Molecular characterization of an apoptotic strain of Newcastle disease virus isolated from an outbreak in India

Development of an apoptotic lentogenic Newcastle disease virus strain by incorporating the p30 protein of African swine fever virus

Virotherapy is one of the emerging approaches for cancer treatment. Newcastle disease virus (NDV) is a well-studied avian paramyxovirus commonly isolated from birds. Typically, the virulent strains of NDV are acknowledged for their oncolytic properties. The anti-tumor effects of NDV rely on its capacity to trigger apoptosis in cancer cells and elicit inflammatory immune responses against the tumor. However, the virulent strains pose significant challenges for clinical application. This study investigated the development of an apoptotic lentogenic strain of NDV by incorporating the p30 protein gene of the African swine fever virus (ASFV). Previous studies have indicated that the p30 protein interacts with various cellular proteins, including PARP9 and DAB2, which suggests its potential for direct or indirect influence on apoptotic pathways. Our initial data confirmed the upregulation of caspase 3/9, PARP, and cytochrome c, suggesting the pro-apoptotic nature of the p30 protein. Further, a recombinant NDV (rNDV) expressing p30 protein (rNDV-p30) was developed, and its effects were evaluated on human breast cancer (MCF-7) cells. While rNDV alone can't show apoptosis, its variant, rNDV-p30 showed promising apoptotic features in MCF-7 cells. Overall, the results demonstrated the development of rNDV-p30 as an apoptotic virus that offered a novel virotherapy strategy for cancer treatment. Additional research is needed to investigate the underlying mechanisms, safety, and efficacy of the apoptotic activity of the rNDV-p30 and to evaluate the effectiveness of this approach in animal models.

TEX13B is essential for metabolic reprogramming during germ cell differentiation

STUDY QUESTION

What is the functional significance of Tex13b in male germ cell development and differentiation?

SUMMARY ANSWER

Tex13b regulates male germ cell differentiation by metabolic reprogramming during spermatogenesis.

WHAT IS KNOWN ALREADY

Studies in mice and humans suggest that TEX13B is a transcription factor and is exclusively expressed in germ cells.

STUDY DESIGN, SIZE, DURATION

We sequenced the coding regions of TEX13B in 628 infertile men and 427 ethnically matched fertile control men. Further, to identify the molecular function of Tex13b, we created a Tex13b knockout and conditional overexpression system in GC-1spg (hereafter, GC-1) cells.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Our recent exome sequencing study identified novel candidate genes for male infertility. TEX13B was found to be one of the potential candidates, hence we explored the role of TEX13B in male infertility within a large infertile case-control cohort. We performed functional analyses of Tex13b in a GC-1 cell line using CRISPR-Cas9. We differentially labelled the cell proteins by stable isotope labelling of amino acids in cell culture (SILAC) and performed mass spectrometry-based whole-cell proteomics to identify the differential protein regulation in knockout cells compared to wild-type cells. We found that Tex13b knockout leads to downregulation of the OXPHOS complexes and upregulation of glycolysis genes, which was further validated by western blotting. These results were further confirmed by respirometry analysis in Tex13b knockout cells. Further, we also performed a conditional overexpression of TEX13B in GC-1 cells and studied the expression of OXPHOS complex proteins by western blotting.

MAIN RESULTS AND THE ROLE OF CHANCE

We identified a rare variant, rs775429506 (p.Gly237Glu), exclusively in two non-obstructive-azoospermia (NOA) men, that may genetically predispose these men for infertility. Further, we demonstrated that Tex13b functions in the transcription regulation of OXPHOS complexes.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

We examined the function of Tex13b in GC-1 in vitro by knocking out and conditional overexpression, for understanding the function of Tex13b in germ cells. Unfortunately, this could not be replicated in either an animal model or in patient-derived tissue due to the non-availability of an animal model or patient's testis biopsies.

WIDER IMPLICATIONS OF THE FINDINGS

This study identified that Tex13b plays an important role in male germ cell development and differentiation. The findings of this study would be useful for screening infertile males with spermatogenic failure and counselling them before the implementation of assisted reproduction technique(s).

STUDY FUNDING/COMPETING INTEREST(S)

Funding was provided by the Council of Scientific and Industrial Research (CSIR) under the network project (BSC0101 and MLP0113) and SERB, the Department of Science and Technology, Government of India (J C Bose Fellowship: JCB/2019/000027). The authors do not have any competing interest.

