Xpert MTB/XDR: a 10-Color Reflex Assay Suitable for Point-of-Care Settings To Detect Isoniazid, Fluoroquinolone, and Second-Line-Injectable-Drug Resistance Directly from Mycobacterium tuberculosis-Positive Sputum.

We describe the design, development, analytical performance, and a limited clinical evaluation of the 10-color Xpert MTB/XDR assay (CE-IVD only, not for sale in the United States). This assay is intended as a reflex test to detect resistance to isoniazid (INH), fluoroquinolones (FLQ), ethionamide (ETH), and second-line injectable drugs (SLIDs) in unprocessed sputum samples and concentrated sputum sediments which are positive for Mycobacterium tuberculosis The Xpert MTB/XDR assay simultaneously amplifies eight genes and promoter regions in M. tuberculosis and analyzes melting temperatures (Tm s) using sloppy molecular beacon (SMB) probes to identify mutations associated with INH, FLQ, ETH, and SLID resistance. Results can be obtained in under 90 min using 10-color GeneXpert modules. The assay can differentiate low- versus high-level resistance to INH and FLQ as well as cross-resistance versus individual resistance to SLIDs by identifying mutation-specific Tm s or Tm patterns generated by the SMB probes. The assay has a limit of detection comparable to that of the Xpert MTB/RIF assay and successfully detected 16 clinically significant mutations in a challenge set of clinical isolate DNA. In a clinical study performed at two sites with 100 sputum and 214 clinical isolates, the assay showed a sensitivity of 94% to 100% and a specificity of 100% for all drugs except for ETH compared to that of sequencing. The sensitivity and specificity were in the same ranges as those of phenotypic drug-susceptibility testing. Used in combination with a primary tuberculosis diagnostic test, this assay should expand the capacity for detection of drug-resistant tuberculosis near the point of care.

Quantitative Electrochemical DNA Microarray on a Monolith Electrode with Ten Attomolar Sensitivity, 100% Specificity, and Zero Background.

Circulating microRNA are promising diagnostic and prognostic biomarkers of disease in quantitative blood tests. A label-free, PCR-free, electrochemical microarray technology on a monolith electrode is described, with 10 attomolar (aM) sensitivity and responsiveness to binding of <1 zeptomole of target to immobilized ssDNA probes with zero background. Specificity is 100% in a mixture with five nonspecific miRNA each with a 103-fold higher concentration. Direct measurement on plasma-derived miRNA without cDNA conversion and PCR demonstrated multiplexing and near-ideal quantitative correlation with an equivalent pure sample. The dynamic range is a target concentration ranging from 10-2 to 103 femtomolar (fM). This PCR-free novel technology can be applied as a test for cancer diagnosis/prognosis to detect 103 copies of a miRNA sequence in RNA extracted from 100 µL of plasma.

Genetically engineered oncolytic Newcastle disease virus mediates cytolysis of prostate cancer stem like cells.

Oncolytic virotherapy is a promising novel approach that overcomes the limitations posed by radiation and chemotherapy. In this study, the oncolytic efficacy of a recombinant Newcastle disease virus (rNDV) BC-KLQL-GFP, against prostate cancer stem-like/tumor initiating cells was evaluated. Xenograft derived prostaspheres (XPS) induced tumor more efficiently than monolayer cell derived prostaspheres (MCPS) in nude mice. Primary and secondary XPS show enhanced self-renewal and clonogenic potential compared to MCPS. XPS also expressed embryonic stem cell markers, such as Nanog, CD44 and Nestin. Further, prostate specific antigen (PSA) activated recombinant Newcastle Disease Virus (rNDV) was selectively cytotoxic to tumor derived DU145 prostaspheres. An effective concentration (EC50) of 0.11-0.14 multiplicity of infection was sufficient to cause prostasphere cell death in serum free culture. DU145 tumor xenograft derived prostaspheres were used as tumor surrogates as they were enriched for a putative tumor initiating cell population. PSA activated rNDV was efficient in inducing cell death of cells and prostaspheres derived from primary xenografts ex-vivo, thus signifying a potential in vivo efficacy. The EC50 (∼0.1 MOI) for cytolysis of tumor initiating cells was slightly higher than that was required for the parental cell line, but within the therapeutic margin for safety and efficacy.

Genetic characterization of the non-structural protein-3 gene of bluetongue virus serotype-2 isolate from India.

