Genomic epidemiology reveals multiple introductions of Zika virus into the United States

Zika virus (ZIKV) is causing an unprecedented epidemic linked to severe congenital abnormalities. In July 2016, mosquito-borne ZIKV transmission was reported in the continental United States; since then, hundreds of locally acquired infections have been reported in Florida. To gain insights into the timing, source, and likely route(s) of ZIKV introduction, we tracked the virus from its first detection in Florida by sequencing ZIKV genomes from infected patients and Aedes aegypti mosquitoes. We show that at least 4 introductions, but potentially as many as 40, contributed to the outbreak in Florida and that local transmission is likely to have started in the spring of 2016-several months before its initial detection. By analysing surveillance and genetic data, we show that ZIKV moved among transmission zones in Miami. Our analyses show that most introductions were linked to the Caribbean, a finding corroborated by the high incidence rates and traffic volumes from the region into the Miami area. Our study provides an understanding of how ZIKV initiates transmission in new regions

Genetic mechanisms of critical illness in COVID-19.

Host-mediated lung inflammation is present1, and drives mortality2, in the critical illness caused by coronavirus disease 2019 (COVID-19). Host genetic variants associated with critical illness may identify mechanistic targets for therapeutic development3. Here we report the results of the GenOMICC (Genetics Of Mortality In Critical Care) genome-wide association study in 2,244 critically ill patients with COVID-19 from 208 UK intensive care units. We have identified and replicated the following new genome-wide significant associations: on chromosome 12q24.13 (rs10735079, P = 1.65 × 10-8) in a gene cluster that encodes antiviral restriction enzyme activators (OAS1, OAS2 and OAS3); on chromosome 19p13.2 (rs74956615, P = 2.3 × 10-8) near the gene that encodes tyrosine kinase 2 (TYK2); on chromosome 19p13.3 (rs2109069, P = 3.98 ×  10-12) within the gene that encodes dipeptidyl peptidase 9 (DPP9); and on chromosome 21q22.1 (rs2236757, P = 4.99 × 10-8) in the interferon receptor gene IFNAR2. We identified potential targets for repurposing of licensed medications: using Mendelian randomization, we found evidence that low expression of IFNAR2, or high expression of TYK2, are associated with life-threatening disease; and transcriptome-wide association in lung tissue revealed that high expression of the monocyte-macrophage chemotactic receptor CCR2 is associated with severe COVID-19. Our results identify robust genetic signals relating to key host antiviral defence mechanisms and mediators of inflammatory organ damage in COVID-19. Both mechanisms may be amenable to targeted treatment with existing drugs. However, large-scale randomized clinical trials will be essential before any change to clinical practice

Molecular Pathogenesis of EBV Susceptibility in XLP as Revealed by Analysis of Female Carriers with Heterozygous Expression of SAP

X-linked lymphoproliferative disease (XLP) is a primary immunodeficiency caused by mutations in SH2D1A which encodes SAP. SAP functions in signalling pathways elicited by the SLAM family of leukocyte receptors. A defining feature of XLP is exquisite sensitivity to infection with EBV, a B-lymphotropic virus, but not other viruses. Although previous studies have identified defects in lymphocytes from XLP patients, the unique role of SAP in controlling EBV infection remains unresolved. We describe a novel approach to this question using female XLP carriers who, due to random X-inactivation, contain both SAP+ and SAP− cells. This represents the human equivalent of a mixed bone marrow chimera in mice. While memory CD8+ T cells specific for CMV and influenza were distributed across SAP+ and SAP− populations, EBV-specific cells were exclusively SAP+. The preferential recruitment of SAP+ cells by EBV reflected the tropism of EBV for B cells, and the requirement for SAP expression in CD8+ T cells for them to respond to Ag-presentation by B cells, but not other cell types. The inability of SAP− clones to respond to Ag-presenting B cells was overcome by blocking the SLAM receptors NTB-A and 2B4, while ectopic expression of NTB-A on fibroblasts inhibited cytotoxicity of SAP− CD8+ T cells, thereby demonstrating that SLAM receptors acquire inhibitory function in the absence of SAP. The innovative XLP carrier model allowed us to unravel the mechanisms underlying the unique susceptibility of XLP patients to EBV infection in the absence of a relevant animal model. We found that this reflected the nature of the Ag-presenting cell, rather than EBV itself. Our data also identified a pathological signalling pathway that could be targeted to treat patients with severe EBV infection. This system may allow the study of other human diseases where heterozygous gene expression from random X-chromosome inactivation can be exploited

