应用新城疫病毒治疗肿瘤的研究进展

新城疫病毒可以特异地杀伤肿瘤细胞,而对正常细胞没有伤害,目前在临床实验中认为是安全、有效的溶瘤试剂。随着近年来反向遗传操作技术的日趋成熟,该技术开始应用到新城疫病毒溶瘤效果的优化方面,通过改造新城疫病毒的F基因,及表达重组粒细胞巨噬细胞集落刺激因子,干扰素-γ,白细胞介素-2和肿瘤坏死因子-α等肿瘤杀伤因子,使该病毒具备更加优越的肿瘤杀伤能力,成为肿瘤治疗领域一个新兴的亮点,为癌症的临床治疗提供了崭新的前景。以下将简要介绍应用反向遗传操作技术重组新城疫病毒优化肿瘤治疗效果的研究进展,以及本实验室在相关领域的研究情况。     

Oncolytic Newcastle disease virus reduces growth of cervical cancer cell by inducing apoptosis

Although Oncolytic viruses have been regarded as a promising tool for targeted therapy of cancer, accomplishing high efficacy and specificity with this strategy is challenging. Oncolytic virotherapy is one of the novel therapeutic methods recently used for the therapy of human malignancies. Cervical cancer is on the major public health problem and the second most common cause of cancer death among females in less developed countries. The aim of this study was mainly to determine the apoptosis effect of oncolytic Newcastle disease virus (NDV) in TC-1 cell line.In the current study, the oncolytic NDV, vaccine strain LaSota, was used to infect murine TC-1 cells of human papillomavirus (HPV)-associated carcinoma which expressing human papillomavirus 16 (HPV-16) E6/E7 antigens in vitro. The effectiveness of NDV for cervical cancer cell line was investigated by evaluating the antitumor activity of oncolytic NDV and the involved mechanisms. Antitumor activities of oncolytic NDV were assessed by cell proliferation (MTT) and lactate dehydrogenase (LDH) release analysis. In addition, molecular changes of early stage of apoptosis and the role of reactive oxygen species (ROS) were analyzed by flow cytometry and Western Blot in NDV-treated TC-1 cells.The results showed that NDV treatment significantly decreased the viability of a TC-1 cell line and suppressed the growth by inducing apoptotic cell death. In addition, we demonstrated that NDV-induced apoptosis of TC-1 cells is mediated by ROS production. In summary, our findings suggest that oncolytic NDV is a possible therapeutic candidate as a selective antitumor agent for the treatment of cervical cancer.     

Oncolytic specificity of Newcastle disease virus is mediated by selectivity for apoptosis-resistant cells

Newcastle disease virus (NDV) is a negative-sense RNA virus that has been shown to possess oncolytic activity. NDV's selective replication in tumor cells has been previously suggested to be due to the lack of a proper antiviral response in these cells. Here we demonstrate that NDV possesses oncolytic activity in tumor cells capable of a robust type I interferon (IFN) response, suggesting that another mechanism underlies NDV's tumor specificity. We show that the oncolytic selectivity of NDV for tumor cells is dependent upon tumor cell resistance to apoptosis. Utilizing the human non-small-cell lung cancer cell line A549 overexpressing the antiapoptotic protein Bcl-xL, we show significant enhancement of oncolytic activity and NDV replication. Interestingly, while the Bcl-xL-overexpressing cells were resistant to apoptotic stimuli induced by chemotherapeutic agents and early viral replication, during the subsequent viral cycles, we observed a paradoxical increase in apoptosis in response to NDV. The increased oncolytic activity seen was secondary to enhanced viral replication and syncytium formation. The induction of a type I IFN response was enhanced in Bcl-xL cells. Overall, these findings propose a new mechanism for cancer cell specificity for NDV, making it an attractive anticancer agent for chemoresistant tumors with enhanced antiapoptotic activity.     

