Multiplex Real-Time Reverse Transcription PCR for Influenza A Virus, Influenza B Virus, and Severe Acute Respiratory Syndrome Coronavirus 2

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in late 2019, and the outbreak rapidly evolved into the current coronavirus disease pandemic. SARS-CoV-2 is a respiratory virus that causes symptoms similar to those caused by influenza A and B viruses. On July 2, 2020, the US Food and Drug Administration granted emergency use authorization for in vitro diagnostic use of the Influenza SARS-CoV-2 Multiplex Assay. This assay detects influenza A virus at 10^2.0, influenza B virus at 10^2.2, and SARS-CoV-2 at 10^0.3 50% tissue culture or egg infectious dose, or as few as 5 RNA copies/reaction. The simultaneous detection and differentiation of these 3 major pathogens increases overall testing capacity, conserves resources, identifies co-infections, and enables efficient surveillance of influenza viruses and SARS-CoV-2.

Detection and discrimination of influenza B Victoria lineage deletion variant viruses by real-time RT-PCR

Background

During the 2016/17 influenza season, influenza B/VIC lineage variant viruses emerged with two (K₁₆₂N₁₆₃) or three (K₁₆₂N₁₆₃D₁₆₄) amino acid (aa) deletions in the haemagglutinin (HA) protein. There are currently five antigenically distinct HA proteins expressed by co-circulating influenza B viruses: B/YAM, B/VIC V1A (no deletion), B/VIC V1A-2DEL (2 aa deletion) and two antigenically distinguishable groups of B/VIC V1A-3DEL (3 aa deletion). The prevalence of these viruses differs across geographical regions, making it critical to have a sensitive, rapid diagnostic assay that detects and distinguishes these influenza B variant viruses during surveillance.

Aim

Our objective was to develop a real-time RT-PCR (rRT-PCR) assay for detection and discrimination of influenza B/VIC lineage variant viruses.

Methods

We designed a diagnostic assay with one pair of conserved primers and three probes specific to each genetic group. We used propagated influenza B/VIC variant viruses and clinical specimens to assess assay performance.

Results

This rRT-PCR assay detects and distinguishes the influenza B/VIC V1A, B/VIC V1A-2DEL, and B/VIC V1A-3DEL variant viruses, with no cross-reactivity. This assay can be run as a multiplex reaction, allowing for increased testing efficiency and reduced cost.

Conclusion

Coupling this assay with the Centers for Disease Control and Prevention’s Human Influenza Virus Real-Time RT-PCR Diagnostic Panel Influenza B Lineage Genotyping Kit results in rapid detection and characterisation of circulating influenza B viruses. Detailed surveillance information on these distinct influenza B variant viruses will provide insight into their prevalence and geographical distribution and could aid in vaccine recommendations.

mTOR regulates skeletal muscle regeneration in vivo through kinase-dependent and kinase-independent mechanisms

Rapamycin-sensitive signaling is required for skeletal muscle differentiation and remodeling. In cultured myoblasts, the mammalian target of rapamycin (mTOR) has been reported to regulate differentiation at different stages through distinct mechanisms, including one that is independent of mTOR kinase activity. However, the kinase-independent function of mTOR remains controversial, and no in vivo studies have examined those mTOR myogenic mechanisms previously identified in vitro. In this study, we find that rapamycin impairs injury-induced muscle regeneration. To validate the role of mTOR with genetic evidence and to probe the mechanism of mTOR function, we have generated and characterized transgenic mice expressing two mutants of mTOR under the control of human skeletal actin (HSA) promoter: rapamycin-resistant (RR) and RR/kinase-inactive (RR/KI). Our results show that muscle regeneration in rapamycin-administered mice is restored by RR-mTOR expression. In the RR/KI-mTOR mice, nascent myofiber formation during the early phase of regeneration proceeds in the presence of rapamycin, but growth of the regenerating myofibers is blocked by rapamycin. Igf2 mRNA levels increase drastically during early regeneration, which is sensitive to rapamycin in wild-type muscles but partially resistant to rapamycin in both RR- and RR/KI-mTOR muscles, consistent with mTOR regulation of Igf2 expression in a kinase-independent manner. Furthermore, systemic ablation of S6K1, a target of mTOR kinase, results in impaired muscle growth but normal nascent myofiber formation during regeneration. Therefore, mTOR regulates muscle regeneration through kinase-independent and kinase-dependent mechanisms at the stages of nascent myofiber formation and myofiber growth, respectively.

