Antibodies that neutralize cytomegalovirus (CMV) entry into fibroblasts are predominantly directed against epitopes within virion glycoproteins that are required for attachment and entry. However, the mechanism of CMV entry into epithelial and endothelial cells differs from fibroblast entry. Using assays that simultaneously measured neutralizing activities against CMV entry into fibroblasts and epithelial cells, we found that human immune sera and CMV-hyperimmuneglobulins have on average 48-fold higher neutralizing activities against epithelial cell entry compared to fibroblast entry, suggesting that natural CMV infections elicit neutralizing antibodies that are epithelial entry-specific. This activity could not be adsorbed with recombinant gB. The Towne vaccine and the gB/MF59 subunit vaccine induced epithelial entry-specific neutralizing activities that were on average 28-fold (Towne) or 15-fold (gB/MF59) lower than those observed following natural infection. These results suggest that CMV vaccine efficacy may be enhanced by induction of epithelial entry-specific neutralizing antibodies.

In this paper we derive in great detail the formula for count rates of gamma-ray bursts (GRBs) in the framework of fireballs, in terms of the integral of time, where the Doppler effect of the expanding fireball surface is the key factor concerned. Effects arising from the limit on the time delay due to the limited emitting areas on the fireball surface and other factors are investigated. Our analysis shows that the formula for the count rate of fireballs can be expressed as a function of , which is the observation timescale relative to the dynamical timescale of the fireball defined by R c /c, where R c is the fireball radius measured at an associated local time. The profile of light curves of fireballs depends only on the relative timescale, entirely independent of the real timescale and the real size of the objects. It displays in detail how a cutoff tail or a turnover feature (called the cutoff tail problem) in the decay phase of a light curve can arise. This feature is a consequence of a hot spot on the fireball surface, moving toward the observer, and has been observed in a few cases previously. Local pulses suddenly dimming produce light curves bearing a certain decay form (called a standard decay form) and exhibiting a sharp feature at their peaks. Light curves arising from gradually dimming local pulses are smooth at their peaks, and their profiles in the decay phase will obviously deviate from the standard form when the width of the local pulse is large enough. It is observed that light curves arising from relatively short local pulses should be the same, entirely independent of the local pulse shape. The impact of the rest-frame radiation form and of the variance of the form on the profile of light curves is insignificant, while the impact on the magnitude of the light curves is obvious. By performing fits to the count-rate light curves of six sample sources, we show how to obtain some physical parameters from the observed profile of the count rate of GRBs and show that there do exist some GRBs for which the profiles of their count rate light curves can be described by the formula provided. In addition, the analysis reveals that the Doppler effect of fireballs could lead to a power-law relationship between the FWHM of pulses and energy, which has been observed previously by many authors.

Congenital human cytomegalovirus infections are the major infectious cause of birth defects in the United States. How this virus crosses the placenta and causes fetal disease is poorly understood. Guinea pig cytomegalovirus (GPCMV) is a related virus that provides an important model for studying cytomegaloviral congenital transmission and pathogenesis. In order to facilitate genetic analysis of GPCMV, the 232kb GPCMV genome was cloned as an infectious bacterial artificial chromosome (BAC). The BAC vector sequences were flanked by LoxP sites to allow efficient excision using Cre recombinase. All initial clones contained spontaneous deletions of viral sequences and reconstituted mutant viruses with impaired growth kinetics in vitro. The deletions in one BAC were repaired using Escherichia coli genetics. The resulting repaired BAC reconstituted a virus with in vitro replication kinetics identical to the wild type parental virus; moreover, its genome was indistinguishable from that of the wild type parental virus by restriction pattern analysis using multiple restriction enzymes. These results suggest that the repaired BAC is an authentic representation of the complete GPCMV genome. It should provide a valuable tool for evaluating the impact of genetic modifications on the safety and efficacy of live attenuated vaccines and for identifying genes important for congenital transmission and fetal disease.

A sub-array of the Large High Altitude Air Shower Observatory (LHAASO), KM2A is mainly designed to observe a large fraction of the northern sky to hunt for γ-ray sources at energies above 10 TeV. Even though the detector construction is still underway, half of the KM2A array has been operating stably since the end of 2019. In this paper, we present the KM2A data analysis pipeline and the first observation of the Crab Nebula, a standard candle in very high energy γ-ray astronomy. We detect γ-ray signals from the Crab Nebula in both energy ranges of 10 100 TeV and 100 TeV with high significance, by analyzing the KM2A data of 136 live days between December 2019 and May 2020. With the observations, we test the detector performance, including angular resolution, pointing accuracy and cosmic-ray background rejection power. The energy spectrum of the Crab Nebula in the energy range 10-250 TeV fits well with a single power-law function dN/dE = (1.13 0.05 0.08 ) 10 (E/20 TeV) cm s TeV . It is consistent with previous measurements by other experiments. This opens a new window of γ-ray astronomy above 0.1 PeV through which new ultrahigh-energy γ-ray phenomena, such as cosmic PeVatrons, might be discovered.