[Diagnostic efficacy of an ultrasound quantitative method in a rat model of experimental liver fibrosis].

To evaluate the efficacy of an ultrasound-based quantitative method to diagnose liver fibrosis using a rat model. Ultrasonography was performed on the livers of 90 Sprague-Dawley rats with or without thioacetamide-induced fibrosis. The liver capsule thickness and 13 texture parameters of gray level co-occurrence matrix were extracted from the standard sonograms. After sacrifice, severity of liver fibrosis (S0-S4 classification) was diagnosed by histopathology. Analysis of variance and correlation statistical tests were used to analyze the differences between groups and determine the relationships between each of the 14 quantitative ultrasound index points and the histological results, respectively. Discriminant analysis models were developed for quantitative diagnosis of liver fibrosis, and the leave-one-case-out method was used to verify the efficiency of models. All 14 indices were significantly correlated with the histological stages of fibrosis (P less than 0.05). The accuracy of the discriminant model for S0, S1, S2, S3 and S4 was 83.3%, 84.2%, 70.0%, 50.0% and 88.2%, respectively. In addition, 73.3% of cross-validated rats were accurately classified. Grouping S0 as no fibrosis, S1 as mild fibrosis, S2 with S3 as moderate to severe fibrosis and S4 as early cirrhosis increased the accuracy of the discriminant model for these four groups (respectively, 91.7%, 84.2%, 69.0% and 88.2%) and allowed for 78.9% of cross-validated rats to be correctly identified. Ultrasonography combined with texture analysis was a novel and accurate method to diagnose liver fibrosis in a rat model; further studies may provide insights into its applicability for quantitating liver fibrosis in other animal models or in clinic.

Identification, Characterization, and Distribution of Southern rice black-streaked dwarf virus in Vietnam.

A novel dwarf and twisting syndrome first observed on rice in Nghe An Province, Vietnam, in 2009 has spread rapidly to the other 19 provinces of North and Central Vietnam. Infected rice plants showed stunting, darkening of leaves, twisting of leaf tips, and splitting of leaf margins. At a later stage, white waxy enations that eventually turned black were observed on the underside of leaf blades, leaf sheaths, and culms. The disease also infected maize after rice was harvested. Infected maize plants were stunted and dark green with small enations along the minor veins on the back of leaves. The disease agent has now been identified as Southern rice black-streaked dwarf virus (SRBSDV) recently reported from Southern China. Typical fijivirus viroplasms containing crystalline arrayed spherical virions approximately 70 to 75 nm in diameter were observed under the electron microscope in ultrathin sections of infected rice leaves. The virus was transmitted to rice and maize seedlings by the white-backed planthopper (Sogatella furcimera). A one-step reverse transcription-polymerase chain reaction (RT-PCR) protocol was used to confirm the presence of SRBSDV in 477 samples of rice or maize from 29 provinces among 5 agroecological regions in North and Central Vietnam. Rice black-streaked dwarf virus was not detected in these samples. Partial sequences of RNA segments 4 and 10 from several isolates showed very low genetic divergences between isolates from Vietnam and China, suggesting a common origin, and phylogenetic analysis confirmed the placement of SRBSDV as a distinct virus within subgroup 2 of the genus Fijivirus.

A recombinant pseudorabies virus encoding the HA gene from H3N2 subtype swine influenza virus protects mice from virulent challenge.

The hemagglutinin (HA) gene of A/Swine/Inner Mogolian/547/2001 (H3N2) swine influenza virus (SIV) was recombined into the genome of pseudorabies virus (PRV) Bartha-K61 vaccine strain, generating a recombinant PRV expressing the HA gene, designated as rPRV-HA. One group of 15 mice was inoculated intranasally (i.n.) with 10(5.0) PFU of rPRV-HA, and another two control groups of mice (15 mice per group) were mock-inoculated or inoculated with Bartha-K61. Mice inoculated with rPRV-HA developed hemagglutination inhibition antibodies 3 weeks post-inoculation. Twenty-eight days post-inoculation, all mice were challenged i.n. with 10(5.0) TCID50 of A/Swine/Heilongjiang/74/2000 (H3N2). No challenge virus was isolated from vaccinated mice, and mild pathological lesions were observed only in lungs following challenge. The results demonstrate that the recombinant rPRV-HA expressing the HA gene from H3N2 SIV can protect mice from heterologous virulent challenge, and may represent a candidate vaccine against SIV.

Construction and characterization of a recombinant pseudorabies virus expressing porcine reproductive and respiratory syndrome virus GP5.

The GP5 gene of porcine reproductive and respiratory syndrome virus (PRRSV) was integrated into the TK gene locus of pseudorabies virus (PRV) vaccine strain Bartha-K61, resulting in a TK- and gE- negative recombinant PRV harboring GP5 gene, designated as rPRV-GP5. The in vitro expression of the GP5 by rPRV-GP5-infected cells was analyzed by single-step growth analysis,Western blot,and indirect immunofluorescence test. It was shown that GP5 gene can be expressed authentically in the cytoplasm of rPRV-GP5-infected cells. Compared to its parental virus, rPRV-GP5 showed no obvious difference regarding viral replication and cytopathogenic effects in several cell cultures. Four PRV-negative sheep immunized intramuscularly with 10(6.0) PFU of rPRV-GP5 were fully protected from challenge with 10(3) LD50 of highly virulent PRV S strain of porcine origin. Ten PRV- and PRRSV-negative piglets given intranasally with 10(7.0) PFU of rPRV-GP5 and challenged intranasally with 10(5.0) TCID50 of virulent PRRSV CH-1a strain at day 63 post-inoculation developed antibodies against PRRSV 3, 5, 14 days post-challenge, as revealed by indirect immunofluorescence test, enzyme-linked immunosorbent assay and virus neutralization test. The results suggest that rPRV-GP5 is capable of inducing anamnestic immune response to PRRS in inoculated animals.

Measurement of spectral maximum shift of ultrasonic backscatter signals in cancellous bone.

The feasibility of assessing cancellous bone from the Spectral Maximum Shift (SMS) of the backscattered ultrasonic signal is investigated. And the SMS of backscatter signals from bovine tibiae cancellous bone in vitro were measured and discussed. The spectral maximum of the backscattered signal downshift with increases of the apparent density of cancellous bone. When the bone suffered from osteoporosis, the density will reduce. Therefore, compared with the backscattered signal spectrum in the normal cancellous bone, the osteoporotic cancellous bones have small SMS of backscattered signal. According to the size of SMS, the status of cancellous bone and the degree of osteoporotic fracture risk may be assessed. On the other hand, techniques based on ultrasonic backscatter offer the advantage that only one ultrasonic transducer rather than two transducers is required to perform measurements. The operation of measurement is convenient and simple in assessment of cancellous bone status and diagnosis of osteoporosis.