Detection of Aeromonas hydrophila in a drinking-water distribution system: a field and pilot study

A 16-month study was conducted on the presence of Aeromonas hydrophila in drinking water in Indiana, U.S.A. Enumeration was conducted in source water, in various sites within a water treatment plant, and in the distribution system in both bulk water and biofilm, as well as in a simulated (annular reactors) drinking-water distribution system. Presumptive Aeromonas spp. counts on source waters regularly approached 10(3)-10(4) CFU/100 mL, during summer months and granular activated carbon - filtered water counts ranged from <1 to 490 CFU/100 mL. In source water, presumptive Aeromonas levels were related to water temperature. Aeromonas hydrophila was never detected in the treatment plant effluent or distributed bulk water, showing disinfectant efficiency on suspended bacteria; however, isolates of A. hydrophila were identified in 7.7% of the biofilm samples, indicating a potential for regrowth and contamination of drinking-water distribution systems.

Establishing an adult congenital heart disease clinic

The majority of babies born with congenital heart disease are now surviving to adulthood. Some have not required cardiac surgery but many have had previous palliation or repair. Because few lesions are "cured" by surgery, these patients need continued expert care to ensure both quality and length of life. Patients need to be treated by physicians with expertise in adult congenital heart disease, with adequate facilities available for both noninvasive and invasive imaging. Access to inpatient facilities also should be available, and a collaborative relationship with pediatric cardiologists, high-risk obstetricians, and anesthesiologists established. Patients need advice regarding endocarditis, employability, exercise, noncardiac surgery, life and health insurance. It is hoped that, with increasing awareness of these patients' problems, adequate lifetime care will be provided for them.

Comparison of magnetic resonance imaging with echocardiography and radionuclide angiography in assessing cardiac function and anatomy following Mustard's operation for transposition of the great arteries

The Mustard operation in infancy and childhood has successfully palliated many patients with transposition of the great arteries who have now survived to adulthood. Right ventricular dysfunction and tricuspid regurgitation are important determinants of late morbidity and mortality. The value of noninvasive magnetic resonance imaging (MRI) in the assessment of cardiac function and anatomy 9 to 20 years after this procedure has been investigated, and compared with findings on echocardiography, radionuclide ventriculography and angiography in 17 adult patients. Ejection fractions measured by MRI were higher compared with radionuclide ventriculography. The correlation for the left ventricle was closer (r = 0.75) than for the right ventricle (r = 0.49). Tricuspid regurgitation was assessed by Doppler echocardiography and by MRI using the right/left ventricular stroke volume ratio. The mean stroke volume ratio in those with Doppler evidence of tricuspid regurgitation was 1.6:1 compared to 1.1:1 in those without, and this difference reached significance (p less than 0.01). The anatomy of the great arteries was clearly visible in all patients. Five patients had a residual ventricular septal defect which, with the exception of 1 small defect, was easily visualized. The intraatrial baffle was best seen in transverse slices, and the systemic venous connection showed as a relatively narrow channel lying in the posterior part of the cavity. In general, baffle anatomy was easier to assess on 2-dimensional echocardiography.(ABSTRACT TRUNCATED AT 250 WORDS)

Double mitral valve orifice in atrioventricular defects

Eleven patients with double mitral valve orifice and atrioventricular defects were studied, and the diagnosis proven by open heart surgery. The correct preoperative diagnosis was suggested by a characteristic angiographic appearance of the medial border of the left ventricle. M-mode echocardiography may show the two orifices which are better seen on two dimensional echocardiography. Two operative deaths occurred in patients with a slightly obstructive valve, and one late death followed mitral valve replacement. Eight patients did well after minor repair to a cleft, or leaving the valve untouched. Occasionally a double mitral orifice, if disorganised and slightly stenotic, may cause early deterioration in a patient with an otherwise uncomplicated ostium primum defect. The surgeon should be forewarned of this mitral anomaly since simple repair may be difficult.

