Surveillance summary of hospitalized pediatric enterovirus D68 cases in Canada, September 2014.

BACKGROUND: Enterovirus D68 (EV-D68) has been detected infrequently and has not been associated with severe disease in Canada. In the early fall of 2014, following an unusual case increase in the United States, clusters of EV-D68 among children and some adults manifesting severe symptoms were reported in Canada. OBJECTIVE: To provide an initial epidemiological summary of pediatric cases hospitalized with EV-D68 in Canada. METHODS: A time-limited surveillance pilot was conducted collecting information on pediatric cases (less than 18 years of age) hospitalized with EV-D68 between September 1 and 30, 2014. RESULTS: In total, 268 cases were reported from Ontario (n=210), Alberta (n=45), and British Columbia (n=13). Of the 268 reported cases, 64.9% (n=174) were male; the sex difference was statistically significant (p<0.01). Age was reported for 255 cases, with a mean age for males of 5.4 years and for females of 5.3 years. For cases with data available, 6.8% (18/266) were admitted to an intensive care unit. Of those where clinical illness was recorded, respiratory illness alone was present in 98.3% (227/231), neurologic illness alone was present in 0.4% (n=1), and both illnesses were present in 0.9% of cases (n=2); cases with neither respiratory nor neurologic illness were rare (n=1). Of the 90 cases with additional clinical information available, 43.3% were reported as having asthma. No deaths were reported among the 268 cases. CONCLUSION: The EV-D68 outbreak in Canada in September 2014 represents the beginning of a novel outbreak associated with severe illness in children. These findings provide the first epidemiological summary of severe cases of EV-D68 as an emergent respiratory pathogen in Canada. The continued investigation of this pathogen is necessary to build on these results and capture the full spectrum of associated illness.

Discordance in HIV-1 viral loads and antiretroviral drug concentrations comparing semen and blood plasma.

OBJECTIVES: For individuals not on antiretroviral therapy, the risk of heterosexual transmission of HIV appears negligible when blood plasma (BP) viral loads are <1500 HIV-1 RNA copies/mL. It is not clear whether this observation can be extrapolated to individuals on highly active antiretroviral therapy (HAART). Because of differential tissue penetration, antiretroviral drug concentrations may be sufficient to maintain an undetectable viral load in the BP yet not achieve adequate levels to suppress HIV in the genital tract. Therefore, we wanted to correlate HIV viral loads and drug concentrations in semen plasma (SP) and BP. METHODS: Thirty-three men were included. All were on combination antiretroviral therapy with an undetectable BP viral load for at least 1 year. Blood and semen samples were collected within 2 h of each other and tested for HIV RNA by the NucliSens QT (bioMerieux, St Laurent, QC, Canada) method; drug concentrations were determined by liquid chromatography tandem mass spectrometry. RESULTS: Two of the 33 patients (6.1%) with BP viral loads below detection had time-matched HIV viral loads in SP > or =700 copies/mL. Both patients were on efavirenz, the SP concentrations of which were < or =10% of the levels in BP and well below the minimal therapeutic drug monitoring target concentration required to suppress HIV. CONCLUSIONS: Because, at least in part, of poor drug penetration into the genital tract, an undetectable HIV viral load in the BP does not guarantee an undetectable viral load in semen. In view of this, caution should be taken in concluding that patients on HAART with suppressed viraemia are sexually non-infectious.

Short consensus repeat domain 1 of decay-accelerating factor is required for enterovirus 70 binding.

Enterovirus 70 (EV70), like several other human enteroviruses, can utilize decay-accelerating factor (DAF [CD55]) as an attachment protein. Using chimeric molecules composed of different combinations of the short consensus repeat domains (SCRs) of DAF and membrane cofactor protein (CD46), we show that sequences in SCR1 of DAF are essential for EV70 binding. Of the human enteroviruses that can bind to DAF, only EV70 and coxsackievirus A21 require sequences in SCR1 for this interaction.

The HeLa cell receptor for enterovirus 70 is decay-accelerating factor (CD55).

Enterovirus 70 (EV70) is a recently emerged human pathogen belonging to the family Picornaviridae. The ability of EV70 to infect a wide variety of nonprimate cell lines in vitro is unique among human enteroviruses. The importance of virus receptors as determinants of viral host range and tropism led us to study the host cell receptor for this unusual picornavirus. We produced a monoclonal antibody (MAb), EVR1, which bound to the surface of HeLa cells and protected them against infection by EV70 but not by poliovirus or by coxsackievirus B3. This antibody also inhibited the binding of [35S]EV70 to HeLa cells. MAb EVR1 did not bind to monkey kidney (LLC-MK2) cells, nor did it protect these cells against virus infection. In Western immunoassays and in immunoprecipitations, MAb EVR1 identified a HeLa cell glycoprotein of approximately 75 kDa that is attached to the cell membrane by a glycosyl-phosphatidylinositol (GPI) anchor. Decay-accelerating factor (DAF, CD55) is a 70- to 75-kDa GPI-anchored membrane protein that is involved in the regulation of complement and has also been shown to function as a receptor for several enteroviruses. MAb EVR1 bound to Chinese hamster ovary (CHO) cells constitutively expressing human DAF. Anti-DAF MAbs inhibited EV70 binding to HeLa cells and protected them against EV70 infection. Transient expression of human DAF in murine NIH 3T3 cells resulted in binding of labelled EV70 and stably, transformed NIH 3T3 cells expressing DAF were able to support virus replication. These data indicate that the HeLa cell receptor for EV70 is DAF.

Conserved N-terminal sequences in the flagellins of archaebacteria.

Methanococcus voltae produces two flagellins of molecular weight 31,000 and 33,000. Amino acid analysis as well as peptide mapping with cyanogen bromide, chymotrypsin and Staphylococcus aureus V-8 protease indicates that the two flagellins are distinct. N-terminal sequencing of the 31,000 Mc. voltae flagellin as well as the 24,000 and 25,000 molecular weight flagellins of Methanospirillum hungatei GP1 shows an extensive homology with the reported N-terminus of the flagellins from Halobacterium halobium, deduced from the nucleotide sequence of the cloned genes. However, the N-termini of all three sequenced methanogen flagellins lack a terminal methionine and start at position 13 from the N-terminus of H. halobium flagellins. This initial 12 amino acid stretch may be a leader peptide which is subsequently cleaved to generate the mature flagellin, which could suggest flagellar assembly in archaebacteria occurs by a mechanism distinct from that in eubacteria. The high degree of conservation of the N-terminus of the flagellins from Mc. voltae, Msp. hungatei and H. halobium suggests an important role for this sequence, and that the archaebacteria share a common mechanism for flagellar biosynthesis.

Characterization of human placental blood vessel phospholipase A2, demonstration of substrate selectivity for arachidonyl-phosphatidylcholine.

The hydrolysis of acyl esters in phosphatidylcholine by phospholipase A2 (PLA2) for human placental blood vessel was investigated. The enzyme displayed an alkaline pH optimum and an absolute requirement of Ca2+ for activity. In contrast to rat tissues, the human placental blood vessel PLA2 showed a selective preference for arachidonate over linoleate acyl group at the sn-2 position of phosphatidylcholine.