Correction: King et al. Establishing an In Vitro System to Assess How Specific Antibodies Drive the Evolution of Foot-and-Mouth Disease Virus. Viruses 2022, 14, 1820.

In the original publication [...].

Establishing an In Vitro System to Assess How Specific Antibodies Drive the Evolution of Foot-and-Mouth Disease Virus.

Viruses can evolve to respond to immune pressures conferred by specific antibodies generated after vaccination and/or infection. In this study, an in vitro system was developed to investigate the impact of serum-neutralising antibodies upon the evolution of a foot-and-mouth disease virus (FMDV) isolate. The presence of sub-neutralising dilutions of specific antisera delayed the onset of virus-induced cytopathic effect (CPE) by up to 44 h compared to the untreated control cultures. Continued virus passage with sub-neutralising dilutions of these sera resulted in a decrease in time to complete CPE, suggesting that FMDV in these cultures adapted to escape immune pressure. These phenotypic changes were associated with three separate consensus-level non-synonymous mutations that accrued in the viral RNA-encoding amino acids at positions VP266, VP280 and VP1155, corresponding to known epitope sites. High-throughput sequencing also identified further nucleotide substitutions within the regions encoding the leader (Lpro), VP4, VP2 and VP3 proteins. While association of the later mutations with the adaptation to immune pressure must be further verified, these results highlight the multiple routes by which FMDV populations can escape neutralising antibodies and support the application of a simple in vitro approach to assess the impact of the humoral immune system on the evolution of FMDV and potentially other viruses.

The RNA pseudoknots in foot-and-mouth disease virus are dispensable for genome replication, but essential for the production of infectious virus.

Non-coding regions of viral RNA (vRNA) genomes are critically important in the regulation of gene expression. In particular, pseudoknot (PK) structures, which are present in a wide range of RNA molecules, have a variety of roles. The 5' untranslated region (5' UTR) of foot-and-mouth disease virus (FMDV) vRNA is considerably longer than in other viruses from the picornavirus family and consists of a number of distinctive structural motifs that includes multiple (2, 3 or 4 depending on the virus strain) putative PKs linked in tandem. The role(s) of the PKs in the FMDV infection are not fully understood. Here, using bioinformatics, sub-genomic replicons and recombinant viruses we have investigated the structural conservation and importance of the PKs in the FMDV lifecycle. Our results show that despite the conservation of two or more PKs across all FMDVs, a replicon lacking PKs was replication competent, albeit at reduced levels. Furthermore, in competition experiments, GFP FMDV replicons with less than two (0 or 1) PK structures were outcompeted by a mCherry FMDV wt replicon that had 4 PKs, whereas GFP replicons with 2 or 4 PKs were not. This apparent replicative advantage offered by the additional PKs correlates with the maintenance of at least two PKs in the genomes of FMDV field isolates. Despite a replicon lacking any PKs retaining the ability to replicate, viruses completely lacking PK were not viable and at least one PK was essential for recovery of infections virus, suggesting a role for the PKs in virion assembly. Thus, our study points to roles for the PKs in both vRNA replication and virion assembly, thereby improving understanding the molecular biology of FMDV replication and the wider roles of PK in RNA functions.

Management of Acute Decompensated Heart Failure in Rural Versus Metropolitan Settings: An Australian Experience.

BACKGROUND: Acute decompensated heart failure (ADHF) is the most common cause of hospital admission in patients over 65, with poorer outcomes demonstrated in rural versus metropolitan areas. The aim of this study was to compare the in-hospital and post-discharge management of ADHF patients admitted to rural versus metropolitan hospitals in Victoria. METHODS: Data from the Victorian Cardiac Outcomes Registry, Heart Failure (VCOR-HF) project was used. This was a prospective, observational, non-randomised study of consecutive patients admitted to participating hospitals in Victoria, Australia, with ADHF as their primary diagnosis over four 30-day periods during consecutive years. All patients were followed up for 30 days post discharge. RESULTS: 1,357 patients (1,260 metropolitan, 97 rural) were admitted to study hospitals with ADHF during the study periods. Cohorts were similar in age (average 76.87±13.12 yrs) and percentage of male gender (56.4% overall). Metropolitan patients were more likely to have diabetes (44.4% vs 34.0%, p=0.046), kidney disease (65.8% vs 37.1%, p<0.01) and anaemia (31.9% vs 19.6%, p=0.01). There was no significant difference in length of stay between metropolitan and rural patients (7.49 vs 6.37 days, p=0.12). There was no significant difference between metropolitan and rural patients in 30-day rehospitalisations (19.1% vs 11.6%, p=0.07, respectively) and all-cause 30-day mortality (8.2% vs 4.1%, p=0.15, respectively). Metropolitan patients were significantly more likely to have seen their general practitioner (GP) (68.1% vs 53.2%, p<0.01) or attend an outpatient clinic (35.9% vs 10.6%, p<0.01) by 30 days. There was no significant difference in number of days to follow-up of any kind between groups. Referrals to a heart failure home visiting program remained low overall (19.9%). CONCLUSION: There was no significant difference in 30-day rehospitalisations or mortality between patients admitted to rural versus metropolitan hospitals. Geographical discrepancies were noted in follow-up by 30 days, with significantly more metropolitan patients having seen a doctor by 30 days post-discharge. Overall follow-up rates remain suboptimal.

No association of G-protein-coupled receptor kinase 5 or ß-adrenergic receptor polymorphisms with Takotsubo cardiomyopathy in a large Australian cohort.

AIMS: Takotsubo cardiomyopathy (TC) is an increasingly recognized syndrome in which patients present with chest pain and ST changes, and are observed to have reversible LV apical ballooning in the absence of angiographically significant coronary artery stenosis. Although the pathophysiology remains unclear, the syndrome occurs almost exclusively in women, and is often triggered by stress. Recent small studies have reported association of TC with functional variants in the G-protein-coupled receptor kinase 5 (GRK5) gene, as well as in the ß1-adrenergic receptor (ß1AR) and ß2AR. METHODS AND RESULTS: We tested these associations in a larger cohort of 92 TC patients. In addition we examined for the association of polymorphisms in the oestrogen receptor α (ERα) and catechol-O-methyl transferase (COMT) with the occurrence of TC, by comparing the allele frequency of these variants in the TC cohort with that in previously genotyped large Caucasian cohorts. Ninety-two patients with TC were recruited from four Australian centres; they had an age range of 41-90 years (mean ± SD = 66.3 ± 9) and 89/92 were female. There were no significant differences in allelic frequency in the TC group vs. the historic control database for any of the loci. CONCLUSION: In the largest genotyped TC cohort in the literature, we have found no association of genetic variants in the ERα, ß1AR, ß2AR, or COMT genes, or with the previously implicated GRK5, with occurrence of the syndrome.