Structural Insight into Paramyxovirus and Pneumovirus Entry Inhibition.

Paramyxoviruses and pneumoviruses infect cells through fusion (F) protein-mediated merger of the viral envelope with target membranes. Members of these families include a range of major human and animal pathogens, such as respiratory syncytial virus (RSV), measles virus (MeV), human parainfluenza viruses (HPIVs), and highly pathogenic Nipah virus (NiV). High-resolution F protein structures in both the metastable pre- and the postfusion conformation have been solved for several members of the families and a number of F-targeting entry inhibitors have progressed to advanced development or clinical testing. However, small-molecule RSV entry inhibitors have overall disappointed in clinical trials and viral resistance developed rapidly in experimental settings and patients, raising the question of whether the available structural information may provide a path to counteract viral escape through proactive inhibitor engineering. This article will summarize current mechanistic insight into F-mediated membrane fusion and examine the contribution of structural information to the development of small-molecule F inhibitors. Implications are outlined for future drug target selection and rational drug engineering strategies.

Improving Pneumovirus Isolation Using a Centrifugation and AZD1480 Combined Method.

The isolation of respiratory viruses, especially from clinical specimens, often shows poor efficiency with classical cell culture methods. The lack of suitable methods to generate virus particles inhibits the development of diagnostic assays, treatments, and vaccines. We compared three inoculation methods, classical cell culture, the addition of a JAK2 inhibitor AZD1480, and centrifugation-enhanced inoculation (CEI), to replicate human respiratory syncytial virus (HRSV) and human metapneumovirus (HMPV). In addition, a combined method using AZD1480 treatment and CEI was used on throat swabs to verify that this method could increase virus isolation efficiency from human clinical specimens. Both CEI and AZD1480 treatment increased HRSV and HMPV genome replication. Also, the combined method using CEI and AZD1480 treatment enhanced virus proliferation synergistically. The combined method is particularly suited for the isolation of interferon-sensitive or slowly growing viruses from human clinical specimens.

Apoptosis in pneumovirus infection.

Pneumovirus infections cause a wide spectrum of respiratory disease in humans and animals. The airway epithelium is the major site of pneumovirus replication. Apoptosis or regulated cell death, may contribute to the host anti-viral response by limiting viral replication. However, apoptosis of lung epithelial cells may also exacerbate lung injury, depending on the extent, the timing and specific location in the lungs. Differential apoptotic responses of epithelial cells versus innate immune cells (e.g., neutrophils, macrophages) during pneumovirus infection can further contribute to the complex and delicate balance between host defense and disease pathogenesis. The purpose of this manuscript is to give an overview of the role of apoptosis in pneumovirus infection. We will examine clinical and experimental data concerning the various pro-apoptotic stimuli and the roles of apoptotic epithelial and innate immune cells during pneumovirus disease. Finally, we will discuss potential therapeutic interventions targeting apoptosis in the lungs.

In vitro effects of some steroidal hormones on the replication of avian pneumovirus.

The effects of testosterone, oestradiol, progesterone and cortisone on the in vitro replication of avian pneumovirus in tracheal organ cultures (TOC) were investigated. Samples of cell-associated and cell-free virus from TOC, grown in medium containing these hormones, were taken at selected intervals. Progesterone and cortisone caused a slight increase in cell-associated virus. Testosterone and oestradiol caused a slight delay and decrease in virus replication when compared with the controls. All groups shared the same time interval to reach peak cell-free virus titre, 96 h post inoculation. In comparison with the controls, only a small drop (0.25-0.50 log10) in the peak of virus titre was observed in the hormone treated groups.

Susceptibility of an avian pneumovirus isolated from Minnesota turkeys to physical and chemical agents.

Survival characteristics of a Minnesota avian pneumovirus (APV) isolated from a turkey nasoturbinate, propagated in tissue culture, and exposed to various physiochemical treatments were determined. These characteristics included survivability under various conditions. Specifically, APV was viable at temperatures of -70 C and -20 C for over 26 wk, 4 C for less than 12 wk, 20 C for less than 4 wk, 37 C for 48 hr, and 50 C for less than 6 hr. In addition, APV survived 12 freeze/thaw cycles with no loss of activity. With a variable pH for 1 hr, the titer was unaffected between the levels of pH 5 and 9. Several disinfectants, including quaternary ammonia, ethanol, iodophor, a phenol derivative, a biguanide, and bleach, were all effective in reducing the viability of the virus. After 7 days of drying at room temperature, the APV remained viable and was recovered on cell culture.