Olech Monika, Kuźmak Jacek
Department of Biochemistry, National Veterinary Research Institute, 24-100 Pulawy, Poland.
Pathogens. 2020 Nov 26;9(12):992. doi: 10.3390/pathogens9120992.
Small ruminant lentiviruses (SRLVs) are widespread in sheep and goats in Poland, and several subtypes were identified and molecularly characterized up to date. This is the first study that characterizes the molecular properties of A5 strains of SRLV detected in naturally infected, but clinically healthy, Carpathian goats. Segments from three genomic regions (gag, env, and LTR) were analyzed. Genetic distance, pairwise comparison, and phylogenetic analysis revealed that Polish SRLV A5 sequences are closely related to the Swiss and German A5 sequences suggesting a common origin. The epidemiological linkage was identified particularly between the small ruminants of Germany and Poland. Amino acid sequences of immunodominant regions in CA protein were well-conserved within analyzed strains; however, they showed some remarkable changes like substitution (D) to (E), at position 90 in Major Homology Region (MHR) and (T) to (S), at position 141 in epitope 3. In contrast, aa sequences of surface glycoprotein exhibited the highest variability confirming type-specific variation in SU5 epitope. Two deletions in the U3 region of A5 strains were noted: One (8 nt) located near the 5' end of the U3 region and the other (29 nt) located in the central region of U3. Additionally, all A5 strains had specific deletion (10 nt) in the R region. Furthermore, we did not find a correlation between copies of the CAAAT motif and clinical manifestation in infected animals. These data showed some remarkable features in the viral genome of A5 strains, which may be related to the attenuated phenotype in vivo, characterized by the lack of any clinical signs in infected goats. Certainly, more studies are required to support the hypothesis that these A5 viruses are of low pathogenicity for goats. We want to focus our future studies on the analysis of the whole genomes of these isolates and their biological properties, as well as on clinicopathological studies of goats infected by A5 SRLV, aiming to clarify the pathogenic potential of these viruses.
小反刍兽慢病毒（SRLV）在波兰的绵羊和山羊中广泛存在，截至目前已鉴定出几种亚型并对其进行了分子特征分析。这是第一项对在自然感染但临床健康的喀尔巴阡山羊中检测到的SRLV A5毒株的分子特性进行表征的研究。分析了三个基因组区域（gag、env和LTR）的片段。遗传距离、成对比较和系统发育分析表明，波兰SRLV A5序列与瑞士和德国的A5序列密切相关，表明它们有共同的起源。特别是在德国和波兰的小反刍动物之间确定了流行病学联系。在分析的毒株中，CA蛋白免疫显性区域的氨基酸序列保守性良好；然而，它们显示出一些显著变化，如主要同源区域（MHR）第90位的（D）被（E）取代，以及表位3中第141位的（T）被（S）取代。相比之下，表面糖蛋白的氨基酸序列表现出最高的变异性，证实了SU5表位的型特异性变异。注意到A5毒株的U3区域有两个缺失：一个（8个核苷酸）位于U3区域5'端附近，另一个（29个核苷酸）位于U3区域的中心区域。此外，所有A5毒株在R区域都有特定的缺失（10个核苷酸）。此外，我们没有发现CAAAT基序的拷贝数与感染动物的临床表现之间存在相关性。这些数据显示了A5毒株病毒基因组中的一些显著特征，这可能与体内减毒表型有关，其特征是感染山羊没有任何临床症状。当然，需要更多的研究来支持这些A5病毒对山羊致病性低的假设。我们希望将未来的研究重点放在这些分离株的全基因组分析及其生物学特性上，以及对感染A5 SRLV的山羊的临床病理学研究上，旨在阐明这些病毒的致病潜力。