Reduced Newcastle disease virus-induced oncolysis in a subpopulation of cisplatin-resistant MCF7 cells is associated with survivin stabilization

ABSTRACT: BACKGROUND: Cisplatin resistance is a serious problem in cancer treatment. To overcome it, alternative approaches including virotherapy are being pursued. One of the candidates for anticancer virotherapy is the Newcastle disease virus (NDV). Even though NDV's oncolytic properties in various cancer cells have been widely reported, information regarding its effects on cisplatin resistant cancer cells is still limited. Therefore, we tested the oncolytic efficacy of a strain of NDV, designated as AF2240, in a cisplatin-resistant breast cancer cell line. METHODS: Cisplatin-resistant cell line (MCF7-CR) was developed from the MCF7 human breast adenocarcinoma cell line by performing a seven-cyclic exposure to cisplatin. Following NDV infection, fluorescence-activated cell sorting (FACS) analysis and immunoblotting were used to measure cell viability and viral protein expression, respectively. Production of virus progeny was then assessed by using the plaque assay technique. RESULTS: Infection of a mass population of the MCF7-CR with NDV resulted in 50% killing in the first 12 hours post-infection (hpi), comparable to the parental MCF7. From 12 hpi onwards, the remaining MCF7-CR became less susceptible to NDV killing. This reduced susceptibility led to increased viral protein synthesis and virus progeny production. The reduction was also associated with a prolonged cell survival via stabilization of the survivin protein. CONCLUSIONS: Our findings showed for the first time, the involvement of survivin in the reduction of NDV-induced oncolysis in a subpopulation of cisplatin-resistant cells. This information will be important towards improving the efficacy of NDV as an anticancer agent in drug resistant cancers.     

Newcastle disease virus exerts oncolysis by both intrinsic and extrinsic caspase-dependent pathways of cell death

Newcastle disease virus (NDV), an avian paramyxovirus, is tumor selective and intrinsically oncolytic. Here, we present evidence that genetically modified, recombinant NDV strains are cytotoxic to human tumor cell lines of ecto-, endo-, and mesodermal origin. We show that cytotoxicity against tumor cells is due to multiple caspase-dependent pathways of apoptosis independent of interferon signaling competence. The signaling pathways of NDV-induced, cancer cell-selective apoptosis are not well understood. We demonstrate that NDV triggers apoptosis by activating the mitochondrial/intrinsic pathway and that it acts independently of the death receptor/extrinsic pathway. Caspase-8-methylated SH-SY5Y neuroblastoma cells are as sensitive to NDV as other caspase-8-competent cells. This demonstrates that NDV is likely to act primarily through the mitochondrial death pathway. NDV infection results in the loss of mitochondrial membrane potential and the subsequent release of the mitochondrial protein cytochrome c, but the second mitochondrion-derived activator of caspase (Smac/DIABLO) is not released. In addition, we describe early activation of caspase-9 and caspase-3. In contrast, cleavage of caspase-8, which is predominantly activated by the death receptor pathway, is a TNF-related, apoptosis-inducing ligand (TRAIL)-induced late event in NDV-mediated apoptosis of tumor cells. Our data, therefore, indicate that the death signal(s) generated by NDV in tumor cells ultimately converges at the mitochondria and that it acts independently of the death receptor pathway. Our cytotoxicity studies demonstrate that recombinant NDV could be developed as a cancer virotherapy agent, either alone or in combination with therapeutic transgenes. We have also shown that trackable oncolytic NDV could be developed without any reduction in oncolytic efficacy.     

Type I Interferon-Sensitive Recombinant Newcastle Disease Virus for Oncolytic Virotherapy

