Adaptive 3D Mesh Steganography Based on Feature-Preserving Distortion.

Current 3D mesh steganography algorithms relying on geometric modification are prone to detection by steganalyzers. In traditional steganography, adaptive steganography has proven to be an efficient means of enhancing steganography security. Taking inspiration from this, we propose a highly adaptive embedding algorithm, guided by the principle of minimizing a carefully crafted distortion through efficient steganography codes. Specifically, we tailor a payload-limited embedding optimization problem for 3D settings and devise a feature-preserving distortion (FPD) to measure the impact of message embedding. The distortion takes on an additive form and is defined as a weighted difference of the effective steganalytic subfeatures utilized by the current 3D steganalyzers. With practicality in mind, we refine the distortion to enhance robustness and computational efficiency. By minimizing the FPD, our algorithm can preserve mesh features to a considerable extent, including steganalytic and geometric features, while achieving a high embedding capacity. During the practical embedding phase, we employ the Q-layered syndrome trellis code (STC). However, calculating the bit modification probability (BMP) for each layer of the Q-layered STC, given the variation of Q, can be cumbersome. To address this issue, we design a universal and automatic approach for the BMP calculation. The experimental results demonstrate that our algorithm achieves state-of-the-art performance in countering 3D steganalysis.

PS-Net: A Learning Strategy for Accurately Exposing the Professional Photoshop Inpainting.

Restoring missing areas without leaving visible traces has become a trivial task with Photoshop inpainting tools. However, such tools have potentially illegal or unethical uses, such as removing specific objects in images to deceive the public. Despite the emergence of many forensics methods of image inpainting, their detection ability is still insufficient when attending to professional Photoshop inpainting. Motivated by this, we propose a novel method termed primary-secondary network (PS-Net) to localize the Photoshop inpainted regions in images. To the best of our knowledge, this is the first forensic method devoted specifically to Photoshop inpainting. The PS-Net is designed to deal with the problems of delicate and professional inpainted images. It consists of two subnetworks: the primary network (P-Net) and the secondary network (S-Net). The P-Net aims at mining the frequency clues of subtle inpainting features through the convolutional network and further identifying the tampered region. The S-Net enables the model to mitigate compression and noise attacks to some extent by increasing the co-occurring feature weights and providing features that are not captured by the P-Net. Furthermore, the dense connection, Ghost modules, and channel attention blocks (C-A blocks) are adopted to further strengthen the localization ability of PS-Net. Extensive experimental results illustrate that PS-Net can successfully distinguish forged regions in elaborate inpainted images, outperforming several state-of-the-art solutions. The proposed PS-Net is also robust against some postprocessing operations commonly used in Photoshop.

Protective immunity induced in mice by multiantigenic DNA vaccine with genes encoding SAG1 and MIC8 of Toxoplasma gondii.

