Dominance of Chlamydia psittaci-specific IgG2 subclass in the humoral immune responses of naturally and experimentally infected cattle

Prevalência de anticorpos anti-Chlamydophila spp. em propriedades rurais com histórico de aborto bovino no estado do Paraná

Chlamydophila abortus é o agente etiológico do aborto epizoótico bovino, cujas manifestações clínicas mais freqüentes são aborto, nascimento de bezerros prematuros e de animais fracos, natimorto e repetição de cio em intervalos irregulares. O objetivo deste trabalho foi estimar a prevalência de anticorpos anti-Chlamydophila spp. em fêmeas bovinas de propriedades rurais com histórico de aborto, selecionadas dentro do delineamento amostral do Plano Nacional de Controle e Erradicação da Brucelose e Tuberculose no estado do Paraná. Foram testadas pela prova de fixação de complemento 3.102 amostras de soro de fêmeas bovinas (idade > 24 meses), provenientes de 373 propriedades. Ao total, 44 (1,42%) animais foram positivos com títulos > 32. A prevalência de focos foi de 8,82% (6,15%-12,17%). Animais confinados ou semi-confinados (OR=3.339, P=0.004), propriedade com menos de 35 matrizes (OR=3.339, P=0.017), presença de produtos do aborto na pastagem (OR=2.372, P=0.037) e aluguel de pasto (OR=3.398, P=0.006) foram considerados fatores de risco para Chlamydophila spp. A infecção por Chlamydophila spp. acometeu um número pequeno de animais, oriundos de propriedades com histórico de aborto. A importância deste agente como causa de aborto em bovinos no estado do Paraná, se existir, é muito pequena.

An investigation into the role of Chlamydophila spp. in bovine upper respiratory tract disease

An outbreak of upper respiratory tract disease was investigated in a group of 17 housed home-bred calves on a mixed dairy, beef and sheep farm in Devon. Conjunctival swabs were collected and tested for Chlamydophila spp. DNA using a PCR test that detects Chlamydophila abortus and Chlamydophila psittaci. Six of the calves tested gave a positive result. Further epidemiological observations and laboratory testing indicated that the adult dairy cows, from which the affected calves originated, were the most likely source of infection.

Production, reproductive, and metabolic factors associated with chlamydial seropositivity and reproductive tract antigens in dairy herds with fertility disorders

While chlamydial infections cause abortions in cattle, its role in other reproductive disorders is uncertain. This study identified the risk factors for chlamydial infection in herds with history of subfertility. We investigated the possible effects of coinfections, different metabolic parameters, abortion, ovarian cysts, pathological vaginal discharge, length of the open period, milk yield, housing conditions and age. In cows from 34 farms with elevated reproductive disorders, 41.5% had antibodies against chlamydia, while chlamydia antigen was detected in the vagina and uterus of 46.7%. A statistical relationship between seropositivity and antigen positivity was not found. Abortion (OR = 6.6) and loose housing (OR = 2.3) were risk factors for the presence of chlamydia antibodies. Furthermore, there were significant relationships between metabolic disorders and chlamydial infections. Increased levels of beta-hydroxybutaric acid (OR = 6.8) and hypocalcaemia (OR = 6.0) often accompanied chlamydia antigen in the vagina. Increased age (OR = 1.2) and pathological vaginal discharge (OR = 2.4) were identified as risk factors for chlamydia antigen in the vagina. The largest risk factor was for the association of ovarian cysts (OR = 21.5) with uterine antigen. In conclusion, chlamydial infection in dairy herd cows is best understood as a multifactorial disease.

