Epidemiological investigation and genetic evolutionary analysis of PRRSV-1 on a pig farm in China

Porcine reproductive and respiratory syndrome virus (PRRSV) has brought serious economic losses to pig industry. PRRSV-1 have existed in China for more than 25 years. The prevalence and features of PRRSV-1 on Chinese farms are unclear. We continuously monitored PRRSV in a pig farm with strict biosafety measures in Henan Province, China, in 2020. The results showed that multiple types of PRRSV coexisted on this single pig farm. PRRSV-1 was one of the main circulating strains on the farm and was responsible for infections throughout nearly the entire epidemic cycle. Phylogenetic analysis showed that PRRSV-1 isolates from this pig farm formed an independent branch, with all isolates belonging to BJEU06-1-like PRRSV. The analysis of selection pressure on ORF5 on this branch identified 5 amino acids as positive selection sites, indicating that PRRSV-1 had undergone adaptive evolution on this farm. According to the analysis of ORF5 of PRRSV-1 on this farm, the evolutionary rate of the BJEU06-1-like branch was estimated to be 1.01 × 10^-2 substitutions/site/year. To further understand the genome-wide characteristics of PRRSV-1 on this pig farm, two full-length PRRSV-1 genomes representative of pig farms were obtained. The results of amino acid alignment revealed that although one NSP2 deletion was consistent with BJEU06-1, different new features were found in ORF3 and ORF4. According to the above results, PRRSV-1 has undergone considerable evolution in China. This study is the first to report the prevalence and characteristics of PRRSV-1 on a large farm in mainland China, which will provide a reference for the identification and further prevention and control of PRRSV-1.

Molecular characterization and pathological identification of a novel strain of delta papillomavirus-4 (bovine papillomavirus-2) in Egypt

Background and Aim:

Bovine papillomaviruses (BPV) are a heterogeneous group of oncoviruses, distributed globally, which produce major economic losses. In the current study, we compared the results of different diagnostic approaches and compared the strains identified in this study with previously characterized strains at local and international levels.

Materials and Methods:

Samples of skin warts were collected from five bovines with generalized papillomatosis from two Egyptian provinces, Menya and Ismailia, in 2020. Electron microscopy, molecular characterization, histopathological, and immunohistochemical examination were performed.

Results:

BPV was detected using electron microscopy in the collected samples. Using molecular characterization, BPV-2 was successfully identified for 1^st time in Egypt. The strain has 99.6% identity with the BPV-2 reference strains obtained from GenBank. These results were supported by histopathology and immunohistochemistry examination. Partial nucleotide sequences of the L1 gene were submitted to GenBank with accession numbers MW289843 and MW289844.

Conclusion:

BPV-2 was reported for 1^st time in the current study. The strain was identified grossly, microscopically, and pathologically and confirmed using molecular approaches. All results were consistent. The sequence analysis revealed that this strain has high sequence similarity to the reference Deltapapillomavirus-4, BPV-2 strains from Brazil and China.

Encephalitis and Death in Wild Mammals at a Rehabilitation Center after Infection with Highly Pathogenic Avian Influenza A(H5N8) Virus, United Kingdom

We report a disease and mortality event involving swans, seals, and a fox at a wildlife rehabilitation center in the United Kingdom during late 2020. Five swans had onset of highly pathogenic avian influenza virus infection while in captivity. Subsequently, 5 seals and a fox died (or were euthanized) after onset of clinical disease. Avian-origin influenza A virus subtype H5N8 was retrospectively determined as the cause of disease. Infection in the seals manifested as seizures, and immunohistochemical and molecular testing on postmortem samples detected a neurologic distribution of viral products. The fox died overnight after sudden onset of inappetence, and postmortem tissues revealed neurologic and respiratory distribution of viral products. Live virus was isolated from the swans, seals, and the fox, and a single genetic change was detected as a potential adaptive mutation in the mammalian-derived viral sequences. No human influenza-like illness was reported in the weeks after the event.

The First Detection of Kudoa hexapunctata in Farmed Pacific Bluefin Tuna in South Korea, Thunnus orientalis (Temminck and Schlegel, 1844)

Simple Summary

In this study, we detected Kudoa hexapunctata in Pacific bluefin tuna (Thunnus orientalis) individuals that did not show any gross pathology lesions. Giemsa staining was used to identify clearer lesions than haematoxylin and eosin (H&E) staining that is used in general histological analysis. K. hexapunctata was separated through molecular biological methods, other than haematolocial and histological analysis. Individuals infected with K. hexapunctata showed relatively low haemoglobin (Hb) and haematocrit (Ht) values, and histological analysis revealed clear pseudocysts in the abdominal and dorsal muscles.