AIM: Sequence analysis and phylogenetic studies based on non-structural protein-3 (NS3) gene are important in understanding the evolution and epidemiology of bluetongue virus (BTV). This study was aimed at characterizing the NS3 gene sequence of Indian BTV serotype-2 (BTV2) to elucidate its genetic relationship to global BTV isolates. MATERIALS AND METHODS: The NS3 gene of BTV2 was amplified from infected BHK-21 cell cultures, cloned and subjected to sequence analysis. The generated NS3 gene sequence was compared with the corresponding sequences of different BTV serotypes across the world, and a phylogenetic relationship was established. RESULTS: The NS3 gene of BTV2 showed moderate levels of variability in comparison to different BTV serotypes, with nucleotide sequence identities ranging from 81% to 98%. The region showed high sequence homology of 93-99% at amino acid level with various BTV serotypes. The PPXY/PTAP late domain motifs, glycosylation sites, hydrophobic domains, and the amino acid residues critical for virus-host interactions were conserved in NS3 protein. Phylogenetic analysis revealed that BTV isolates segregate into four topotypes and that the Indian BTV2 in subclade IA is closely related to Asian and Australian origin strains. CONCLUSION: Analysis of the NS3 gene indicated that Indian BTV2 isolate is closely related to strains from Asia and Australia, suggesting a common origin of infection. Although the pattern of evolution of BTV2 isolate is different from other global isolates, the deduced amino acid sequence of NS3 protein demonstrated high molecular stability.

Pathogenicity and transmission of triple reassortant H3N2 swine influenza A viruses is attenuated following Turkey embryo propagation.

Genetic lineages of swine influenza A viruses (SIVs) have recently been established in Turkeys in the United States. To identify molecular determinants that are involved in virulence and transmission of SIVs to Turkeys, we sequentially passaged two triple reassortant H3N2 SIV isolates from Minnesota in ten day old specific-pathogen free (SPF) Turkey embryos and tested them in seven-day old Turkey poults. We found that SIV replication in Turkey embryos led to minimal mutations in and around the receptor binding and antigenic sites of the HA molecule, while other gene segments were unchanged. The predominant changes associated with Turkey embryo passage were A223V, V226A and T248I mutations in the receptor-binding and glycosylation sites of the HA molecule. Furthermore, Turkey embryo propagation altered receptor specificity in SIV strain 07-1145. Embryo passaged 07-1145 virus showed a decrease in α2, 6 sialic acid receptor binding compared to the wild type virus. Intranasal infection of wild type SIVs in one-week-old Turkey poults resulted in persistent diarrhea and all the infected birds seroconverted at ten days post infection. The 07-1145 wild type virus also transmitted to age matched in-contact birds introduced one-day post infection. Turkeys infected with embryo passaged viruses displayed no clinical signs and were not transmitted to in-contact poults. Our results suggest that Turkey embryo propagation attenuates recent TR SIVs for infectivity and transmission in one week old Turkeys. Our findings will have important implications in identifying molecular determinants that control the transmission and virulence of TR SIVs in Turkeys and other species.

PB1-F2 Protein Does Not Impact the Virulence of Triple-Reassortant H3N2 Swine Influenza Virus in Pigs but Alters Pathogenicity and Transmission in Turkeys.

UNLABELLED: PB1-F2 protein, the 11th influenza A virus (IAV) protein, is considered to play an important role in primary influenza virus infection and postinfluenza secondary bacterial pneumonia in mice. The functional role of PB1-F2 has been reported to be a strain-specific and host-specific phenomenon. Its precise contribution to the pathogenicity and transmission of influenza virus in mammalian host, such as swine, and avian hosts, such as turkeys, remain largely unknown. In this study, we explored the role of PB1-F2 protein of triple-reassortant (TR) H3N2 swine influenza virus (SIV) in pigs and turkeys. Using the eight-plasmid reverse genetics system, we rescued wild-type SIV A/swine/Minnesota/1145/2007 (H3N2) (SIV 1145-WT), a PB1-F2 knockout mutant (SIV 1145-KO), and its N66S variant (SIV 1145-N66S). The ablation of PB1-F2 in SIV 1145 modulated early-stage apoptosis but did not affect the viral replication in swine alveolar macrophage cells. In pigs, PB1-F2 expression did not affect nasal shedding, lung viral load, immunophenotypes, and lung pathology. On the other hand, in turkeys, SIV 1145-KO infected poults, and its in-contacts developed clinical signs earlier than SIV 1145-WT groups and also displayed more extensive histopathological changes in intestine. Further, turkeys infected with SIV 1145-N66S displayed poor infectivity and transmissibility. The more extensive histopathologic changes in intestine and relative transmission advantage observed in turkeys infected with SIV 1145-KO need to be further explored. Taken together, these results emphasize the host-specific roles of PB1-F2 in the pathogenicity and transmission of IAV. IMPORTANCE: Novel triple-reassortant H3N2 swine influenza virus emerged in 1998 and spread rapidly among the North American swine population. Subsequently, it showed an increased propensity to reassort, generating a range of reassortants. Unlike classical swine influenza virus, TR SIV produces a full-length PB1-F2 protein, which is considered an important virulence marker of IAV pathogenicity. Our study demonstrated that the expression of PB1-F2 does not impact the pathogenicity of TR H3N2 SIV in pigs. On the other hand, deletion of PB1-F2 caused TR H3N2 SIV to induce clinical disease early and resulted in effective transmission among the turkey poults. Our study emphasizes the continuing need to better understand the virulence determinants for IAV in intermediate hosts, such as swine and turkeys, and highlights the host-specific role of PB1-F2 protein.