Culture of sheep Chlamydia in a sheep fibroblast cell culture

Recent advances in the understanding of Chlamydophila pecorum infections, sixteen years after it was named as the fourth species of the Chlamydiaceae family

Chlamydophila pecorum found in the intestine and vaginal mucus of asymptomatic ruminants has also been associated with different pathological conditions in ruminants, swine and koalas. Some endangered species such as water buffalos and bandicoots have also been found to be infected by C. pecorum. The persistence of C. pecorum strains in the intestine and vaginal mucus of ruminants could cause long-term sub-clinical infection affecting the animal’s health. C. pecorum strains present many genetic and antigenic variations, but coding tandem repeats have recently been found in some C. pecorum genes, allowing C. pecorum strains isolated from sick animals to be differentiated from those isolated from asymptomatic animals. This review provides an update on C. pecorum infections in different animal hosts and the implications for animal health. The taxonomy, typing and genetic aspects of C. pecorum are also reviewed.

Experimental infection of pregnant ewes with Chlamydia pecorum

Pregnant ewes were infected in midpregnancy with three isolates of Chlamydia pecorum derived from the feces of healthy lambs from three different farms. Oral infection, alone or together with Fasciola hepatica, did not result in tissue invasion, since all placental and fecal samples were negative for chlamydiae. Intravenous infection resulted in placental infection in 16 of 18 ewes in that chlamydiae were cultured from placentas or vaginal swabs. Two ewes bore dead lambs after a shortened gestation time. The chlamydiae isolated were all C. pecorum. There were no significant differences between the weights of the lambs from the infected groups and those from uninfected control ewes. Most ewes showed no serological evidence of infection by the complement fixation test; therefore, it is unlikely that the enteric subtype of C. pecorum is responsible for the cross-reactions sometimes seen in flocks being tested for C. psittaci infection.

Isolation of faecal chlamydia from sheep in Britain and their characterization by cultural properties

Faeces samples were taken per rectum from sheep on 26 farms in England and Wales and examined for the presence of chlamydia by culture in McCoy cell monolayers. Thirteen of the farms were known to have had abortion outbreaks associated with Chlamydia psittaci (enzootic abortion) and 13 were free of this infection. The chlamydia isolated were characterized by cultural techniques. Chlamydia were isolated from the faeces of lambs on all 26 farms and the prevalence of infection varied form 5-50% on individual farms. There was no significant difference between the proportion of infected lambs on farms where enzootic abortion was present or absent. Lambs first showed infection when they were 3 months old and the prevalence rate of infection increased up to 9 months old. No chlamydia were isolated from the faeces of 316 adult ewes. The chlamydia were identified as enteric rather than abortion type and thus were C. pecorum rather than C. psittaci.

Studies on the early phase of the pathogenesis of ovine enzootic abortion in the non-pregnant ewe

The initial phase of infection of non-pregnant sheep by Chlamydia psittaci (ovis) was studied by inoculating naïve and previously exposed sheep by the oro-nasal and subcutaneous routes with the BS isolate of C. psittaci (ovis). Naive animals exhibited a marginal rise in temperature and seroconversion was detected by enzyme-linked immunosorbent assay (ELISA) as early as 9 days after inoculation. Chlamydaemia was detected using culture and an antigen detection ELISA. No faecal shedding of chlamydiae was detected in ewes kept up to 3 weeks after infection. Although chlamydial antigen was demonstrated in epithelial cells or lymphocytes in lungs, liver, spleen, kidney, abomasum, jejunum, tonsils and suprapharyngeal, mandibular, parotid and mesenteric lymph nodes of some of the naïve sheep using an ELISA and streptavidin-biotin and immunofluorescent staining techniques, the organism could not be cultured from these tissues. No chlamydial antigen was demonstrated in any of the tissues of the previously exposed sheep nor in uninoculated controls. It is concluded that previously infected sheep are capable of completely eliminating subsequent infection and that chlamydiae localize in a variety of tissues of infected naïve sheep, especially within epithelial cells and lymphocytes.