot of white rice-like granules (Figure 1). For knowledge of the problem, 30 pig sera were sampled for detecting the antibodies against Chlamydia psittaci using IHA for animal chlamydiosis and the result of test was 12 serum samples were positive for chlamydial antibody (the antibody titer 1:16 ~ 1:64), and the chlamydia infection rate reached 12/30 (40.0%). 
 

Figure 1 There are a lot of white rice-like granules in fetal membranes of a partial aborted fetuses

In June 2006, we sampled two stomach contents and five fetal membranes, two of which have a lot of white rice-like granules in them, from aborted fetuses on the pig farm in Longyan City, for detecting Chlamydia sp. by means of nested polymerase chain reaction (nested-PCR) developed by us. 

The two sets of primers for C. psittaci MOMP gene used in nested-PCR are:

The primer pair No.1:
MP1: 5’-ATGAAAAAACTCTTGAAATCGGCA-3’
MP2: 5’-TTAGAATCTGAATTGAGCATTCATGTG-3’

The primer pair No.2:
MP3: 5’-CAGGATACTACGGAGATTATGTTT-3’
MP4: 5’-GATTAGATTGAGCGTATTGGAA-3’

The result of the seven aborted pig samples examined by nested-PCR are seen Figure 2.
 

Figure 2 The result of the seven aborted pig samples examined by nested-PCR for Chlamydia sp. DNA

 
From the Figure 2, we know that the MOMP gene fragments which correspond with the expected that in size (488 bp), were obtained from 1/2 aborted pig fetus’s fetal membranes with a lot of white rice-like granules (the sample No.3), 2/2 aborted pig fetus’ stomach contents (the samples No.4 and No.5), and 2/3 aborted pig fetus’s fetal membranes without any white rice-like granules (the samples No.6 and No.7).

On the basis of the results of the serological test and PCR, it was confirmed that chlamydiosis existed in swine herds on the pig farm in in Longyan City, Fujian province. But while pregnant sows were infected by chlamydia, white rice-like granules pathologic change may appear or may not appear in aborted pig fetus’s fetal membranes. Formation of white rice-like granules in placenta may be related with chlamydia infection time. How do the pathologic changes occur will be studied further.

In some literature on pathological changes of fetal membrane of pig chlamydial abortion, it was described that fetal membranes of pig chlamydial abortion showed black-red colour with water-like material covering on them and there necrotic focus in the mucous membrane face of placenta and edema around the necrotic focus (Pienaar et al., 1975; Yang, 1982 and 1984), but no recording same as that mentioned above.

Acknowledgement
The test was subsidized by The national Fun (2008FY210200).

References
Milon A., Geral M.F., Pellerin J.L., and Lautie R., 1983, Chlamydiosis in animals, Rev. Rhum. Mal. Osteoartic, 50(11): 727-731

Bortnichuk V.A., 1989, Significance of the immunofluorescence reaction in the diagnosis of swine chlamydiosis, Mikrobiol. Zh., 51(3): 65-68

Qiu C.Q., Zhou J.Z., Gao S.D., Cheng S.M., Duan Y.J., Li Y.C., Chen G.H., and Yang X.L., 1998, Monitoring swine chlamydiosis on intensive pig farms in six provinces of China, Chinese Journal of Veterinary Science and Technology, 28(10): 3-5

Qiu C.Q., Zhou J.Z., Gao S.D., and Cheng S.M., 1999, Monitoring of swine chlamydiosis in intensive pig farms：diagnosis of abortions in sow herds on a breeding pig farm in Fujian province, Chinese Journal of Veterinary Science and Technology, 29(11): 8-10

Qiu C.Q., Cheng S.M., Zhou J.Z., Gao S.D., Duan Y.J., Pan S., 2000, Assay of swine chlamydiosis in intensive pig farms, Chinese Journal of Veterinary Medicine, 26(3): 23-24

Sachse K., Grossmann E., Berndt A., Schutt C., Henning K., Theegarten D., Anhenn O., and Reinhold P., 2004, Respiratory chlamydial infection based on experimental aerosol challenge of pigs with Chlamydia suis, Comp. Immunol. Microbiol. Infect. Dis., 27(1): 7-23
http://dx.doi.org/10.1016/S0147-9571(02)00079-6

Pienaar J.G, and Schutte A.P., 1975, The occurrence and pathology of chlamydiosis in domestic and laboratory animals: a review, Onderstepoor J. Vet. Res., 42(3): 77-89

Yang Y., 1982, Preliminary report of swine chlamydiosis research, Hubei Journal of Animal and Veterinary Medicine, (2): 2-4

Yang Y., and Jiang T., 1984, Artifical infections of pigs using Chlamydia psittaci, Hubei Journal of Animal and Veterinary Medicine, (1): 22-23