The three-dimensional structure of a self-assembled, recombinant hepatitis E virus particle has been solved to 22-A resolution by cryo-electron microscopy and three-dimensional image reconstruction. The single subunit of 50 kDa is derived from a truncated version of the open reading frame-2 gene of the virus expressed in a baculovirus system. This is the first structure of a T = 1 particle with protruding dimers at the icosahedral two-fold axes solved by cryo-electron microscopy. The protein shell of these hollow particles extends from a radius of 50 A outward to a radius of 135 A. In the reconstruction, the capsid is dominated by dimers that define the 30 morphological units. The outer domain of the homodimer forms a protrusion, which corresponds to the spike-like density seen in the cryo-electron micrograph. This particle retains native virus epitopes, suggesting its potential value as a vaccine.

DIs is a restrictive host range mutant of vaccinia virus strain DIE that grows well only in chick embryo fibroblast cells but is unable to grow in most mammalian cells. In this study, we identified one major deletion (15.4 kbp) which results in the loss of 19 putative open reading frames in the left end of the genome. We then established a system to express foreign genes by inserting them into the deleted region of DIs. We constructed rDIs to express the bacteriophage T7 polymerase (T7pol) gene and showed the expression in various mammalian cell lines by reporter luciferase gene expression under the T7 promoter. We also expressed the full-length human immunodeficiency virus (HIV)-1 NL432 gag gene. The expressed gag gene product induced high levels of cytotoxic T lymphocytes in immunized mice. These data suggest that DIs is useful as an efficient, transient replication-deficient viral vector.

We estimated the genetic parameters related to feed intake (FI), feed efficiency traits (including feed conversion ratio (FCR) and residual feed intake (RFI) of digestible crude protein (DCP) and total digestible nutrients (TDN)), beef marbling score (BMS), melting point of fat (MP) and fatty acid composition. Fat and meat (Musculus trapezius) samples were taken from the carcasses of 863 Japanese Black steers derived from 65 sires, for determination of the MP and fatty acid composition of the total lipid in intramuscular adipose tissue. Genetic parameters were estimated using uni-and bivariate animal models. In addition, pedigree information for 4841 animals was used. Heritability estimates for BMS, MP, individual fatty acids, monounsaturated fatty acids (MUFA), the ratio of saturated fatty acids to MUFA (MUS) and the ratio of elongation (ELONG) were generally high. The FI values of TDN and DCP were also high, but FCRs and RFIs of those were low (0.09 to 0.22). Genetic correlation of BMS with MP was 20.34 (favorable) and with C18:1, MUFA, MUS and ELONG values were 0.40, 0.28, 0.29 and 0.37, respectively (favorable). Genetic correlations of MP with C18:1, MUFA, MUS and ELONG were negative (also favorable) and high (20.85, 20.98, 21.00 (20.996) and 20.66, respectively). The correlation estimates for feed efficiency traits of DCP were quite similar to those of TDN. Genetic correlations of BMS with FCRs and RFIs of TDN and DCP were all positive (unfavorable; 0.21 to 0.51), and in particular, the correlations with RFIs of those were high. The correlations of C18:1, MUFA, MUS and ELONG with RFIs of TDN and DCP were positive (unfavorable) but low (0.06 to 0.17), whereas the corresponding correlations with FCRs of those were all negative (favorable; 20.38 to 20.10). These results suggest that the quantity and quality of beef fat can be simultaneously improved and that the quality of beef fat (fatty acid composition) can be improved directly or indirectly with MP. Furthermore, selecting MP or fatty acid traits does not significantly affect feed efficiency.Keywords: genetic parameter, beef cattle, fatty acid composition, feed efficiency ImplicationsFat quantity and fat quality traits have high heritability estimates and show favorable genetic relationships with each other. Some genetic relationships between fat quality traits and feed efficiency traits are unfavorable, but all of these are weak relationships. These results indicate that it may be convenient to improve fat quality traits genetically and to simultaneously improve the quantity and quality of beef fat. Furthermore, selecting fat quality traits does not significantly affect feed efficiency. We can expect to improve the quality of beef fat without reducing feed utilization efficiency.

The major structural protein of the human polyomavirus BK (BKV), VP1, was expressed by using recombinant baculoviruses. A large amount of protein with a molecular mass of about 42 kDa was synthesized and identified by Western blotting. The protein was detected exclusively in the nuclei by immunofluorescent analysis and it was released into culture medium. The expressed BKV VP1 protein was self-assembled into virus-like particles (BK-VLPs) with two different sizes (50 and 26 nm in diameter), which migrated into four different bands in CsCl gradient with buoyant densities of 1.29, 1.30, 1.33, and 1.35 g/cm(3). The immunological studies on the BK-VLPs suggested that they have similar antigenicity with those of authentic BKV particles. Cryoelectron microscopy and 3D image analysis further revealed that the larger BK-VLPs were composed of 72 capsomers which all were pentamers arranged in a T = 7 surface lattice. This system provides useful information for detailed studies of viral morphogenesis and the structural basis for the antigenicity of BKV.

Initially, virus growth was assayed by indirect immunofluorescence, using a broadly reacting anti-SV40 hamster serum which reacted against cells infected with all members of the Polyomavirus genus. In later experiments, specific anti-LPV serum made in hamsters was used. Cells and medium. Human BJA-B cells, a B-lymphoblastoid line (14), were obtained from C. Yee, National Cancer Institute, Bethesda, Md. The cells were grown in RPMI 1640 medium supplemented with 5% newborn calf serum and antibiotics. After infection with LPV, the cells were maintained in the same medium containing 2% newborn calf serum. FA procedure. Fluorescent antibody (FA) tests were performed as follows. Infected cells were centrifuged at 2,500 rpm for 5 min. The pelleted cells were suspended in a small volume of phosphate-buffered saline (pH 7.2) and smeared onto cover slips. The airdried cover slips were then fixed in acetone-methanol (1:1) for 3 min and dried. The indirect FA procedure with fluorescein-conjugated goat anti-hamster immunoglobulin was used. Preparation of LPV DNA. Viral DNA was extracted from infected BJA-B cells by the method of Hirt (12). Supercoiled form I DNA was separated from viral form II DNA and cellular DNA by the ethidium bromide buoyant density method (20). Cleavage of LPV DNA with restriction endonucleases.