Newcastle disease virus (NDV), an avian paramyxovirus, is tumor selective and intrinsically oncolytic because of its potent ability to induce apoptosis. Several studies have demonstrated that NDV is selectively cytotoxic to tumor cells but not normal cells due to defects in the interferon (IFN) antiviral responses of tumor cells. Many naturally occurring strains of NDV have an intact IFN-antagonistic function and can still replicate in normal human cells. To avoid potential toxicity issues with NDV, especially in cancer patients with immunosuppression, safe NDV-oncolytic vectors are needed. We compared the cell killing abilities of (i) a recombinant NDV (rNDV) strain, Beaudette C, containing an IFN-antagonistic, wild-type V protein (rBC), (ii) an isogenic recombinant virus with a mutant V protein (rBC-Edit virus) that induces increased IFN in infected cells and whose replication is restricted in normal human cells, and (iii) a recombinant LaSota virus with a virulent F protein cleavage site that is as interferon sensitive as rBC-Edit virus (LaSota V.F. virus). Our results indicated that the tumor-selective replication of rNDV is determined by the differential regulation of IFN-α and downstream antiviral genes induced by IFN-α, especially through the IRF-7 pathway. In a nude mouse model of human fibrosarcoma, we show that the IFN-sensitive NDV variants are as effective as IFN-resistant rBC virus in clearing the tumor burden. In addition, mice treated with rNDV exhibited no signs of toxicity to the viruses. These findings indicate that augmentation of innate immune responses by NDV results in selective oncolysis and offer a novel and safe virotherapy platform.Several naturally occurring or engineered oncolytic viruses are emerging as novel tools for selective growth in and killing of a variety of tumor cells (1, 21, 34, 41). It has been consistently reported that during tumor evolution, diminished interferon (IFN) responsiveness coevolves as a frequent genetic defect (4, 31, 32, 41). Any defects in responsiveness to interferon will afford permissiveness of tumors for replication of oncolytic viruses by blunting the antiviral innate immune system. Thus, it was suggested that oncolytic viruses could be engineered to induce strong IFN response and/or to be defective in antagonizing the IFN signaling. This would result in virus replication in tumor cells with IFN defects but in reduced or crippled virus replication in normal cells, with the absence of toxicity (42). A variety of oncolytic viruses have been engineered to exploit tumor-specific genetic defects (3, 12, 24, 42, 46) and shown to be potent oncolytic agents.Newcastle disease virus (NDV), an avian paramyxovirus, is a promising broad-spectrum oncolytic agent (27, 29, 30, 37). Nonengineered, naturally occurring strains of NDV such as 73-T (6), MTH68 (7), PV701 (28, 35), and NDV-HUJ (11) have been successfully employed in several clinical studies for tumor regression. NDV is inherently oncolytic and tumor selective, sparing normal cells (9, 15, 37). The tumor selectivity of NDV is considered to be due to a defective IFN response in tumor cells (10, 23, 37). NDV is a strong inducer of type I IFN in many types of cells (18). In normal cells, a robust IFN-mediated antiviral response limits the replication of NDV (9, 23). This known sensitivity of NDV to cellular antiviral mechanisms affords a wide safety margin for its use in humans.Recent studies have indicated that improved therapeutic vectors of NDV could be engineered through reverse genetics for enhanced oncolytic efficacy from an increased anti-tumor response and interleukin 2 (IL-2) receptor-mediated targeting (5, 9, 44, 46). Therefore, we reasoned that recombinant NDVs (rNDVs) that are susceptible to cellular innate immune responses would be safer and more effective oncolytic agents. Even though NDV is an avian virus and induces a strong IFN response in normal human cells, it still expresses IFN-antagonizing activity. Ablation of the expression of V protein, which is responsible for this anti-IFN activity, may further reduce the ability of NDV to infect and kill normal human cells without affecting tumor cell infection and lysis. Here, we describe the relative oncolytic efficacies of three rNDV strains differing in IFN antagonism. The rNDV variants with an IFN-sensitive phenotype had parallel therapeutic efficacies in xenotransplanted human fibrosarcoma cells in a nude mouse model and offer great potential as recombinant vectors in therapy of human malignancies.     

Incorporation of Host Complement Regulatory Proteins into Newcastle Disease Virus Enhances Complement Evasion

Newcastle disease virus (NDV), an avian paramyxovirus, is inherently tumor selective and is currently being considered as a clinical oncolytic virus and vaccine vector. In this study, we analyzed the effect of complement on the neutralization of NDV purified from embryonated chicken eggs, a common source for virus production. Fresh normal human serum (NHS) neutralized NDV by multiple pathways of complement activation, independent of neutralizing antibodies. Neutralization was associated with C3 deposition and the activation of C2, C3, C4, and C5 components. Interestingly, NDV grown in mammalian cell lines was resistant to complement neutralization by NHS. To confirm whether the incorporation of regulators of complement activity (RCA) into the viral envelope afforded complement resistance, we grew NDV in CHO cells stably transfected with CD46 or HeLa cells, which strongly express CD46 and CD55. NDV grown in RCA-expressing cells was resistant to complement by incorporating CD46 and CD55 on virions. Mammalian CD46 and CD55 molecules on virions exhibited homologous restriction, since chicken sera devoid of neutralizing antibodies to NDV were able to effectively neutralize these virions. The incorporation of chicken RCA into NDV produced in embryonated eggs similarly provided species specificity toward chicken sera.     