OBJECTIVE: To observe the immunoprotection induced by multiantigenic SAG1-MIC8 DNA vaccine of Toxoplasma gondii in C57BL/6J mice. METHODS: The sequences of genes encoding SAG1 and MIC8 protein were inserted into the eukaryotic expression vector pcDNA3.1 and the multiantigenic recombinant plasmid pcDNA3.1-SAG1-MIC8 was constructed. Then the recombinant plasmid was transfected into Hela cells to test its expression and the recombinant protein characterized by Western blotting 70 mice were divided into 5 groups randomly: PBS, pcDNA3.1, pcDNA3.1-SAG1, pcDNA3.1-MIC8 and pcDNA3.1-SAG1-MIC8. Each mouse was injected intra-muscularly by 100 microg recombinant plasmid for 3 times every two weeks. Mice were bled on day 0, 13, 27, 41, and 55. Four weeks after the final inoculation (on day 56), spleens from seven immunized mice per group were collected. Another seven immunized mice per group were intraperitoneally challenged with 1 x 10(4) tachyzoites of RH T. gondii and the survival time was observed. Serum IgG antibody and cytokines IFN-gamma and IL-4 were demonstrated by ELISA and the T lymphocyte proliferation assay were carried out with 3H-TdR incorporation. RESULTS: Western blotting showed that the mature protein extracts in Hela cells upon transfection with pcDNA3.1-SAG1 (Mr 34,000), pcDNA3.1-MIC8 (Mr 74,000) and pcDNA3.1-SAG1-MIC8 (Mr 109,000) were effectively expressed in cells. The results of IgG antibodies (on day 41 and 55), IgG2b, IgG2c, IFN-gamma (on day 55) and T lymphocyte proliferation assay (on day 56) were more obvious in mice immunized with pcDNA3.1-SAG1-MIC8 multiantigenic DNA vaccine than those in mice with single-gene plasmids (P < 0.05). There was no significant difference in IgG1 and IL-4 levels between vaccinated and control mice after the final inoculation (on day 55) (P > 0.05). The median survival time was 3, 4, 7, 7, and 10d, respectively, with considerable difference among the groups (P < 0.01). CONCLUSION: The multiantigenic DNA vaccine elicits a stronger immuno-protection in mice than the monovalent DNA vaccine.

Evaluation of the immune response elicited by multi-antigenic DNA vaccine expressing SAG1, ROP2 and GRA2 against Toxoplasma gondii.

The parasite Toxoplasma gondii can infect most mammals and birds, sometimes causing severe pathology. Previous studies have reported that multi-antigenic vaccines were more effective than single-antigenic vaccine. It was also reported that the a single-gene vaccine with SAG1 or ROP2, GRA2 could only produce partial protection against T. gondii. In this study, we constructed a multi-antigenic DNA vaccine containing SAG1, ROP2 and GRA2, and evaluated its immune response. We used IL-12 as an adjuvant to enhance the immune response. We immunized BALB/c mice intramuscularly. After immunization, we evaluated the immune response using lymphocyte proliferation assay, cytokine and antibody measurements. The results showed that the group immunized with pcDNA3.1-SAG1-ROP2-GRA2 produced high Th1 immune response compared to other groups immunized with double-gene plasmid, empty plasmid or phosphate-buffered saline, respectively. Moreover, the co-immunization with IL-12 genes enhanced the immune response significantly and prolonged survival time. The current study showed that multi-antigenic DNA with IL-12 produced potent, effective and long-term protection against T. gondii challenge.

Comparison of cholera toxin A2/B and murine interleukin-12 as adjuvants of Toxoplasma multi-antigenic SAG1-ROP2 DNA vaccine.

Toxoplasmosis can lead to severe pathology in both humans and animals. However, an effective vaccine for humans has not been successfully developed. In this study, we used multi-antigenic SAG1-ROP2 as a DNA vaccine and cholera toxin A2/B subunit and murine interleukin-12 to compare their effectiveness as genetic adjuvants. Bagg albino/c (BAL/c) mice were immunized intramuscularly with pcDNA3.1-SAG1-ROP2 alone (control group), or pcDNA3.1-SAG1-ROP2 with co-administration of pCTA2/B or pIL-12, respectively. After immunization, the effectiveness of these two adjuvants were compared using lymphocyte proliferation assay, cytokine and antibody measurements. The group co-administered pIL-12 elicited stronger humoral and Th1-type cellular immune responses than those immunized with pcDNA3.1-SAG1-ROP2 alone, while in the group co-administered pCTA2/B there was no obvious enhancement of immunity. When challenged with Toxoplasma gondii RH strain, mice immunized with pIL-12 co-administration had significantly higher survival rates, whereas there was no notable augmentation of immunity in pCTA2/B group. Therefore, since pIL-12 significantly enhanced the antigenicity of multi-antigenic DNA vaccine, this suggests that IL-12 is a better and more effective adjuvant than CTA2/B in this situation.