Clinal differentiation and putative hybridization in a contact zone of Pinus ponderosa and P. arizonica (Pinaceae).

The widely distributed Pinus subsection Ponderosae is a species complex that has a transition zone among taxa in the southwestern United States. In southern Arizona and New Mexico at least two recognized taxa, Pinus ponderosa var. scopulorum and Pinus arizonica or P. ponderosa var. arizonica, are known to coexist in close proximity. In this study, we report the existence of populations where the taxa are sympatric. One of the key characteristics distinguishing taxa is the number of needles per fascicle; P. ponderosa typically has three, P. arizonica has five. We examined the spatial distribution of needle-number types in a belt transect that covers a transition zone from nearly pure three-needle types at the top of Mount Lemmon to five-needle types downslope, in the Santa Catalina Mountains, Arizona. The spatial distribution is inconsistent with there being both free interbreeding among types and selective neutrality of types. Trees with intermediate types, having combinations of three, four, and five needles and/or mean numbers of needles between 3.0 and 5.0, are spatially concentrated in the middle of the transition zone. The spatial distribution supports the occurrence of hybridization and introgression, and this is consistent with reported crossabilities of the types. The results suggest that selection is acting, either on needle number per se or on other traits of the ecotype with which it may be in linkage disequilibrium, to maintain the observed steep clinal differentiation.

Chlamydiosis in captive white-winged doves (Zenaida asiatica).

Chlamydia psittaci was isolated from the spleen of a moribund white-winged dove (Zenaida asiatica). The isolate was serotyped as the serovar B that is commonly isolated from pigeons. A fourfold increase in the titer of antichlamydial IgM activity occurred in that bird in paired serum samples tested by chlamydial elementary body agglutination (EBA) and a greater than or equal to fourfold decrease of IgG occurred by direct complement fixation (DCF). The increases or decreases of EBA and DCF titers in other clinically ill birds that were treated with tetracycline varied, as normally occurs in cases of avian chlamydiosis. Titers in clinically normal birds were consistent with past infections. These birds were from a captive group of about 200 birds to be used for breeding and reproduction research. A small sample of recently caught wild birds was serologically negative for chlamydial antibody activity.

Usefulness and limitations of three serologic methods for diagnosing or excluding chlamydiosis in birds.

Diagnostic serology by use of elementary body agglutination is the most useful serologic method for diagnosis of chlamydiosis in birds, because it detects only IgM activity. A titer of 10 in budgerigars, cockatiels, and lovebirds and of > or = 20 in other types of birds is interpreted as being indicative of current infection. Latex agglutination, with detects IgM and IgG activity, may be useful in detecting large changes in titer. Direct complement fixation, detecting only IgG activity, is usable to detect past infection whenever elementary body agglutination and latex agglutination titers are < 10. Limitations of serologic results necessitating additional confirmatory testing are lack of titers in the acute phase of disease and diagnostic titers in clinically normal birds with low-grade chronic infections and in birds with prolonged maintenance of titers. Additional suggested examinations are chlamydial culture by use of choanal/oropharyngeal swab samples, WBC count, determination of hepatic-associated enzyme activity, chlamydial ELISA by use of the aforementioned swab samples, and additional serologic testing.

Comparison of procedures to detect Chlamydia psittaci antibodies in cockatiels (Nymphicus hollandicus).

Diagnostic serologic procedures for psittacine chlamydiosis were evaluated using experimentally inoculated cockatiels (Nymphicus hollandicus). Chlamydia psittaci was recovered from subjects on day 16 postinoculation. Seroconversion was confirmed by the direct complement fixation (DCF) test. The blocking enzyme-linked immunosorbent assay was demonstrated to be the most sensitive of three serodiagnostic procedures evaluated from inoculation until day 24 postinfection, with 92% sensitivity and 73% specificity. The DCF test was progressively more sensitive over the duration of the experiment, attaining 100% sensitivity and specificity on the day 24 postinfection. This study confirms the ability of the DCF procedure to adequately detect C. psittaci antibodies. Limitations relating to reproducibility of serologic results under clinical conditions found in this study indicate that a further refinement of tests is required to consistently detect and quantify antibodies.

Diagnostic serologic testing of cage and aviary birds for chlamydiosis and suggested confirmatory testing.

A 2 x 2 contingency table was constructed to demonstrate the relationships between detectable chlamydial antibody activity and clinical health status of tested birds. The table revealed that 65.5% of clinically ill birds were antibody positive by elementary body agglutination (EBA) (> or = 10 titers) and 59.0% were antibody positive by latex agglutination (LA). Thus, EBA was slightly more sensitive than LA in detecting antibody activity. Of the clinically normal birds, 96.7% were antibody negative (< 10 titers) by EBA and 98.3% were antibody negative by LA. Individual serum or plasma samples from a group of mixed types of psittacine birds and cockatiels were tested as a separate group, and relationships between EBA-detectable antibody activity and health status were obtained from a 2 x 2 contingency table. Sixty-six percent of birds clinically ill with signs of chlamydiosis in the mixed-type group were antibody positive, whereas only 32.3% of clinically ill cockatiels were antibody positive. Statistical analysis of the contingency table using a chi-square test demonstrated that the EBA test differentiates between individual birds on the basis of health status (P < 0.001). When testing paired serum or plasma samples by EBA, LA, and direct complement fixation (DCF), the highest percentage of significant (> or =4-fold change) titer decreases was detected by LA, and the highest percentage of significant titer increases was detected by DCF. Examples of EBA, LA, and DCF titers in paired and multiple serum or plasma samples are presented to show the variety of responses that can occur. Results reflected variations seen in individual testing of birds with titer variability seen in the first sample tested. Additional types of testing believed necessary for confirming or ruling out an infectious process in birds are outlined. The current interpretations of serologic results are given.