Reinfection with Chlamydophila abortus by uterine and indirect cohort routes reduces fertility in cattle preexposed to Chlamydophila

This study investigated the effects of controlled reinfection on fertility of cattle naturally preexposed to Chlamydophila abortus. All animals had high prechallenge levels of immunoglobulin M (IgM), IgG, IgG1, and IgG2 serum antibodies against ruminant C. abortus in a chemiluminescent enzyme-linked immunosorbent assay. Twenty virgin heifers were estrus synchronized with prostaglandin F2, artificially inseminated 2 to 3 days later, and challenged immediately by intrauterine administration of 0, 10(4), 10(5), 10(6), or 10(8) inclusion-forming units (IFU) of C. abortus. Ten heifers were estrus synchronized, inseminated, and uterine challenged 2 weeks later. These animals were also indirectly exposed to C. abortus infection (cohort challenged) by contact with their previously challenged cohorts. Pregnancy was determined by rectal palpation 42 days after insemination. All anti-C. abortus antibody isotypes increased in heifers following uterine challenge with 10(8) IFU. A total of 11, 83, 50, 66, and 0% of heifers were pregnant after uterine challenge with 0, 10(4), 10(5), 10(6), and 10(8) IFU of C. abortus, respectively. A total of 50 and 65% of heifers were pregnant with and without cohort challenge, respectively. Uterine inoculum dose and cohort challenge (or, alternatively, a negative pregnancy outcome [infertility]) correlated highly significantly with a rise in postchallenge anti-C. abortus IgM levels over prechallenge levels. Logistic regression modeled fertility, with uterine challenge dose and cohort challenge or prechallenge IgM as predictors (P < 0.05). The models predict that the uterine C. abortus inoculum causing infertility is 8.5-fold higher for heifers without cohort exposure and 17-fold higher for heifers with high IgM levels than for heifers with cohort exposure or with low IgM levels.

Quantitative detection of Chlamydia psittaci and C. pecorum by high-sensitivity real-time PCR reveals high prevalence of vaginal infection in cattle

Bovine vaginal cytobrush specimens were analyzed for the presence of Chlamydia spp. by a high-sensitivity, high-specificity quantitative PCR. The 53% prevalence of low-level Chlamydia psittaci and C. pecorum genital infection detected in virgin heifers suggests predominantely extragenital transmission of Chlamydia in cattle and conforms to the high seroprevalence of anti-Chlamydia antibodies.

Association between Chlamydia psittaci seropositivity and abortion in Italian dairy cows

Although the seroprevalence of Chlamydia psittaci is widespread in Italian dairy herds, its role in inducing genital disorders has not been elucidated. We therefore set up a case-control study to compare seroprevalence to C. psittaci in an aborted-cow population and in a randomly selected control group in the province of Parma (the Po Valley of northern Italy). The true seroprevalence (45%) in aborted cows was significantly higher than that in the control group (24%) (adjusted odds ratio=2.53).

Purification of Chlamydia psittaci antigen by affinity chromatography on polymyxin B agarose for use in the enzyme-linked immunosorbent assay (ELISA)

The purification of cell wall antigens of Chlamydia psittaci by affinity chromatography on polymyxin B agarose is described. Chlamydial cell wall antigens were prepared using different methods: heat treatment, ultrasonication and sodium deoxycholate treatment. The antigens were subsequently purified by gel chromatography. The highest amount of cell wall antigens was obtained by heat treatment of the chlamydiae at 90 degrees C and pH 8.5. The purified antigens showed molecular weights of 450 kDa to 700 kDa. Treatment of heat-extracted antigens with trypsin, pronase E or proteinase K did not destroy antigenic activity or alter the molecular weight. On the other hand, potassium metaperiodate treatment led to a significant decrease of both. Chlamydial cell wall antigens extracted by heat treatment and purified by affinity chromatography were used as ELISA-antigen. Using this ELISA and the complement fixation test (CFT), a total of 576 bovine sera was tested. 92 of these sera reacted positively in the ELISA and only 13 in the CFT. In addition, the prepared ELISA was compared with a commercial ELISA. 12 out of 15 sera tested were positive when using the ELISA described and 10 were positive when using the commercial ELISA.

