Cavicchio L, Tassoni L, Pastori A, Carrino M, Gagliazzo L, Mion M, Ustulin Martina, Vio D, Mantovani C, Ceglie L, Fusaro A, Beato M S
Diagnostic Virology Laboratory, Istituto Zooprofilattico Sperimentale delle Venezie (IZSVe), Padova, Italy.
Department of Comparative Biomedical Sciences, Istituto Zooprofilattico Sperimentale delle Venezie (IZSVe), Padova, Italy.
Front Microbiol. 2025 Jul 21;16:1607204. doi: 10.3389/fmicb.2025.1607204. eCollection 2025.
Swine Influenza is a respiratory disease endemic in pigs with implications for animal and public health. Pigs, as mixing vessels for human, avian, and swine influenza strains, contribute to viral reassortment and emergence of new strains. Influenza viruses can circulate and spread unnoticed between pig farms for extended periods, heightening the risk of reassortment events. This study aimed to monitor swine Influenza virus (swIAV) genetic diversity in Northern Italy and understand its evolution in the study area.
Passive surveillance, conducted from 2013 to 2022, involved 253 farms located in three regions, collecting over 3,000 samples that were tested for swIAV. Eighty-five samples underwent full genome sequencing, and phylogenetic analyses were conducted for each segment. In addition, cross-reactivity of viral strains was assessed using hemagglutination inhibition (HI) tests with hyperimmune swine sera.
Of the tested farms, 37.9% were positive for swIAV on at least one sampling event. Twelve distinct genotypes were identified, including two novel genotypes in Italy, both detected in 2022. Phylogenetic analyses revealed the presence of strictly correlated viruses in farms sharing the same owner or geographical proximity and highlighted multiple introductions and reassortment events in some farms. Cross HI tests demonstrated minimal antigenic cross-reactivity between circulating swIAV strains.
The study reveals a high genetic diversity in swIAV circulating in Northern Italy as a consequence of multiple virus introductions as well as new reassortment events with the identification of two new genotypes. The findings highlight the importance of sustained surveillance and genetic monitoring to track viral evolution and reassortment, which are pivotal for early detection of strains with pandemic potential.
猪流感是猪群中流行的一种呼吸道疾病，对动物和公共卫生都有影响。猪作为人流感、禽流感和猪流感病毒株的混合宿主，会导致病毒重配并产生新的毒株。流感病毒可在猪场之间长时间悄然传播和扩散，增加了重配事件的风险。本研究旨在监测意大利北部猪流感病毒（swIAV）的遗传多样性，并了解其在研究区域内的进化情况。
2013年至2022年进行的被动监测涉及位于三个地区的253个猪场，收集了3000多个样本进行swIAV检测。对85个样本进行了全基因组测序，并对每个片段进行了系统发育分析。此外，使用超免疫猪血清通过血凝抑制（HI）试验评估病毒株的交叉反应性。
在检测的猪场中，37.9%在至少一次采样事件中swIAV呈阳性。鉴定出12种不同的基因型，包括2022年在意大利检测到的两种新基因型。系统发育分析显示，在拥有相同所有者或地理位置相近的猪场中存在密切相关的病毒，并突出了一些猪场中的多次引入和重配事件。交叉HI试验表明，流行的swIAV毒株之间的抗原交叉反应性极小。
该研究揭示了由于多次病毒引入以及新的重配事件，导致意大利北部流行的swIAV具有高度的遗传多样性，并鉴定出两种新基因型。研究结果强调了持续监测和遗传监测对于追踪病毒进化和重配的重要性，这对于早期发现具有大流行潜力的毒株至关重要。
