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The small hive beetle (SHB), Aethina tumida Murray, is a parasite of honey bee colonies and causes the fermentation of honey as well as colony collapse. Outbreaks have been confirmed in Africa, America, Europe as well as Asia, where an outbreak was reported in the Philippines and South Korea in 2014 and 2017, respectively. In South Korea, in September 2016, this honey bee parasite was first identified in apiaries in Miryang, Gyeongnam Province. However, the invasion pathway of SHB has not been identified, and honey bee pathogens harbored by SHB have not been well characterized. Therefore, phylogenetic analysis of SHB with the use of COI gene and detection of fourteen common honey bee pathogens were conducted in this study. The confirmation of the fourteen honey bee pathogens in SHB showed that this beetle carries black queen cell virus and deformed wing virus. Therefore, SHB could have a role in the spread of these viruses. The way of entry of the SHB to South Korea remains undetermined, but the phylogenetic analysis of the COI gene revealed that it was most similar to species found in the USA. There is an urgent need for national-level monitoring and quarantine measures for preventing the spread of SHB infestation in South Korea.

Understanding the molecular interactions between porcine reproductive and respiratory syndrome viruses (PRRSVs) and host cells is crucial for developing effective strategies against PRRSV. CD163, predominantly expressed in porcine macrophages and monocytes, is a key receptor for PRRSV infection. CD169, also known as Sialoadhesin, has emerged as a potential receptor facilitating PRRSV internalization. In this study, we investigated PRRSV susceptibility in relation to CD169 expression in CD163-expressing cells. Susceptibility to PRRSV infection was estimated by immunostaining the N protein using SR30A and quantifying ORF7 using RT-PCR. PRRSV strains adapted to MARC-145 did not infect CD163+/CD169-cells but successfully replicated in CD163+/CD169+ cells. Similarly, porcine alveolar macrophage-isolated PRRSV strains effectively infected and propagated in CD163+/CD169+ cells compared to CD163+/CD169-cells (100% vs. 82.9%). We confirmed that high CD169 expression in CD163-expressing cells increases susceptibility to PRRSVs compared to low or no CD169 expression. In conclusion, CD169 expression level influences viral entry efficiency into CD163-expressing cells, providing valuable insights for isolating wild PRRSVs and producing high-titer PRRS vaccine candidates. [ABSTRACT FROM AUTHOR]

Tick-borne diseases are a public health problem and a significant burden on the livestock industry. The seasonal abundance of ticks and tick-borne pathogens strongly correlates with the prevalence of these diseases. To investigate the seasonal variation in ticks and tick-borne pathogens, ticks were collected from Gangwon State, Korea, and the tick-borne pathogens Borrelia, Anaplasma, Babesia, and Theileria were examined. In total, 14,748 ticks were collected, comprising ticks from two genera and three species: Haemaphysalis longicornis, Haemaphysalis flava, and Ixodes nipponensis, with H. longicornis being the predominant species. Of 7445 ticks (455 pools) examined for pathogens, Theileria was detected in 61 pools, whereas Borrelia and Anaplasma were observed in 17 pools. H. longicornis nymphs and adults were collected beginning in April, with nymph numbers peaking in May and June and adult ticks peaking in June and July. In contrast, the larvae were collected in May and peaked in September. Tick-borne pathogens were detected in April, peaking in July and September. Borrelia, the causative agent of Lyme disease, exhibits a temporal association between its detection in ticks and its occurrence in humans. In conclusion, tick-borne diseases seem to be closely linked not only to changes in tick numbers throughout the seasons but also to the seasonal variations of the pathogens within them. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the diversity and prevalence of tick-borne protists in the Republic of Korea via DNA barcoding using 18S rRNA gene fragments and PCR. Between 2021 and 2022, questing ticks were collected using the flagging method, with a total of 13,375 ticks collected and pooled into 1003 samples. Of these, 50 tick pools were selected for DNA barcoding targeting the V4 and V9 regions of 18S rRNA using the MiSeq platform. A taxonomic analysis of the amplicon sequence variants identified three genera of protozoa, namely Hepatozoon canis, Theileria luwenshuni, and Gregarine sp. However, the number and abundance of protists detected were different depending on the primer sets, and T. gondii was not identified in DNA barcoding. Furthermore, conventional PCR confirmed the presence of H. canis, Toxoplasma gondii, T. luwenshuni, and Theileria sp. in the collected ticks. This study identified H. canis and T. gondii in Ixodes nipponensis for the first time. It demonstrated that the results of DNA barcoding using 18S rRNA gene fragments can vary depending on the primer sets and further optimization is required for library construction to identify tick-borne protists in ticks. Despite these limitations, the findings highlight the potential of DNA barcoding using 18S rRNA gene fragments for screening the diversity of tick-borne protists in ticks. [ABSTRACT FROM AUTHOR]

The honey bee is an important pollinator of wild plants and crops and provides various useful products for humans. Infestations by honey bee mites damage the honey bees' health, decrease their lifespan, and increase their viral susceptibility. In this study, surveys were conducted throughout South Korea in 2019 to investigate the status of honey bee mite infestation. Mite samples were collected for species identification, and estimation of infestation levels from 47 apiaries in 12 regions was conducted. Mite species were identified by morphological characteristics and genetic analysis using cytochrome c oxidase subunit I (COX1). The results showed that 93.6% of the apiaries were infested by honey bee mites, of which 85.1% and 76.6% of the apiaries were infested by Varroa spp. and Tropilaelaps spp., respectively. Furthermore, 68.0% were co-infested by both honey bee mites. Additionally, 82.5% of the apiaries with Varroa spp. showed infestation rate with >3 mites per 100 bees, the infestation level could result in winter losses of honey bee colonies. Species identification revealed that all mites from the apiaries in South Korea were Varroa destructor and Tropilaelaps mercedesae. Importantly, these two mite species were determined to be vectors of one to nine honey bee pathogens in real-time polymerase chain reaction detection. The most prevalent pathogen was the deformed wing virus, followed by the Israeli acute paralysis virus and chronic bee paralysis virus. The results of the surveys are important for estimating the economic losses caused by honey bee mites and establishing a possible strategy for controlling mites and mite-borne transmissible pathogens in South Korea. [ABSTRACT FROM AUTHOR]