Detection of Feline Coronavirus in Feline Effusions by Immunofluorescence Staining and Reverse Transcription Polymerase Chain Reaction.

Feline coronavirus (FCoV), the pathogen for feline infectious peritonitis, is a lethal infectious agent that can cause effusions in the pleural and abdominal cavities in domestic cats. To study the epidemiology of FCoV in Taiwan, 81 FIP-suspected sick cats with effusive specimens were recruited to test for FCoV infection using immunofluorescence staining and reverse transcription-polymerase chain reaction as detection methods, and viral RNAs were recovered from the specimens to conduct genotyping and phylogenetic analysis based on the spike (S) protein gene. The results revealed that a total of 47 (47/81, 58%) of the sick cats were positive for FCoV in the effusion samples, of which 39 were successfully sequenced and comprised of 21 type I strains, 9 type II strains, and 9 co-infections. The signalment analysis of these sick cats revealed that only the sex of cats showed a significant association (odds ratio = 2.74, 95% confidence interval = 1.06-7.07, p = 0.03) with the infection of FCoV, while age and breed showed no association. FCoV-positive cats demonstrated a significantly lower albumin to globulin ratio than negative individuals (p = 0.0004). The partial S gene-based phylogenetic analysis revealed that the type I strains demonstrated genetic diversity forming several clades, while the type II strains were more conserved. This study demonstrates the latest epidemiological status of FCoV infection in the northern part of Taiwan among sick cats and presents comparisons of Taiwan and other countries.

Tag-Free SARS-CoV-2 Receptor Binding Domain (RBD), but Not C-Terminal Tagged SARS-CoV-2 RBD, Induces a Rapid and Potent Neutralizing Antibody Response.

Recombinant proteins are essential in the development of subunit vaccines. In the design of many recombinant proteins, polyhistidine residues are added to the N- or C-termini of target sequences to facilitate purification. However, whether the addition of tag residues influences the immunogenicity of proteins remains unknown. In this study, the tag-free SARS-CoV-2 RBD and His-tag SARS-CoV-2 RBD proteins were investigated to determine whether there were any differences in their receptor binding affinity and immunogenicity. The results showed that the tag-free RBD protein had a higher affinity for binding with hACE2 receptors than His-tag RBD proteins (EC50: 1.78 µM vs. 7.51 µM). On day 21 after primary immunization with the proteins, the serum ELISA titers of immunized mice were measured and found to be 1:1418 for those immunized with tag-free RBD and only 1:2.4 for His-tag RBD. Two weeks after the booster dose, tag-free-RBD-immunized mice demonstrated a significantly higher neutralizing titer of 1:369 compared with 1:7.9 for His-tag-RBD-immunized mice. Furthermore, neutralizing antibodies induced by tag-free RBD persisted for up to 5 months and demonstrated greater cross-neutralization of the SARS-CoV-2 Delta variant. Evidence from Western blotting showed that the serum of His-tag-RBD-immunized mice recognized irrelevant His-tag proteins. Collectively, we conclude that the addition of a polyhistidine tag on a recombinant protein, when used as a COVID-19 vaccine antigen, may significantly impair protein immunogenicity against SARS-CoV-2. Antibody responses induced were clearly more rapid and robust for the tag-free SARS-CoV-2 RBD than the His-tag SARS-CoV-2 RBD. These findings provide important information for the design of antigens used in the development of COVID-19 subunit vaccines.

COVID-19 in a Child With Transposition of the Great Arteries S/P Fontan Palliation: A Case Report and Literature Review.

Background: Although adult patients with cardiovascular disease are at higher risk of adverse outcomes such as death or severe infection, limited data exist regarding pediatric patients with congenital heart disease. We would like to report our experience with COVID-19 in a pediatric patient with Fontan circulation. Furthermore, we present a review of patients with Fontan palliation and COVID-19 previously reported in the literature to summarize the clinical characteristics of this population. Case Presentation: A 9-year-old boy with dextro-transposition of the great arteries, ventricular septal defect, pulmonary stenosis, patent foramen ovale, and borderline left ventricle post bidirectional Glenn shunt and Fontan palliation presented with paroxysmal cough in the context of COVID-19. The coagulation profile was beyond the normal limits, and the patient began to receive anticoagulant aspirin. On the 5th day, the patient presented with fever, sore throat, and fatigue. The oxygen saturations dropped to 93%, and he received nasal catheter oxygen inhalation. On the 7th day, computed tomography of the chest revealed little emerging flaky exudation in the posterior basal segment of the left lower lobe. Nasal cannula was removed on the 12th day, and the coagulation profile returned to normal on the 16th day. After two consecutively negative SARS-CoV-2 viral RNA tests (on the 18th and 19th days, interval ≥ 24 h), he was discharged from the hospital on the 21st day. Literature review indicated that COVID-19 with Fontan palliation seemed to be more common in male adults. Disease presentation varied from mild upper respiratory tract infection to severe pneumonia. Complications were not uncommon in this population. The treatments varied depending on the specific factors. Fortunately, most patients reported a favorable prognosis. Conclusion: Although patients with COVID-19 and Fontan circulation might have the risk of adverse outcomes due to multiple mechanisms, most patients have a favorable prognosis.