Genome sequencing reveals Zika virus diversity and spread in the Americas

Although the recent Zika virus (ZIKV) epidemic in the Americas and its link to birth defects have attracted a great deal of attention, much remains unknown about ZIKV disease epidemiology and ZIKV evolution, in part owing to a lack of genomic data. Here we address this gap in knowledge by using multiple sequencing approaches to generate 110 ZIKV genomes from clinical and mosquito samples from 10 countries and territories, greatly expanding the observed viral genetic diversity from this outbreak. We analysed the timing and patterns of introductions into distinct geographic regions; our phylogenetic evidence suggests rapid expansion of the outbreak in Brazil and multiple introductions of outbreak strains into Puerto Rico, Honduras, Colombia, other Caribbean islands, and the continental United States. We find that ZIKV circulated undetected in multiple regions for many months before the first locally transmitted cases were confirmed, highlighting the importance of surveillance of viral infections. We identify mutations with possible functional implications for ZIKV biology and pathogenesis, as well as those that might be relevant to the effectiveness of diagnostic tests

Method for detecting Salmonella species by assaying outer membrane Porin F (ompF)

The invention relates to a method of detecting the presence of Salmonella in a sample using novel oligonucleotide sequences. Also presented is a kit for putting the method into practice and novel nucleic acid sequences for ompF. The ompF gene was found to be 100% inclusive for Salmonella species and 100% exclusive for non-Salmonella species for the strains tested thus making it an excellent marker for identification of both the species of Salmonella: S. enterica and S. bongori. Two hundred and eighteen isolates belonging to Salmonella enterica (subspecies I-VI) and Salmonella bongori were examined using novel primers designed to detect the ompF gene. The target was present in all the 218 Salmonella isolates including all the subspecies of Salm. enterica and Salm. bongori. The ompF gene was absent in 180 non-Salmonella strains tested

Kit for detecting Salmonella species by assaying outer membrane porin F (ompF)

The invention relates to a method of detecting the presence of Salmonella in a sample using novel oligonucleotide sequences. Also presented is a kit for putting the method into practice and novel nucleic acid sequences for ompF. The ompF gene was found to be 100% inclusive for Salmonella species and 100% exclusive for non-Salmonella species for the strains tested thus making it an excellent marker for identification of both the species of Salmonella: S. enterica and S. bongori. Two hundred and eighteen isolates belonging to Salmonella enterica (subspecies I-VI) and Salmonella bongori were examined using novel primers designed to detect the ompF gene. The target was present in all the 218 Salmonella isolates including all the subspecies of Salm. enterica and Salm. bongori. The ompF gene was absent in 180 non-Salmonella strains tested

Kit for detecting Salmonella species by assaying outer membrane porin F (ompF)

The invention relates to a method of detecting the presence of Salmonella in a sample using novel oligonucleotide sequences. Also presented is a kit for putting the method into practice and novel nucleic acid sequences for ompF. The ompF gene was found to be 100% inclusive for Salmonella species and 100% exclusive for non-Salmonella species for the strains tested thus making it an excellent marker for identification of both the species of Salmonella: S. enterica and S. bongori. Two hundred and eighteen isolates belonging to Salmonella enterica (subspecies I-VI) and Salmonella bongori were examined using novel primers designed to detect the ompF gene. The target was present in all the 218 Salmonella isolates including all the subspecies of Salm. enterica and Salm. bongori. The ompF gene was absent in 180 non-Salmonella strains tested

Comparison of Methods for DNA Isolation from Food Samples for Detection of Shiga Toxin-Producing Escherichia coli by Real-Time PCR

In this study, food samples were intentionally contaminated with Escherichia coli O157:H7, and then DNA was isolated by using four commercial kits. The isolated DNA samples were compared by using real-time PCR detection of the Shiga toxin genes. The four kits tested worked similarly

Community-Associated Methicillin-Resistant Staphylococcus aureus Epidemic Clone USA300 in Isolates from Florida and Washington

We examined 299 methicillin-resistant, community-associated Staphylococcus aureus isolates from Florida and Washington State for the presence of the USA300 epidemic clone. Pulsed-field gel electrophoresis demonstrated the epidemic clone in 43% of our S. aureus strains and in isolates from both states. The majority of the USA300 isolates (88%) were from wound infections