Serotyping of chlamydial clinical isolates from birds with monoclonal antibodies

Forty-nine avian chlamydial strains, isolated mainly from various regions i n France and from different species of birds, were analyzed and tested with a panel of nine monoclonal antibodies (MAbs) by the indirect microimmunofl uorescence rest (MIF). The MAbs included five serovar-specific MAbs, three MAbs raised against Chalmydia psittaci and Chlamydia pecorum ovine strains, and one genus-specific MAb. Of the 49 isolates, 41 came from parrots or bu dgerigars; the rest were from pigeons, a canary, a duck, and a dove. Two ad ditional strains were from unknown hosts. Most of these avian strains were successfully serotyped according to their reactions with five serovar-speci fic MAbs by the MIF test. The serovars of 44 strains were determined: 39 we re of serovar A, 3 of serovar B, and 2 of serovar E. The remaining five iso lates were unclassified because they did not react with any of five serovar -specific MAbs but did react with genus MAb or the MAbs produced with ovine strains. The five unclassified isolates (two from budgerigars, two from Ga bon gray parrots, and one from a duck) indicate that one or more additional serovars of C. psittaci exist in birds. The heterogeneity within each subg roup was evident because the 49 avian isolates gave 10 subgroups when the r esults of the five serovar-specific MAbs were combined with results from th e three MAbs produced with ovine strains. This heterogeneity of the serovar isolates, as shown by the combination of MAbs, could provide strain marker s very useful for epidemiologic studies.