Newcastle disease virus mediated apoptosis and migration inhibition of human oral cancer cells: A probable role of β-catenin and matrix metalloproteinase-7

Cancer cell metastasis and its dissemination are most enigmatic and challenging aspects in the development of its therapeutics. Newcastle disease virus (NDV) is a well-studied avian paramyxovirus frequently isolated from birds and rarely from mammals. Since the first report of its oncolytic property, many NDV strains were studied for its effect in various cancer cells. In the present study, NDV strain Bareilly was characterized for its apoptotic potential and migration inhibition in human oral cancer cells. The NDV mediated apoptosis was confirmed by flow cytometry, DNA laddering, and immunoblotting. Moreover, NDV decreased the mitochondrial membrane potential suggesting an intrinsic pathway of apoptosis in oral cancer cells. NDV infection in oral cancer cells results in migration inhibition by a reduction in levels of MMP-7. MMP-7 is one of the key target genes of β-catenin. While overexpression of MMP-7 reversed the inhibitory effect of NDV mediated migration suggested its possible involvement. Wnt/β-catenin is an essential pathway for cell growth, differentiation, and metastasis. The involvement of the Wnt/β-catenin pathway in NDV infection has never been reported. Our results showed that NDV dysregulates Wnt/β-catenin by down-regulation of p-Akt and p-GSK3β leading to degradation of β-catenin. Furthermore, NDV infection leads to a reduction in cytoplasmic and nuclear levels of β-catenin. The study will provide us with a better insight into the molecular mechanism of NDV mediated oncolysis and the key cellular partners involved in the process.

Diphenylethylenediamine-Based Potent Anionophores: Transmembrane Chloride Ion Transport and Apoptosis Inducing Activities

Synthetic anion transporters have been recognized as one of the potential therapeutic agents for the treatment of diseases including cystic fibrosis, myotonia, and epilepsy that originate due to the malfunctioning of natural Cl^- ion transport systems. Recent studies showed that the synthetic Cl^- ion transporters can also disrupt cellular ion-homeostasis and induce apoptosis in cancer cell lines, leading to a revived attention for synthetic Cl^- ion transporters. Herein, we report the development of conformationally controlled 1,2-diphenylethylenediamine-based bis(thiourea) derivatives as a new class of selective Cl^- ion carrier. The strong Cl^- ion binding properties ( K_d = 3.87-6.66 mM) of the bis(thiourea) derivatives of diamine-based compounds correlate well with their transmembrane anion transport activities (EC₅₀ = 2.09-4.15 nM). The transport of Cl^- ions via Cl^-/NO₃^- antiport mechanism was confirmed for the most active molecule. Perturbation of Cl^- ion homeostasis by this anion carrier induces cell death by promoting the caspase-mediated intrinsic pathway of apoptosis.

Emerging variant of genotype XIII Newcastle disease virus from Northeast India

Northeast India with its rich and diverse avifauna acts as a hotbed for emerging virulent Newcastle disease virus (NDV) strains. The present work describes the molecular and pathogenic characterization of NDV strain isolated from Pandu, Assam, India. Clinicopathological and genetic analysis showed the virulent nature of NDV strain Pandu. On molecular phylogenetic and evolutionary distance analysis, the NDV strain Pandu formed a distinct clade within the genotype XIII of class II NDV, suggesting a new sub-genotype XIIIc. The accumulation of mutations in the NDV strain Pandu makes it divergent enough to be considered as a new sub-genotype. The proposed NDV sub-genotype XIIIc consists of strains recently reported from eastern and northeastern India.

Evaluation of the oncolytic potential of R2B Mukteshwar vaccine strain of Newcastle disease virus (NDV) in a colon cancer cell line (SW-620)

Virotherapy is emerging as an alternative treatment of cancer. Among the candidate oncolytic viruses (OVs), Newcastle disease virus (NDV) has emerged as a promising non-engineered OV. In the present communication, we explored the oncolytic potential of R₂B Mukteshwar strain of NDV using SW-620 colon cancer cells. SW-620 cells were xenografted in nude mice and after evaluation of the safety profile, 1 x 10⁷ plaque forming units (PFU) of NDV were inoculated as virotherapeutic agent via the intratumoral (I/T) and intravenous (I/V) route. Tumor growth inhibition was compared with their respective control groups by gross volume and histopathological evaluation. Antibody titer and virus survival were measured by hemagglutination inhibition (HI)/serum neutralization test (SNT) and real-time PCR, respectively. During the safety trial, the test strain did not produce any abnormal symptoms nor weight loss in BALB/c mice. Significant tumor lytic activity was evident when viruses were injected via the I/T route. There was a 43 and 57% tumor growth inhibition on absolute and relative tumor volume basis, respectively, compared with mock control. On the same basis, the I/V route treatment resulted in 40 and 16% of inhibition, respectively. Histopathological examination revealed that the virus caused apoptosis, followed by necrosis, but immune cell infiltration was not remarkable. The virus survived in 2/2 mice until day 10 and in 3/6 mice by day 19, with both routes of administration. Anti-NDV antibodies were generated at moderate level and the titer reached a maximum of 1:32 and 1:64 via the I/T and I/V routes, respectively. In conclusion, the test NDV strain was found to be safe and showed oncolytic activity against the SW-620 cell line in mice.