Treatment of chronic heart failure with pirbuterol: acute haemodynamic responses

Fifty-nine patients with severe chronic heart failure were given pirbuterol, a beta agonist with vasodilator and positive inotropic properties. The acute haemodynamic responses to both single (20 patients) and incremental doses (39 patients) were measured. Pirbuterol increased cardiac index and reduced left ventricular filling pressure and systemic vascular resistance with only small changes in heart rate and blood pressure. Maximal effects were observed at an average of 170 minutes after a single oral dose of pirbuterol. In the incremental dose studies the plasma pirbuterol concentration was found to increase with increasing doses and was related to the magnitude of the haemodynamic response. Pirbuterol was well tolerated, and no drug-related side effects were recorded. Oral pirbuterol clearly improved pump performance in these patients, the haemodynamic changes being consistent with vasodilatation as the dominant mechanism rather than a direct inotropic effect.

Cardiac pain at rest. Management and follow-up of 100 consecutive cases

One hundred consecutive patients, admitted to the coronary care unit with cardiac pain at rest but no evidence of recent myocardial infarction have been followed up for nine to 26 (mean 14) months. They were treated initially with bed rest, beta-adrenergic blockade, and nitrates. In 54 patients pain subsided within 24 hours. Coronary angiography was carried out in 46. Thirty-five had coronary artery lesions and three had spasm in normal coronary arteries. One had hypertrophic cardiomyopathy and seven had normal findings. Seventeen patients with previous angina and severe coronary disease were operated on, with one death and one perioperative infarction; two died late, 12 were symptom free, and two had angina. Seven of 18 patients treated medically had recurrent angina and underwent operation. Of the 11 unoperated patients, one died, three had angina, and seven were symptom free. Two of the eight patients who were not catheterised developed infarction, four had angina, and three were symptom free. Recurrent pain continued for more than 24 hours in 46 patients, and all underwent angiography. Forty-three had coronary artery disease and 34 underwent early bypass surgery; there were two operative deaths and three perioperative infarctions. Twenty-six symptom free at follow-up. Of the nine unoperated patients with coronary disease, four developed infarction, two were operated on for recurrent angina, two were symptom free, and one had mild angina. Optimal management of patients with pain at rest can be determined only with knowledge of the coronary artery anatomy and of left ventricular function. Many respond initially to intensive medical treatment and coronary angiography can be performed electively. In those with continuing pain, urgent angiography is required and can be done safely.

Mechanical haemolytic anaemia after valve repair operations for non-rheumatic mitral regurgitation

Two cases are described in which severe mechanical haemolytic anaemia developed shortly after operation for repair of non-rheumatic mitral regurgitation. One patient had a "floppy" valve and the other cleft mitral leaflets, and both had chordal rupture. In both there was residual regurgitation after repair though in one this was initially only trivial. Clinically manifest haemolysis ceased after replacement of the valve by a frame-mounted xenograft. There are two previously reported cases in which haemolytic anaemia followed an unsuccessful mitral valve repair operation. Subclinical haemolysis or mild haemolytic anaemia may occur with unoperated valve lesions, but hitherto frank haemolytic anaemia has been observed only when turbulent blood flow is associated with the presence of a prosthetic valve or patch of prosthetic fabric. In these four cases, however, polyester or Teflon sutures were the only foreign material, and it is suggested that when these are used for the repair of leaflets, particularly in non-rheumatic mitral valve disease, they may increase the damaging effect of turbulence on circulating red blood cells.