Elementary body agglutination for rapidly demonstrating chlamydial agglutinins in avian serum with emphasis on testing cockatiels.

The development and use of a stained chlamydial elementary body agglutination (EBA) antigen for detecting antibody activity in avian sera is described. Examples of serologic results on serum samples from various types of birds indicate the usefulness of EBA, latex agglutination (LA), and direct complement fixation (DCF) in diagnosing avian chlamydiosis. Results of tests on 10 cockatiels examined in clinics indicate that a combination of serology, culture, and/or antigen-detection enzyme-linked immunosorbent assay may be helpful when testing this type of bird. Agreement between EBA, LA, and DCF was 81.8% when testing 407 serum samples from cockatiels of unknown health status. The relationship between positive (> or = 10 titer) antibody activity and known health status of 77 cockatiels revealed that agreement between the two criteria was only 59.7%. Of 13 Chlamydia-inoculated cockatiels, seven birds seroconverted from negative to positive by EBA; five seroconverted by DCF. Only the five birds that seroconverted by both EBA and DCF were culture-positive for chlamydiae. None of 15 sham-inoculated control cockatiels developed detectable antibody activity, and none of 10 cultured were positive. In tests with column-separated IgM and IgG, EBA detected only IgM activity, LA detected IgM and IgG activity, and DCF detected only IgG activity.

Chlamydia latex agglutination antigen and protocol improvement and psittacine bird anti-chlamydial immunoglobulin reactivity.

Latex agglutination detection of chlamydial antibody activity in psittacine bird sera was significantly more sensitive when an improved protocol was followed than was a test using the previously used protocol. Titers of antibody-positive sera were fourfold to 32-fold higher by the improved protocol than titers by the previously used protocol, whereas antibody-negative sera were negative by both protocols. Column chromatography was used to separate immunoglobulins in psittacine bird serum. Immunoglobulin M was reactive in latex agglutination (LA) but non-reactive in direct complement fixation (DCF). Immunoglobulin G was reactive in LA and DCF. The fifth supernatant fluid of serum multiply absorbed with latex beads was non-reactive in LA and DCF. The immunoglobulins reactive in LA had high avidity and affinity for latex beads. Prolonged storage at 4 C to 6 C preserved LA reactivity of absorbed immunoglobulins better than storage at 21 C to 23 C.

Survey of clinical psittacine bird sera for Salmonella typhimurium agglutinins.

Of 2407 serum samples from various kinds of psittacine birds submitted for Chlamydia serology, 2343 (97.4%) were negative, 25 (1.0%) were equivocal, and 39 (1.6%) were positive for Salmonella typhimurium agglutinins. In additional serum samples from two groups of African gray parrots, the prevalence of agglutinins was 0.0% (0/38) in the Timneh variety and 24.0% (6/25) in the Congo variety. In sera from one macaw, one cockatoo, and one Amazon parrot, which were negative for chlamydial antibody activity, there were strongly reactive agglutinins for S. typhimurium. Two Amazon parrots had antibody activity against Salmonella and Chlamydia antigens.

Relationship between infectivity and cytopathology for L-929 cells, membrane proteins, and antigenicity of avian isolates of Chlamydia psittaci.

Seventeen isolates of Chlamydia psittaci from various avian species were examined. Based on their infectivity and cytopathology for L-929 cells, these isolates were separable into a high-infectivity group (HIG) and a low-infectivity group (LIG). Differences in the molecular weight of the major outer membrane proteins (MOMPs) of the isolates correlated with differences in infectivity. The HIG MOMPs had a molecular weight of 43,500, and the LIG MOMPs had a molecular weight of 45,500. The MOMP of one mammalian isolate of C. psittaci examined had a molecular weight of 43,500. Antisera raised against some of the isolates reacted with only the MOMP from isolates of their respective groups. The MOMPs of a mammalian C. psittaci isolate and of the C. trachomatis LGV 440 isolate did not react with HIG or LIG antisera. The MOMPs of some avian C. psittaci did react weakly with antiserum against the LGV 440 isolate of C. trachomatis.

Zoonoses acquired from pet birds.

The diagnosis, treatment, pathology, and epidemiology of psittacosis, the principal zoonotic disease contractible from birds, in human beings and in birds is discussed at length. Salmonellosis, toxoplasmosis, and allergic alveolitis are also considered. Several bacterial, viral, fungal, and parasitic organisms are mentioned as potential zoonoses.

Chlamydia psittaci latex agglutination antigen for rapid detection of antibody activity in avian sera: comparison with direct complement fixation and isolation results.

Cell-culture-grown Chlamydia psittaci of turkey origin was treated with phenol and partially purified by differential centrifugation. The most stable antigen/latex mixture occurred with crude antigen precipitated by dimethyl sulfoxide and digested with trypsin. Agglutination reactions occurred within 2 minutes when antigen/latex and antibody-positive serum mixtures were rotated to facilitate contact of the reagents. Nonspecific agglutination of control latex occurred with 1.2% of clinical sera. When C. psittaci was isolated from feces from individual birds, latex agglutination (LA) and direct complement fixation (DCF) together detected antibody activity (titers greater than or equal to 8) in significantly more cases than did DCF alone. It follows, then, that an LA titer alone is highly indicative of a currently active infection or one that has occurred only recently. The isolation rate from birds that had no antibody activity detectable by LA or DCF was 3.8%. In tests on paired clinical sera, LA and DCF agreed in 72.5% of the cases regarding increased, decreased, or stable titers. For detection of antibody activity in single sera, LA had a sensitivity of 39.1% and a specificity of 98.8% relative to DCF detection of antibody activity. The high specificity corroborates the usefulness of LA as an indicator of current or very recent infection.