Fatal pulmonary parafilaroidiasis in a free-ranging subantarctic fur seal (Arctocephalus tropicalis) coinfected with two gammaherpesviruses and Sarcocystis sp.

Abstract A juvenile subantarctic fur seal (Arctocephalus tropicalis) found dead in Santa Catarina state, southern Brazil, presented with disseminated verminous pneumonia due to Parafilaroides sp. A concomitant infection with two different gammaherpesviruses was identified by PCR in different tissues; one of them possibly a novel species (tentatively named Otariid herpesvirus 7). Sarcocystis sp. DNA was identified molecularly in skeletal muscle samples with intrasarcoplasmic bradyzoites and no apparent tissue response. All analyzed samples (mandibular, laryngeal, tracheal, and mesenteric lymph nodes, and lung) were PCR-negative for Brucella spp. The most likely cause of death was severe pulmonary parafilaroidiasis. The pathogenic role of the gammaherpesviruses in several of the tissues was not evident. This study describes the pathogenicity of Parafilaroides sp. in a subantarctic fur seal, widens the host range of herpesvirus in pinnipeds, and reports the first molecular identification of Sarcocystis sp. in this species.

摘要：在巴西南部圣卡塔琳娜州发现一具死亡的幼年亚南极海狗（Arctocephalus tropicalis），尸检可见由副丝虫属（Parafilaroides sp.）感染引发的播散性丝状虫性肺炎。通过PCR技术在其不同组织中检出两种不同的γ疱疹病毒（gammaherpesvirus）合并感染，其中一种可能为新种，暂定名为海狮疱疹病毒7型（Otariid herpesvirus 7）。通过分子生物学手段在其骨骼肌样本中检出肉孢子虫属（Sarcocystis sp.）DNA，样本可见肌浆内缓殖子，但未观察到明显组织炎症反应。所有受检样本（下颌淋巴结、喉淋巴结、气管淋巴结、肠系膜淋巴结及肺组织）的布鲁氏菌属（Brucella spp.）PCR检测均呈阴性。该个体最可能的致死原因为重度肺副丝虫病。γ疱疹病毒在多种受检组织中的致病作用尚不明确。本研究阐明了副丝虫属（Parafilaroides sp.）在亚南极海狗体内的致病性，拓宽了疱疹病毒在鳍足类动物中的宿主范围，并首次报道了该物种中肉孢子虫属（Sarcocystis sp.）的分子鉴定结果。