Chronic Wasting Disease in Bank Voles: Characterisation of the Shortest Incubation Time Model for Prion Diseases

In order to assess the susceptibility of bank voles to chronic wasting disease (CWD), we inoculated voles carrying isoleucine or methionine at codon 109 (Bv109I and Bv109M, respectively) with CWD isolates from elk, mule deer and white-tailed deer. Efficient transmission rate (100%) was observed with mean survival times ranging from 156 to 281 days post inoculation. Subsequent passages in Bv109I allowed us to isolate from all CWD sources the same vole-adapted CWD strain (Bv109ICWD), typified by unprecedented short incubation times of 25–28 days and survival times of ~35 days. Neuropathological and molecular characterisation of Bv109ICWD showed that the classical features of mammalian prion diseases were all recapitulated in less than one month after intracerebral inoculation. Bv109ICWD was characterised by a mild and discrete distribution of spongiosis and relatively low levels of protease-resistant PrPSc (PrPres) in the same brain regions. Despite the low PrPres levels and the short time lapse available for its accumulation, end-point titration revealed that brains from terminally-ill voles contained up to 108,4 i.c. ID50 infectious units per gram. Bv109ICWD was efficiently replicated by protein misfolding cyclic amplification (PMCA) and the infectivity faithfully generated in vitro, as demonstrated by the preservation of the peculiar Bv109ICWD strain features on re-isolation in Bv109I. Overall, we provide evidence that the same CWD strain was isolated in Bv109I from the three-cervid species. Bv109ICWD showed unique characteristics of “virulence”, low PrPres accumulation and high infectivity, thus providing exceptional opportunities to improve basic knowledge of the relationship between PrPSc, neurodegeneration and infectivity

Animal models for COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the aetiological agent of coronavirus disease 2019 (COVID-19), an emerging respiratory infection caused by the introduction of a novel coronavirus into humans late in 2019 (first detected in Hubei province, China). As of 18 September 2020, SARS-CoV-2 has spread to 215 countries, has infected more than 30 million people and has caused more than 950,000 deaths. As humans do not have pre-existing immunity to SARS-CoV-2, there is an urgent need to develop therapeutic agents and vaccines to mitigate the current pandemic and to prevent the re-emergence of COVID-19. In February 2020, the World Health Organization (WHO) assembled an international panel to develop animal models for COVID-19 to accelerate the testing of vaccines and therapeutic agents. Here we summarize the findings to date and provides relevant information for preclinical testing of vaccine candidates and therapeutic agents for COVID-19

Detection and partial sequencing of Schmallenberg virus in cattle and sheep in Turkey.

To investigate the Schmallenberg virus (SBV) in Turkey, 116 aborted fetuses from sheep (60), goats (12), and cattle (44) collected from different regions of Turkey were analyzed by real-time PCR. SBV RNA was detected in aborted fetuses of sheep and cattle from the Marmara region, which borders the European Union. In contrast, samples were found to be negative for Akabane virus by real-time PCR. The partial sequencing of the S gene of SBV confirmed the first detection of SBV in Turkey

Bovine spongiform encephalopathy in Sweden: an H-type variant

Bovine spongiform encephalopathy (BSE) had never been detected in Sweden until 2006, when the active surveillance identified a case in a 12-year-old cow. The case was an unusual form, because several molecular features of the protease-resistant prion protein (PrPres) were different from classical BSE. The differences included higher susceptibility for proteinase K, higher molecular weight of the PrPres bands, affinity to the N-terminus¿specific antibodies 12B2 and P4, and peculiar banding pattern with antibody SAF84 showing an additional band at the 14 kDa position. The molecular characteristics were in accordance to previous descriptions of H-type BSE. This report shows that a range of Western blot techniques and antibodies can be applied to confirm H-type BSE and further describes that the ratio of the amounts of PrPres#1 and PrPres#2, after deglycosylation, depends on the antibody used during processing. Immunohistochemistry on sections of medulla at the level of the obex applying antibodies with epitopes covering a broad range of the PrP sequence showed accumulation of disease-specific PrP (PrPd) in the gray matter. Fine punctate deposition in the neuropil was the most predominant type and was more severe in BSE target nuclei. The types of PrPd deposition are described in comparison with classical BSE. PrP-gene sequencing showed 6 copy octarepeat alleles and no abnormalities. It is postulated that the disease had a spontaneous origin, rather than having had been acquired in the BSE epidemic

Evaluation of two commercial, rapid, ELISA kits testing or scrapie in retro-pharyngeal lymph nodes in sheep

