Overview of Modern Commercial Kits for Laboratory Diagnosis of African Swine Fever and Swine Influenza A Viruses.

Rapid and early detection of infectious diseases in pigs is important, especially for the implementation of control measures in suspected cases of African swine fever (ASF), as an effective and safe vaccine is not yet available in most of the affected countries. Additionally, analysis for swine influenza is of significance due to its high morbidity rate (up to 100%) despite a lower mortality rate compared to ASF. The wide distribution of swine influenza A virus (SwIAV) across various countries, the emergence of constantly new recombinant strains, and the danger of human infection underscore the need for rapid and accurate diagnosis. Several diagnostic approaches and commercial methods should be applied depending on the scenario, type of sample and the objective of the studies being implemented. At the early diagnosis of an outbreak, virus genome detection using a variety of PCR assays proves to be the most sensitive and specific technique. As the disease evolves, serology gains diagnostic value, as specific antibodies appear later in the course of the disease (after 7-10 days post-infection (DPI) for ASF and between 10-21 DPI for SwIAV). The ongoing development of commercial kits with enhanced sensitivity and specificity is evident. This review aims to analyse recent advances and current commercial kits utilised for the diagnosis of ASF and SwIAV.

Epidemiological Characterization of African Swine Fever Dynamics in Ukraine, 2012-2023.

African swine fever (ASF) is a viral disease, endemic to Africa, that causes high mortality when introduced into domestic pig populations. Since the emergence of p72-genotype II African swine fever virus (ASFV) in Georgia in 2007, an ASF epidemic has been spreading across Europe and many countries in Asia. The epidemic first reached Ukraine in 2012. To better understand the dynamics of spread of ASF in Ukraine, we analyzed spatial and temporal outbreak data reported in Ukraine between 2012 and mid-2023. The highest numbers of outbreaks were reported in 2017 (N = 163) and 2018 (N = 145), with overall peak numbers of ASF outbreaks reported in August (domestic pigs) and January (wild boars). While cases were reported from most of Ukraine, we found a directional spread from the eastern and northern borders towards the western and southern regions of Ukraine. Many of the early outbreaks (before 2016) were adjacent to the border, which is again true for more recent outbreaks in wild boar, but not for recent outbreaks in domestic pigs. Outbreaks prior to 2016 also occurred predominantly in areas with a below average domestic pig density. This new analysis suggests that wild boars may have played an important role in the introduction and early spread of ASF in Ukraine. However, in later years, the dynamic suggests human activity as the predominant driver of spread and a separation of ASF epizootics between domestic pigs and in wild boars. The decline in outbreaks since 2019 suggests that the implemented mitigation strategies are effective, even though long-term control or eradication remain challenging and will require continued intensive surveillance of ASF outbreak patterns.

Genome Sequence of Erysipelothrix sp. Strain Poltava, Isolated from Acute Septic Erysipelas of Swine in Ukraine.

The complete genome of Erysipelothrix sp. strain Poltava, isolated from fatal acute septic erysipelas of swine in Ukraine, was assembled using Nanopore sequences. One circular chromosome of 1,794,858 bp (N50, 1,794,858 bp) encodes 16 putative antibiotic resistance genes and secreted virulence factors, highlighting the risk of cross-species livestock and human infection.

Genetic Diversity of Porcine Circovirus 2 in Wild Boar and Domestic Pigs in Ukraine.

Porcine circovirus type 2 (PCV2) is responsible for a number of porcine circovirus-associated diseases (PCVAD) that can severely impact domestic pig herds. For a non-enveloped virus with a small genome (1.7 kb ssDNA), PCV2 is remarkably diverse, with eight genotypes (a-h). New genotypes of PCV2 can spread through the migration of wild boar, which are thought to infect domestic pigs and spread further through the domestic pig trade. Despite a large swine population, the diversity of PCV2 genotypes in Ukraine has been under-sampled, with few PCV2 genome sequences reported in the past decade. To gain a deeper understanding of PCV2 genotype diversity in Ukraine, samples of blood serum were collected from wild boars (n = 107) that were hunted in Ukraine during the November-December 2012 hunting season. We found 34/107 (31.8%) prevalence of PCV2 by diagnostic PCR. For domestic pigs, liver samples (n = 16) were collected from a commercial market near Kharkiv in 2019, of which 6 out of 16 (37%) samples were positive for PCV2. We sequenced the genotyping locus ORF2, a gene encoding the PCV2 viral capsid (Cap), for 11 wild boar and six domestic pig samples in Ukraine using an Oxford Nanopore MinION device. Of 17 samples with resolved genotypes, the PCV2 genotype b was the most common in wild boar samples (10 out of 11, 91%), while the domestic pigs were infected with genotypes b and d. We also detected genotype b/d and b/a co-infections in wild boars and domestic pigs, respectively, and for the first time in Ukraine we detected genotype f in a wild boar from Poltava. Building a maximum-likelihood phylogeny, we identified a sublineage of PCV2 genotype b infections in both wild and domestic swine, suggesting a possible epizootic cluster and an ecological interaction between wild boar and domestic pig populations in northeastern Ukraine.

Seroprevalence of Enzootic Teschen Disease in the Wild Boar Population in Ukraine.

Teschen disease is an acute fatal enterovirus encephalomyelitis of pigs, characterized by a range of central nervous system disorders. The cause of porcine enterovirus encephalomyelitis is the picornavirus porcine teschovirus-1 (PTV-1). There are at least 12 disctinct serotypes of PTVs, where PTV-2 to PTV-12 serogroups are associated with other forms of disease (Talfan disease or poliomyelitis suum) or benign enzootic paresis. Combined, PTVs have been found to have a high seroprevalence, up to 65%, in healthy pig populations in Europe. PTVs have also been detected in wild boar, including the divergent PTV-13 serogroup; wild suids may represent a sylvatic reservoir capable of carrying the virus long distances. In Ukraine, Teschen disease is widespread and causes lethal disease in domestic pigs. To understand temporal and geographical distribution of Teschen disease virus (PTV-1) in wild boar in Ukraine (2001-2013), we analyzed seroprevalence of 6840 blood serum samples from hunted suids using a virus microneutralization assay. A total of 1364 samples (19.9%) were seropositive, with average antibody titer ratios 5.89 ± 0.03 log2 (range 5-12 log2). Teschen seroprevalence was temporally and geographically concentrated in the northern and western regions of Ukraine, corresponding to forested regions (polissya) and overlapping with wild boar populations and habitats, suggesting endemicity in wild boar. The virus sporadically emerged in central, southern, and eastern forested regions, suggesting long-distance movement of infected wild suids. Thus, wild boar should be monitored for potential transboundary spread in forested and mountain regions and spillover of PTVs to domestic swine populations.