Synonymous codon usage of genes in polymerase complex of Newcastle disease virus

Newcastle disease virus (NDV) is pathogenic to both avian and non-avian species but extensively finds poultry as its primary host and causes heavy economic losses in the poultry industry. In this study, a total of 186 polymerase complex comprising of nucleoprotein (N), phosphoprotein (P), and large polymerase (L) genes of NDV was analyzed for synonymous codon usage. The relative synonymous codon usage and effective number of codons (ENC) values were used to estimate codon usage variation in each gene. Correspondence analysis (COA) was used to study the major trend in codon usage variation. Analyzing the ENC plot values against GC3s (at synonymous third codon position) we concluded that mutational pressure was the main factor determining codon usage bias than translational selection in NDV N, P, and L genes. Moreover, correlation analysis indicated, that aromaticity of N, P, and L genes also influenced the codon usage variation. The varied distribution of pathotypes for N, P, and L gene clearly suggests that change in codon usage for NDV is pathotype specific. The codon usage preference similarity in N, P, and L gene might be detrimental for polymerase complex functioning. The study represents a comprehensive analysis to date of N, P, and L genes codon usage pattern of NDV and provides a basic understanding of the mechanisms for codon usage bias.

Emergence of a deviating genotype VI pigeon paramyxovirus type-1 isolated from India

Pigeon paramyxovirus type 1 (PPMV-1) is an antigenic variant of avian paramyxovirus type 1 (APMV-1), which infects pigeons. The virus causes high morbidity and mortality, creating an alarming state for the poultry industry. The present work describes the molecular and pathogenic characterization of a PPMV-1 strain isolated from pigeon in Bhopal, India. Complete genome sequence analysis revealed a genome of 15,192 nucleotides encoding six genes organized in the order 3'-N-P-M-F-HN-L-5'. The fusion gene sequence analysis showed the presence of multiple basic amino acids ¹¹²R-R-Q-K-R-F¹¹⁷ at the cleavage site corresponding to pathogenic strains. The mean death time and intracerebral pathogenicity index values indicated a mesogenic nature for the PPMV-1 isolate. On phylogenetic analysis, the strain clustered with genotype VI viruses, including isolates from pigeon and dove. The Bhopal strain showed significant intra and inter-genotype evolutionary distance, suggesting the emergence of a new sub-genotype, VIj.

Evidence of independent evolution of genotype XIII Newcastle disease viruses in India

Despite the prevalence of Newcastle disease virus (NDV) outbreaks in India through the decades, there has been little genetic characterisation of the virulent strains circulating in Northeast India. In 2014, a poultry farm in the Kamrup district of Assam reported an ND outbreak. In this study, genetic analysis and clinicopathological tests showed the virulent nature of the isolate Kamrup. Based on prudent classification criteria, the virulent strain Kamrup was found to be most closely related to members of genotype XIII of class II NDV. A phylogenetic analysis of NDV strains suggested three sub-genotypes: XIIIa, XIIIb and XIIIc. NDV strain Kamrup belonged to sub-genotype XIIIc. Sub-genotype XIIIc isolates were similar to the 1982 isolate from cockatoo and appeared to have evolved parallel to the preceding genotype XIII viruses circulating in India. The high genetic diversity and frequency of mutations observed in the envelope glycoproteins of strain Kamrup demonstrate the evolution of the pandemic genotype XIII NDV in India, which further undermines and complicates of NDV management in India.

Recombinant phosphoprotein based single serum dilution ELISA for rapid serological detection of Newcastle disease virus

Newcastle disease virus (NDV) is the causative agent of a highly contagious disease in avian species. All strains of NDV belong to avian paramyxovirus serotype-1. The disease is endemic in different parts of the world and vaccination is the only way to protect birds from NDV infection. The virus non-structural phosphoprotein (P) is the second most abundant protein and a major modulator of viral replication. Although P protein shows lesser evolutionary divergence among NDV isolates, it is known to be highly divergent among different avian paramyxovirus serotypes. In the present study, a recombinant P protein based single serum dilution ELISA was developed which showed better sensitivity, specificity and accuracy as compared to conventional methods for NDV detection. The recombinant P protein based ELISA could be an alternative to existing diagnostics against NDV infection in chickens.