Enzyme-linked immunosorbent fluorescence assay and high-pressure liquid chromatography for analysis of humoral immune responses to Coxiella burnetti proteins

A microtiter enzyme-linked immunosorbent fluorescence assay based on alkaline phosphatase conjugate and 4-methylumbelliferyl phosphate as fluorogenic substrate was developed and adapted to quantitatively analyze immunoglobulin G subclass 1 (IgG1) and IgG2 responses of vaccinated and infected cattle to proteins of Coxiella burnetii. The enzyme-linked immunosorbent fluorescence assay surpassed the conventional enzyme-linked immunosorbent assay with a 50-fold-higher sensitivity and a broader range of linear dose-response signals. Antigens of C. burnetii were purified by sodium dodecyl sulfate extraction and molecular-sieve high-pressure liquid chromatography. The purified 14-, 27-, and 30-kilodalton proteins were used as antigens without any further treatment. Vaccination with either chloroform-methanol-extracted cell residues of C. burnetii or the 27-kilodalton major surface protein evoked an early IgG2 response to the 27-kilodalton protein (2 weeks after immunization), whereas IgG2 to lipopolysaccharides of C. burnetii was detected only in the late phase (13 weeks after immunization). These results may have implications for the serodiagnosis of acute and chronic Q fever. IgG1 against these antigens was induced solely by naturally occurring C. burnetii infections, indicating that infected cattle can be distinguished from vaccinated cattle by using the enzyme-linked immunosorbent fluorescence assay and SP27 antigen.

Q fever vaccines for animals

The results of different workgroups and those obtained in own investigations with Q fever vaccines for cattle and sheep are reviewed and discussed. In field trials Coxiella (C.) burnetii vaccines of inactivated whole cells (WC) in phase (ph) I as well as WC ph II vaccines prevented infections of cows exposed to naturally infected environments, provided they were vaccinated as noninfected calves. To monitor calves for this purpose the sensitive ELISA has superseded the complement fixation test (CF). WC ph I vaccines failed to prevent shedding by uninfected cattle and sheep which were vaccinated and subsequently challenged by parenteral inoculation with viable organisms, but reduced shedding, and prevented pathological lesions and clinical symptoms. The results obtained in field trials with a commercially available vaccine consisting of killed WC ph II of C. burnetii and inactivated WC of Chlamydia psittaci indicated that vaccination had significantly improved fertility in vaccinated herds. However, the mechanism of protection is unclear because the function of the chlamydial component in this vaccine is not yet defined. Cattle given this vaccine can be distinguished from naturally infected cattle because the former produce predominantly non-complement-binding IgG2, detectable by ELISA. This vaccine frequently causes undesirable local reactions. Antigens of C. burnetii (strain "Frankfurt", ph II) prepared by propagation in cell cultures and successive purification by guanidinium hydrochloride- and chloroform/methanol-extraction (CMR), as well as a major protein extracted from these CMR preparations represent potential vaccine candidates without such side effects.

Specific interaction of bovine IgG1 and IgG2 subclasses with different chlamydial antigens

Antigens of the immunotype 1 strain B-577 of Chlamydia psittaci, which were separated by SDS-PAGE and electrophoretically transferred to nitrocellulose membranes were used to probe sequential serum samples of cattle with experimentally induced or naturally occurring chlamydial infections. Applying IgG1- and IgG2-specific markers in an enzyme immunoassay procedure, a predominance of IgG2 reactions with different proteins was determined. The interaction of IgG1 with antigens such as the genus-specific lipopolysaccharide and the major outer membrane protein was usually limited to periods immediately following overt clinical disease. Some other antigens like the 60,000 and 62,000 D proteins, for example, were recognized by both subclasses over the entire period of investigation. This indicates that it may be possible to determine the phase of infection through analysis of the IgG1 and IgG2 responses with the Western blot technique. The different IgG1 and IgG2 responses of cattle infected with different strains of Chlamydia psittaci as well as the diverse reactions of cattle from different herds with naturally occurring chlamydial infections further indicate that it may be feasible to distinguish the strains causing these chlamydial infections using different antigens in the Western blot technique. The results obtained by this method may have implications for the production of a subunit vaccine as well as for serodiagnostic purposes.