新城疫病毒抗肿瘤效应机制的研究现状

溶瘤病毒疗法是一种重要的抗癌手段。经研究,新城疫病毒(Newcastlediseasevirus,NDV)是一种非常有效的溶瘤病毒(oncolyticvirus,OV),它能选择性杀伤肿瘤细胞,对正常细胞几乎无影响。本文从NDV诱导肿瘤细胞发生凋亡、自噬、抑制细胞代谢、刺激机体免疫反应和诱导肿瘤细胞发生核糖体应激反应等方面综述了新城疫病毒的抗肿瘤效应机制,并着重探讨了NDV通过诱导核糖体压力应激反应调控肿瘤细胞翻译系统并诱导细胞发生凋亡的具体机制,旨在为今后NDV抗肿瘤作用的深入研究及靶向治疗癌症提供更加扎实丰富的理论基础。     

Parenteral vaccination of mammalian livestock with Newcastle disease virus-based vector vaccines offers optimal efficacy and safety

Newcastle disease virus (NDV) is an avian virus that is being evaluated as a vaccine vector for the delivery of foreign genes in mammals. The use of NDV as a vaccine vector in these species offers two major advantages. First, NDV is highly attenuated in mammals, rendering its use inherently safe. Second, mammals lack pre-existing NDV immunity, which minimizes the risk of vaccination failure. NDV-vector vaccines are generally administered to mammals via the respiratory route. We recently showed that intramuscular vaccination with NDV-based Rift Valley fever virus (RVFV) vaccines provides complete protection in mice and induces neutralizing antibodies in sheep and cattle, the main target species of RVFV. Here, we discuss the use of NDV as a vaccine vector for applications in mammalian livestock with an emphasis on the vaccination route. We also report the results of novel experiments that underscore our notion that vaccination via a parenteral route is more effective than immunization via the respiratory route.     

NDV‐D90 inhibits 17β‐estradiol‐mediated resistance to apoptosis by differentially modulating classic and nonclassic estrogen receptors in breast cancer cells

Newcastle disease virus (NDV) is endowed with the oncolytic ability to kill tumor cells, while rarely causing side effects in normal cells. Both estrogen receptor α (ERα) and the G protein estrogen receptor (GPER) modulate multiple biological activities in response to estrogen, including apoptosis in breast cancer (BC) cells. Here, we investigated whether NDV‐D90, a novel strain isolated from natural sources in China, promoted apoptosis by modulating the expression of ERα or the GPER in BC cells exposed to 17β‐estradiol (E2). We found that NDV‐D90 significantly killed the tumor cell lines MCF‐7 and BT549 in a time‐ and dose‐dependent manner. We also found that NDV‐D90 exerted its effects on the two cell lines mainly by inducing apoptosis but not necrosis. NDV‐D90 induced apoptosis via the intrinsic and extrinsic signaling pathways in MCF‐7 cells (ER‐positive cells) during E2 exposure not only by disrupting the E2/ERα axis and enhancing GPER expression but also by modulating the expression of several apoptosis‐related proteins through ERα‐and GPER‐independent processes. NDV‐D90 promoted apoptosis via the intrinsic signaling pathway in BT549 cells (ER‐negative cells), possibly by impairing E2‐mediated GPER expression. Furthermore, NDV‐D90 exerted its antitumor effects in vivo by inducing apoptosis. Overall, these results demonstrated that NDV‐D90 promotes apoptosis by differentially modulating the expression of ERα and the GPER in ER‐positive and negative BC cells exposed to estrogen, respectively, and can be utilized as an effective approach to treating BC.     

Accessory genes define the relationship between the herpes simplex virus and its host

Accessory genes of herpes simplex virus are implicated in the interplay between the virus and host responses to infection, ensuring the survival of the virus in the host and maintaining its transmission cycle in human populations. They will provide vital clues about novel vaccination strategies and gene and oncolytic therapies.     

Novel oncolytic viruses: Riding high on the next wave?