AIMS: To estimate the number of cases of scrapie that would occur in sheep of different prion protein (PrP) genotypes if scrapie was to become established in New Zealand, and to compare the performance of two commercially available, rapid ELISA kits using ovine retro-pharyngeal lymph nodes (RLN) from non-infected and infected sheep of different PrP genotypes. METHODS: Using published data on the distribution of PrP genotypes within the New Zealand sheep flock and the prevalence of cases of scrapie in these genotypes in the United Kingdom, the annual expected number of cases of scrapie per genotype was estimated, should scrapie become established in New Zealand, assuming a total population of 28 million sheep. A non-infected panel of RLN was collected from 737 sheep from New Zealand that had been culled, found in extremis or died. Brain stem samples were also collected from 131 of these sheep. A second panel of infected samples comprised 218 and 117 RLN from confirmed scrapie cases that had originated in Europe and the United States of America, respectively. All samples were screened using two commercial, rapid, transmissible spongiform encephalopathy ELISA kits: Bio-Rad TeSeE ELISA (ELISA-BR), and IDEXX HerdChek BSE-Scrapie AG Test (ELISA-ID). RESULTS: If scrapie became established in New Zealand, an estimated 596 cases would occur per year; of these 234 (39%) and 271 (46%) would be in sheep carrying ARQ/ARQ and ARQ/VRQ PrP genotypes, respectively. For the non-infected samples from New Zealand the diagnostic specificity of both ELISA kits was 100%. When considering all infected samples, the diagnostic sensitivity was 70.4 (95% CI=65.3-75.3)% for ELISA-BR and 91.6 (95% CI=88.2-94.4)% for ELISA-ID. For the ARQ/ARQ genotype (n=195), sensitivity was 66.2% for ELISA-BR and 90.8% for ELISA-ID, and for the ARQ/VRQ genotype (n=107), sensitivity was 81.3% for ELISA-BR and 98.1% for ELISA-ID. CONCLUSIONS: In this study, the ELISA-ID kit demonstrated a higher diagnostic sensitivity for detecting scrapie in samples of RLN from sheep carrying scrapie-susceptible PrP genotypes than the ELISA-BR kit at comparable diagnostic specificity

Modeling of output parameters of the silicon solar cells with i-type conductivity base crystals

Проведено експериментальне дослідження та моделювання із використанням програми PC1D ви- хідних параметрів лабораторних зразків фотоелектричних перетворювачів на основі монокристалічного кремнію і-типу електропровідності. Встановлено, що використання базових кристалів і-типу еле- ктропровідності в умовах опромінення АМ0 дозволяє отримувати рекордно високі значення густини фотоструму, котрі сягають 48,6 мА/см2. Проте їх коефіцієнт корисної дії не перевищує 11,6 %. Для розробки фізично обґрунтованого підходу до оптимізації конструктивно-технологічних рішень проана- лізовано електронну модель кремнієвого фотоелектричного перетворювача з p+-i-n+ структурою. В ході апробації моделі було одержано серію діаграм розподілу значень коефіцієнта корисної дії досліджуваних фотоелектричних перетворювачів з p+-i-n+ структурою залежно від значень послідовного і шунтувального опорів при густині діодного струму насичення 10 – 7 А/см2, 10 – 8 А/см2 та 10 – 9 А/см2. Наявність таких діаграм при проведенні розробки високоефективних фотоперетворювачів зазначеного типу дозволить не тільки суттєво зменшити витрати на пошукові дослідження, але й забезпечить досягнення необхідного у кожному конкретному випадку оптимального співвідношення між витратами на покращення діодної структури та підвищеним рівнем коефіцієнта корисної дії таких приладів.Проведено экспериментальное исследование и моделирование с использованием программы PC1D выходных параметров лабораторных образцов фотоэлектрических преобразователей на основе монокристаллического кремния і-типа электропроводности. Установлено, что использование базовых кристаллов і-типа электропроводности в условиях облучения АМ0 позволяет получить рекордно высокие значения плотности фототока, достигающие 48,6 мА/см2. Однако их коэффициент полезного действия не превышает 11,6 %. Для разработки физически обоснованного подхода к оптимизации конструктивно-технологических решений проанализирована электронная модель кремниевого фотоэлектрического преобразователя з p+-i-n+ структурою. В ходе апробации модели была получена серия диаграмм распределения значений коэффициента полезного действия исследуемых фотоэлектрических преобразователей с p+-i-n+ структурой в зависимости от значений последовательного и шунтирующего сопротивлений при плотности диодного тока насыщения 10– 7 А/см2, 10– 8 А/см2 и 10– 9 А/см2. Наличие таких диаграмм при проведении разработки высокоэффективных фотопреобразователей указанного типа позволит не только существенно уменьшить затраты на поисковые исследования, но и обеспечит достижение необходимого в каждом конкретном случае оптимального соотношения между затратами на улучшение диодной структуры та повышенным уровнем коэффициента полезного действия таких приборов.It was carried out the experimental investigation and modeling of the solar cells based on single crystal silicon with i-type conductivity laboratory samples output parameters using PC1D program. It has been found that use of i-type conductivity base crystals under AM0 irradiation allows to reach the record high photocurrent density values up to 48.6 mA/cm2. However, their efficiency does not exceed 11.6 %. To develop the physically based approach to optimize construction-technological solutions it has been analyzed the electronic model of silicon solar cells with p+-i-n+ structure. During the testing of the model we have obtained a series of diagrams with distribution of the investigated solar cells with p+-i-n+ structure efficiency values, depending on the values of series and shunt resistances at the diode saturation current density of 10 – 7 A/cm2 and 10 – 8 A/cm2 10 – 9 A/cm2. Availability of these diagrams during the development of such type highly effective solar cells will not only significantly reduce the cost of exploratory research but also will produce the required in each particular case an optimum ratio between the costs of diode structure improving and increased level of such devices efficiency