Molecular detection of <i>Chlamydia psittaci</i> in birds: a systematic review

Molecular methods are currently the most sensitive for detecting Chlamydia psittaci in birds. Most laboratories have developed their own molecular assays or adapted published protocols, often making slight modifications to fit their specific study purposes. The sensitivity and specificity of a molecular test depend on the target gene, primer sequences, types of molecular test, DNA extraction method, and sampling methods. We reviewed 120 articles published between 2000 and 2020 to compile information on the molecular detection of C. psittaci in birds. Of the ten genomic targets currently available to detect C. psittaci in birds, the ompA gene was the most widely used. In published surveillance studies, of the fourteen molecular test types, conventional PCR and quantitative PCR were applied the most. A testing strategy using a hierarchical approach that includes molecular tests of genus- and species-specific targets is recommended to detect other avian chlamydial species besides the well-recognized C. psittaci. Samples should be sourced from both the respiratory and gastrointestinal tracts whenever possible for better accuracy. High-quality DNA can be obtained when the sample is preserved in optimal medium and temperature, and an optimized DNA extraction protocol is applied. Standardization and validation of molecular Chlamydia tests are needed to enhance the comparability and reliability of assays to detect C. psittaci and other chlamydiae species in birds. RESEARCH HIGHLIGHTS Hierarchical molecular testing is recommended for the detection of avian C. psittaci. Key molecular tests for surveillance were conventional PCR and quantitative PCR. The most used genomic target to detect C. psittaci in birds was the ompA gene. Hierarchical molecular testing is recommended for the detection of avian C. psittaci. Key molecular tests for surveillance were conventional PCR and quantitative PCR. The most used genomic target to detect C. psittaci in birds was the ompA gene.目前，分子生物学方法是检测鸟类鹦鹉热衣原体（Chlamydia psittaci）的最敏感手段。多数实验室已自主开发分子检测方法，或对已发表的实验方案进行适配性改造，通常会做出细微调整以契合自身特定研究需求。分子检测的灵敏度与特异性取决于靶基因、引物序列、分子检测类型、DNA提取方法以及采样方式。 本研究回顾了2000年至2020年间发表的120篇文献，汇编了鸟类鹦鹉热衣原体分子检测的相关信息。当前可用于检测鸟类鹦鹉热衣原体的10个基因组靶标中，ompA基因（ompA gene）的应用最为广泛。在已发表的监测类研究中，14种分子检测类型里，常规聚合酶链反应（PCR）与定量PCR的应用频次最高。 推荐采用包含属特异性与种特异性靶标的分层分子检测策略，以实现除公认鹦鹉热衣原体之外的其他禽衣原体物种的检测。为提升检测准确性，样本应尽可能同时采集自呼吸道与胃肠道组织。当样本保存于最优培养基与温度条件下，并采用优化的DNA提取方案时，可获得高质量的DNA。亟需对衣原体分子检测方法进行标准化与验证，以提升检测鸟类鹦鹉热衣原体及其他衣原体物种的实验的可比性与可靠性。 研究亮点 推荐采用分层分子检测策略用于禽源鹦鹉热衣原体的检测。 用于监测的关键分子检测手段为常规聚合酶链反应（PCR）与定量PCR。 鸟类鹦鹉热衣原体检测中应用最广泛的基因组靶标为ompA基因（ompA gene）。 推荐采用分层分子检测策略用于禽源鹦鹉热衣原体的检测。 用于监测的关键分子检测手段为常规聚合酶链反应（PCR）与定量PCR。 鸟类鹦鹉热衣原体检测中应用最广泛的基因组靶标为ompA基因（ompA gene）。