Abstract

The consumption of fish and shellfish worldwide is steadily increasing, and tuna is a particularly valuable fish species. However, infection caused by Kudoa spp. is causing problems in many fish including the Pacific bluefin tuna (Thunnus orientalis), and there is much controversy about the association of these infections with foodborne disease. In this study, using haematological and histological analyses of the blood and internal organs (liver, spleen, kidney, heart, stomach, intestine, gill, and muscle) of Pacific bluefin tuna cultured in South Korea, infection with Myxosporea was first identified, and molecular biological analysis was conducted. In this study, Kudoa hexapunctata was finally identified. The Pacific bluefin tunas analysed in this study did not show any gross pathology lesions, such as visible cysts and/or myoliquefaction, of infection with this species. The histological analytical results can provide guidelines for the identification of K. hexapunctata. In the case of K. hexapunctata-induced infection, unlike other countries, such as Japan, there have been no reports in South Korea, and this study is the first to detect K. hexapunctata infection in Pacific bluefin tuna cultured in South Korea. The correlation between K. hexapunctata and food poisoning is not yet clear, however, it is thought that continuous observation of its infection is necessary.

First Report of the Spiral Nematode Helicotylenchus microlobus Infecting Soybean in North Dakota

Spiral nematodes (Helicotylenchus spp.) are common plant-parasitic nematodes in fields of many crops. In June 2015, two soil samples were collected from a soybean field in Richland County, ND. Nematodes were extracted from soil using the sugar centrifugal flotation method (Jenkins, 1964). Plant-parasitic nematodes were identified to genus based on morphological features and counted. Both samples contained spiral nematodes from 1,500 to 3,300 per kilogram of soil. In June and August 2016, 10 soil samples were collected from the same field. Nematodes were extracted, and nine of the samples had spiral nematodes ranging from 125 to 3,065 per kilogram of soil. One soil sample with 1,500 spiral nematodes per kilogram was used to inoculate two soybean cultivars Sheyenne and Barnes each in four replicates. After 15 wk of growth at 22°C in a greenhouse room, the population of spiral nematodes was found to have increased greatly. The final density was 9,300 ± 1,701 spiral nematodes per kilogram of soil for Sheyenne and 9,451 ± 2,751 for Barnes. The reproductive factor in Sheyenne and Barnes was 6.2 and 6.3, respectively, indicating that this spiral nematode infects and reproduces well on these two soybean cultivars. Infected soybean roots had small brown lesions on the surface. Individual spiral nematodes were handpicked and examined morphologically and molecularly for species identification. Morphological measurements of adult females (n = 15) included body length (mean = 708.5 μm, range = 600.0-812.0 μm), stylet (27.6, 26.0-29.0), body width (28.3, 25.0-33.0), lip region end to posterior end of pharyngeal glands (142.5, 130.0-152.0), anal body width (15.8, 14.0-17.5), tail length (20.3, 15.0-25.0), tail annules (11.6, 10.0-14.0), a (25.0, 21.4-27.1), b (5.0, 4.4-5.7), c (35.4, 30.2-41.7), c' (1.3, 1.0-1.6), and V (61.8%, 60.0-63.7). The spiral nematode was identified as Helicotylenchus microlobus according to morphological and morphometric characteristics (Subbotin et al., 2015). DNA was extracted from single nematodes (n = 8) using the Proteinase K method (Kumari and Subbotin, 2012). The internal transcribed spacer (ITS) region of rDNA was amplified with the primers rDNA2/rDNA1.58S (Cherry et al., 1997). The PCR products were then purified and sequenced. The consensus ITS rDNA sequence (accession no. KY271078, 822 bp) that was deposited into the GenBank shared 99% identity with two isolates of H. microlobus from California (KM506860.1 and KM506859.1) and one isolate of H. microlobus from Spain (KM506862.1) (Subbotin et al., 2015). It had only 91% sequence identity with seven isolates of H. pseudorobustus (KM506875.1, KM506880.1, KM506876.1, KM506874.1, KM506872.1, KM506879.1, and KM506878.1) from California, Switzerland, and New Zealand, a spiral nematode species very closely related to H. microlobus in morphology. The molecular tests confirmed the identity of this spiral nematode as H. microlobus. The H. microlobus nematode was reported as one of the most commonly observed spiral nematodes in soil samples in the state of Minnesota, and all 13 soybean cultivars tested except Hawkeye were rated as hosts (Taylor, 1960). To our knowledge, this is the first report of H. microlobus in North Dakota.