COVID-19 in a Child With Transposition of the Great Arteries S/P Fontan Palliation: A Case Report and Literature Review

Background Although adult patients with cardiovascular disease are at higher risk of adverse outcomes such as death or severe infection, limited data exist regarding pediatric patients with congenital heart disease. We would like to report our experience with COVID-19 in a pediatric patient with Fontan circulation. Furthermore, we present a review of patients with Fontan palliation and COVID-19 previously reported in the literature to summarize the clinical characteristics of this population. Case Presentation A 9-year-old boy with dextro-transposition of the great arteries, ventricular septal defect, pulmonary stenosis, patent foramen ovale, and borderline left ventricle post bidirectional Glenn shunt and Fontan palliation presented with paroxysmal cough in the context of COVID-19. The coagulation profile was beyond the normal limits, and the patient began to receive anticoagulant aspirin. On the 5th day, the patient presented with fever, sore throat, and fatigue. The oxygen saturations dropped to 93%, and he received nasal catheter oxygen inhalation. On the 7th day, computed tomography of the chest revealed little emerging flaky exudation in the posterior basal segment of the left lower lobe. Nasal cannula was removed on the 12th day, and the coagulation profile returned to normal on the 16th day. After two consecutively negative SARS-CoV-2 viral RNA tests (on the 18th and 19th days, interval ≥ 24 h), he was discharged from the hospital on the 21st day. Literature review indicated that COVID-19 with Fontan palliation seemed to be more common in male adults. Disease presentation varied from mild upper respiratory tract infection to severe pneumonia. Complications were not uncommon in this population. The treatments varied depending on the specific factors. Fortunately, most patients reported a favorable prognosis. Conclusion Although patients with COVID-19 and Fontan circulation might have the risk of adverse outcomes due to multiple mechanisms, most patients have a favorable prognosis.

Robust induction of TRMs by combinatorial nanoshells confers cross-strain sterilizing immunity against lethal influenza viruses.

Antigen-specific lung-resident memory T cells (TRMs) constitute the first line of defense that mediates rapid protection against respiratory pathogens and inspires novel vaccine designs against infectious pandemic threats, yet effective means of inducing TRMs, particularly via non-viral vectors, remain challenging. Here, we demonstrate safe and potent induction of lung-resident TRMs using a biodegradable polymeric nanoshell that co-encapsulates antigenic peptides and TLR9 agonist CpG-oligodeoxynucleotide (CpG-ODN) in a virus-mimicking structure. Through subcutaneous priming and intranasal boosting, the combinatorial nanoshell vaccine elicits prominent lung-resident CD4+ and CD8+ T cells that surprisingly show better durability than live viral infections. In particular, nanoshells containing CpG-ODN and a pair of conserved class I and II major histocompatibility complex-restricted influenza nucleoprotein-derived antigenic peptides are demonstrated to induce near-sterilizing immunity against lethal infections with influenza A viruses of different strains and subtypes in mice, resulting in rapid elimination of replicating viruses. We further examine the pulmonary transport dynamic and optimal composition of the nanoshell vaccine conducive for robust TRM induction as well as the benefit of subcutaneous priming on TRM replenishment. The study presents a practical vaccination strategy for inducing protective TRM-mediated immunity, offering a compelling platform and critical insights in the ongoing quest toward a broadly protective vaccine against universal influenza as well as other respiratory pathogens.

Neutralizing antibody response elicited by SARS-CoV-2 receptor-binding domain.

A safe and effective vaccine candidate is urgently needed for the ongoing COVID-19 pandemic, caused by SARS-CoV-2. Here we report that recombinant SARS-CoV-2 RBD protein immunization in mice is able to elicit a strong antibody response and potent neutralizing capability as measured using live or pseudotyped SARS-CoV-2 neutralization assays.

Emerging lethal infectious bronchitis coronavirus variants with multiorgan tropism.

Infectious bronchitis virus (IBV) causes respiratory diseases in chickens and poses an economic threat to the poultry industry worldwide. Despite vaccine use, there have been field outbreaks of IBV in Taiwan. This study aimed to characterize the emerging IBV variants circulating in Taiwan. The analysis of the structural protein genes showed that these variants emerged through frequent recombination events among Taiwan strains, China strains, Japan strains and vaccine strains. Cross-neutralization tests revealed that two of the variants exhibited novel serotypes. Clinicopathological assessment showed that two of the variants caused high fatality rates of 67% and 20% in one-day-old SPF chicks, and all the variants possessed multiorgan tropisms, including trachea, proventriculus and urogenital tissues. Furthermore, the commercial live-attenuated Mass-type vaccine conferred poor protection against these variants. This study identified novel genotypes, serotypes and pathotypes of emerging IBV variants circulating in Taiwan. There is an urgent need for effective countermeasures against these variant strains.