The use of viruses as targeted cancer therapy has shown significant promise, and the list of oncolytic viruses continue to grow. The interest in unexplored viruses as oncolytic agents is a natural corollary to the successes and challenges of those already being examined in the clinical setting. Are these ‘new’ viruses any more effective than their predecessors? What are the benefits of refining current clinical candidates compared to searching for new ones? This review briefly describes some of these novel oncolytic viruses. It also examines the issues that arise in comparing them to each other. We believe that the viral mechanism of action is a key factor to success and suggest guidelines by which all oncolytic virus candidates could be evaluated.     

p53-independent endoplasmic reticulum stress-mediated cytotoxicity of a Newcastle disease virus strain in tumor cell lines

While Newcastle disease virus (NDV) causes serious infections in birds, it is apparently nonpathogenic in mammalian species, including humans. Previous observations and small-scale clinical trials indicated that NDV exerts oncolytic effects. Isolates of NDV were found to have selective affinity to transformed cells. We previously showed that the attenuated NDV strain MTH-68/H causes apoptotic cell death in cultures of PC12 rat pheochromocytoma cells. The aim of the present study was to extend MTH-68/H cytotoxicity testing with human tumor cell lines and to analyze certain biochemical aspects of its oncolytic effect. MTH-68/H was found to be able to kill a wide range of transformed cells by apoptosis. While caspase-8 and caspase-9 are not involved in MTH-68/H-induced apoptosis, activation of caspase-3 and caspase-12 was detected in virus-infected PC12 cells. A human glioblastoma cell line with repressible expression of the p53 protein did not show any difference in MTH-68/H sensitivity in its p53-expressing and p53-depleted states, indicating that the apoptotic process induced by MTH-68/H does not depend on p53. Apoptosis was accompanied by virus replication in two tumor cell lines tested (PC12 cells and HeLa human cervical cells), and signs of endoplasmic reticulum stress (phosphorylation of protein kinase R-like endoplasmic reticulum kinase and eIF2alpha) were also detected in transformed cells. In contrast, proliferation of nontransformed mouse and rat fibroblast cell lines and human primary fibroblasts was not affected by MTH-68/H treatment. MTH-68/H thus selectively kills tumor cell cultures by inducing endoplasmic reticulum stress leading to p53-independent apoptotic cell death.     

Cancer and viruses: a double-edged sword

Oncovirus, synonymously called a 'tumour virus', is a virus that can cause cancer. An oncolytic virus preferentially infects the host's cancer cells and lyses them, causing tumour destruction, and is thus referred to as a 'cancer killing virus'. With an estimated 11% of cancer-associated deaths caused by oncoviruses and the possibility that many cancers may be treated by using oncolytic viruses, the role of viruses in cancer may be viewed as a double-edged sword. A total of seven human cancer viruses have been identified as oncoviruses, having been associated with various cancers. Conversely, a large number of oncolytic viruses have shown great potential towards the treatment of certain types of cancer. Proteomics has now been applied towards understanding the complex interplay that exists between oncoviruses and the immune responses that serve to prevent oncoviral diseases. This review attempts to summarise the neoplastic potential of human tumour associated viruses and associated vaccine successes. The potential use of oncolytic viruses for the therapeutic intervention of cancer will also be discussed. Finally, this review will discuss the enormous potential of proteomics technology in the field of oncovirology.     

Differentially regulated interferon response determines the outcome of Newcastle disease virus infection in normal and tumor cell lines

Newcastle disease virus (NDV) is a negative-strand RNA virus with oncolytic activity against human tumors. Its effectiveness against tumors and safety in normal tissue have been demonstrated in several clinical studies. Here we show that the spread of NDV infection is drastically different in normal cell lines than in tumor cell lines and that the two cell types respond differently to beta interferon (IFN-beta) treatment. NDV rapidly replicated and killed HT-1080 human fibrosarcoma cells but spread poorly in CCD-1122Sk human skin fibroblast cells. Pretreatment with endogenous or exogenous IFN-beta completely inhibited NDV replication in normal cells but had little or no effect in tumor cells. Thus, the outcome of NDV infection appeared to depend on the response of uninfected cells to IFN-beta. To investigate their differences in IFN responsiveness, we analyzed and compared the expression and activation of components of the IFN signal transduction pathway in these two types of cells. The levels of phosphorylated STAT1 and STAT2 and that of the ISGF3 complex were markedly reduced in IFN-beta-treated tumor cells. Moreover, cDNA microarray analysis revealed significantly fewer IFN-regulated genes in the HT-1080 cells than in the CDD-1122Sk cells. This finding suggests that tumor cells demonstrate a less-than-optimum antiviral response because of a lesion in their IFN signal transduction pathway. The rapid spread of NDV in HT-1080 cells appears to be caused by their deficient expression of anti-NDV proteins upon exposure to IFN-beta.     

