犬傳染性呼吸道疾病之病毒核酸診斷與臨床病例分析

Abstract

犬傳染性呼吸道疾病 (canine infectious respiratory disease) 是狗的呼吸道感染症之統稱，目前已知可引起CIRD的病原涵蓋了病毒與細菌兩大類，在病毒的部份主要有犬瘟熱病毒 (canine distemper virus, CDV)、犬第二型副黏液病毒 (canine parainfluenza virus type 2, CPIV-2)、犬疱疹病毒 (canine herpesvirus, CHV)、犬第一型與第二型腺病毒 (canine adenovirus type 1 and type 2；CAV-1 and CAV-2)，以及 (canine respiratory coronavirus；CRCoV) 等。以RT-nPCR / n-PCR為基礎的特異性核酸診斷技術，針對臨床54個家犬病例的進行偵測，檢出率依序為：CDV 41 %、CAV-2 28 %、CPIV-2 13 %、CRCoV 8 % 以及CHV 4 %。偵測到的混合感染型式有CDV和CPIV-2 (9 %)、CDV和CAV-2 (7 %)、CAV-2和CPIV-2 (4 %)，以及CDV和CHV (2 %)、CAV-2、CHV與CRCoV (2 %)、CDV、CAV-2與CRCoV (2 %)。多重檢體偵測的結果以鼻腔、口腔、眼結膜拭子的平均檢出率較高，血液則最差。將核酸診斷所增幅出的陽性產物片段進行定序分析，本土株之間的相似度為98.7 – 100 %，與GenBank中已發表的國外毒株基因序列比對後的相似度為95 – 100 %，在CRCoV、CPIV-2、CHV的數個核苷酸變異可供區別本土株與國外毒株。在病毒感染與臨床症狀的統計分析，證實任一種呼吸道病毒感染會使上呼吸道症狀變得更嚴重 (P < 0.01)，尤其是單純CAV感染 (P < 0.05)、CDV單純與混合感染 (P < 0.05)，以及CAV單純和其他病毒混合感染 (P < 0.01)；任一種呼吸道病毒感染會使患犬出現化膿性鼻分泌物的情形增加 (P < 0.01)，尤其是牽涉到CDV與CAV的感染會使得上呼吸道二次性細菌感染的機率提高 (P < 0.05)。在呼吸道病例中，CAV和CPIV混合感染以及CDV所有的混合感染型式 (不包括單純感染) 會使得患犬嘔吐的情形增加 (P < 0.05)。在呼吸道病例中，無論是CDV的單純或混合感染，皆會使得患犬下痢症狀出現的情形增加 (P < 0.01)。

Canine infectious respiratory disease (CIRD) is a general call of respiratory infections in dogs. Several studies of natural outbreaks of the disease have shown that the etiology is complex, with a variety of viruses and bacteria involved. The viruses that have been most frequently reported to be present are canine distemper virus (CDV), canine adenovirus type 1 and type 2 (CAV-1 and CAV-2), canine herpesvirus (CHV), canine parainfluenza virus type 2 (CPIV-2), and canine respiratory coronavirus (CRCoV). We detected these viruses from clinical samples of 54 cases with specific nucleic acid diagnostic assays based on RT-nPCR / n-PCR, and obtained the detection rates as follows: CDV: 41 %; CAV-2: 28 %; CPIV-2: 13 %; CRCoV: 8 %; CHV: 4 %. A population of dogs (26%) had evidence of infections with several viruses at the same time. The coinfection patterns are: CDV with CPIV-2 (9 %), CDV with CAV-2 (7 %), CAV-2 with CPIV-2 (4 %), and CDV with CHV (2 %). The infectious patterns involved with three viruses including: CAV-2, CHV and CRCoV (2 %); CDV, CAV-2 and CRCoV (2 %). Generally speaking, detection rates of nasal swab, oral swab and conjunctival swab have a elevation compared with whole blood. The gene sequence results of the RT-nPCR and n-PCR products of representative positive samples showed 98.7 – 100% nucleotide identity with corresponding viral gene and 95 – 100% with foreign strains. The nucleotides variation in CRCoV, CPIV-2, and CHV can be differentiated local strains form foreign strains. According to the statistical analysis results, any infectious pattern of these virus showed a significant variability with the severity of upper respiratory symptoms (P < 0.01), and higher variability in secondary bacterial infections (P < 0.01). In some particular viral infections showed a significant variability with the clinical sign of vomiting and diarrhea (P < 0.05)