Overexpression of Newcastle disease virus (NDV) V protein enhances NDV production kinetics in chicken embryo fibroblasts

Newcastle disease virus (NDV) is not only one of the most economically important pathogen of poultry but also has a potential as anticancer virotherapy. The role of NDV V protein in virus-production kinetics was investigated using DF-1 cell-based production system. The presence of an anti-interferon (IFN)-alpha antibody resulted in enhanced NDV production kinetics in a dose-dependent manner by blocking binding of NDV-induced IFN to its receptor. To prepare DF-1 cell whose cellular IFN signaling is blocked efficiently, stable cell lines expressing either lentogenic or velogenic NDV V protein known as an IFN antagonist were established. The overexpression of NDV V protein enhanced NDV production kinetics and expedited the rate of NDV production, while it had no effect on Japanese encephalitis virus production. NDV V protein functions as an IFN antagonist by inhibiting the increase in type I IFNs by NDV infection. The IFN signals in cells expressing NDV V protein were weakened by decreased activation or expression of the dsRNA-activated enzymes. These IFN antagonist activities enhance rapid virus replication and spread in the early phase of viral infection and will be useful in improving the production of viral vaccine strains.     

基于痘苗病毒载体的恶性肿瘤基因治疗研究进展

基因治疗一直是肿瘤生物治疗的重要策略,而以溶瘤痘苗病毒为载体的肿瘤治疗近年来受到较多关注。该文总结了目前用于恶性肿瘤治疗的痘苗病毒和基于痘苗病毒载体的基因治疗研究进展及其在各个领域的成果。     

Genomic characterisation of two virulent Newcastle disease viruses isolated from crested ibis (Nipponia nippon) in China

This paper describes the complete genomic sequences of two virulent Newcastle disease virus (NDV) isolates, Shaanxi06 (prevalent genotype VIId) and Shaanxi10 (novel sub-genotype VIi), from sick crested ibises. The genomes of both isolates were 15,192 nt long and consisted of six genes in the order of 3′-NP-P-M-F-HN-L-5′. The genomes of the two isolates were highly similar to other reference NDV strains. However, some unique features were found in the HN protein of Shaanxi06 and the F gene end of Shaanxi10. Shaanxi06 and Shaanxi10 shared the same virulent motif ^112 −R-R-Q-K-R-F^− 117 at the F protein cleavage site, which coincided with previous pathogenicity test results. Phylogenetic analysis revealed that both isolates were clustered within class II NDV, with Shaanxi06 in genotype VII and Shaanxi10 in genotype VI. Both isolates shared high homology with the prevalent genotype NDV strains that circulate in fowls and waterfowls. This study is the first to provide genomic information about a novel sub-genotype VIi NDV strain and another genotype VIId virus, which will be useful for subsequent investigations.     

溶瘤病毒靶向治疗肿瘤的策略

近年来,随着国内外几款溶瘤病毒制剂的相继上市,溶瘤病毒疗法成为肿瘤免疫治疗的焦点。溶瘤病毒可选择性感染并裂解肿瘤细胞,同时释放肿瘤相关抗原激活机体的抗肿瘤免疫反应,达到杀伤肿瘤细胞和抑制肿瘤生长的目的。溶瘤病毒对肿瘤的靶向杀伤作用决定了其安全性和溶瘤效果。为了开发出安全高效的溶瘤病毒,目前主要采用以下策略：利用某些病毒载体对肿瘤细胞的天然靶向性,使溶瘤病毒选择性地在肿瘤细胞内复制并杀伤肿瘤细胞;或者对病毒基因组进行缺失和插入等修饰,通过靶向肿瘤细胞特异性表面受体、胞内信号通路或者肿瘤微环境等提高溶瘤病毒的肿瘤靶向性。其中,肿瘤微环境中的低氧状态、新血管生成以及免疫抑制状态等都可成为溶瘤病毒的靶点。而溶瘤病毒通过表达细胞因子和免疫检查点抑制剂,或者与CAR-T细胞联合作用,靶向调节肿瘤微环境中免疫抑制状态,成为提高溶瘤病毒肿瘤靶向性的常用方法。本文将对以上溶瘤病毒靶向治疗肿瘤策略的研究进展进行综述。