Indian Journal of Virology最新文献

The HN and L gene sequences of an Indian isolate of Newcastle disease virus was analyzed prior to and after exposure to 56 °C at tenth passage and fifteenth passage to study the variations at molecular level. In the HN gene sequence of progenitor and thermostable strain, substitution of K373I, F374L, M516R, D517V were considered to contribute to the increase in the stability of the protein. In the L gene of the thermostable strain, variations were observed at many positions and among these the substitutions at position P675H K677R, K893D, R1132K, had charged amino acids, and at L656A, F657V, F869L, T886I, M899I, G1131V, V1675L, had hydrophobic amino acids that could be related to increased stability of L protein at high temperatures. The changes in amino acid sequence in HN and L gene of the thermostable strain might render structural variations that might have contributed to the stability of the strain at higher temperature.

The coat protein (CP) sequences of twelve Papaya ringspot virus (PRSV) (pathotype-P) isolates from six major papaya growing areas were determined and compared with those of published PRSV. The CP coding region varied in size from 846-852 nucleotides, encoding a protein of 282-284 amino acids. Comparative CP sequence analysis revealed that the PRSV-P isolates originating from Bangladesh were divergent up to 14 % at amino acids level. Further, the isolates from Bangladesh shared 86-95 % amino acid sequence identity with those reported from rest 21 of the Asia and 83-93 % amino acid sequence identity with isolates from the other parts of the world. A number of KE repeats were observed in the N terminus of the CP coding region of all Bangladesh isolates. Phylogenetic branching pattern revealed that the PRSV-P isolates originating from Bangladesh formed a distinct clade from those from the rest of the world. This forms the first report on the genetic diversity of PRSV-P isolates from Bangladesh.

Cucumber mosaic virus (CMV) has a wide host range causing severe damage in many important agricultural and ornamental crops. Earlier reports showed the prevalence of CMV subgroup I isolates in India. However, some recent reports point towards increasing incidence of subgroup II isolates in the country. The complete genome of a CMV isolate causing severe mosaic in cucumber was characterized and its phylogenetic analysis with other 21 CMV isolates reported worldwide clustered it with subgroup II strains. The genome comprised of RNA 1 (3,379 nucleotides), RNA 2 (3,038 nucleotides) and RNA 3 (2,206 nucleotides). The isolate showed highest homology with subgroup II isolates: 95.1-98.7, 87.7-98.0, and 85.4-97.1 % within RNA1, RNA2, and RNA3, respectively. RNA1 and RNA2 were closely related to the Japanese isolate while RNA3 clustered with an American isolate. Host range studies revealed that isolate showed severe mosaic symptoms on Nicotiana spp. and Cucumis spp. The isolate induced leaf deformation and mild filiform type symptoms in tomato. To best of our knowledge this is the first report of complete genome of CMV subgroup II isolate from India.

A PCR based method for detection of viral DNA in nucleopolyhedrovirus of three lepidopterans, Spodoptera litura, Amsacta albistriga and Helicoverpa armigera, was developed by employing the late expression factor-8 (lef-8) gene of three NPV using specific primers. The amplicons of 689, 699 and 665 bp were amplified, respectively, and the nucleotide sequences were submitted to GenBank and the accession numbers were obtained. The sequences of lef-8 gene of S. litura NPV and H. armigera NPV matched with those of their respective references in the GenBank database, thereby confirming their identity, however, the sequence of A. albistriga NPV was the first sequence submitted to the GenBank database. The sequence similarity analysis between the three lef-8 gene of NPV sequenced in the present study revealed that there was no significant similarity between them, however A. albistriga NPV and S. litura NPV were found to be closely related. CLUSTAL alignment of the sequences generated revealed general relatedness among NPVs lef-8 gene. The study confirmed that lef-8 gene can be used for quick and correct discriminatory identification of insect viruses.

Japanese encephalitis virus (JEV) causes severe viral encephalitis in humans and some other mammalian animals. Highly efficient culture of the virus is critical for antigen preparation, vaccine production and other basic researches. We have investigated the influence of a number of variables such as the strain virulence, the state of the host cells, medium composition, infection method and others on the proliferation of distinct JEV strains in BHK-21 cells. The results showed that two distinct strategies are needed for the propagation of virulent or attenuated JEV strains. The most critical variables were the method of infection, and especially the density of the host cell. Our studies indicate the general approaches to the in vitro culture of other JEV strains using BHK-21 cell line.

Newcastle disease (ND) is a fatal and contagious disease that poses a constant threat to the poultry industry around the globe. Due to the complex clinico-pathological picture and high genetic variability, the efficient diagnosis of NDV strains is a challenge. In an emerging wave of ND in the north of Pakistan, samples from six outbreaks in commercial poultry and two from healthy backyard poultry flocks were screened for NDV. A real-time PCR based on the fusion and polymerase genes of NDV detected all six isolates whereas a validated real-time PCR based on the matrix gene failed to detect any of these isolates, most likely due to substantial mismatches in the probe-binding site. All isolates have shown ICPI and MDT values similar to the velogenic form of NDV strains. The cleavage site in the F protein was found to be (112)RRQKR↓F(117), typical of virulent NDV. Phylogenetic reconstruction, based on fusion and matrix genes, provided enough evidences to consider these isolates as a new subgenotype within genotype VII. This study raised concerns about the genetic variability of NDV circulating in Pakistan, and sensitivity of the assays for the detection of the NDV isolates in clinical samples.

Human enteroviruses (HEV) are one of the major causes of central nervous system (CNS) infections in pediatrics. A prospective study was conducted to assess the epidemiological, clinical, and laboratory characteristics of enterovirus (EV) infections of the CNS in children under 15-years-old, suspected of having viral CNS infections and admitted to the Pediatric Department of Monastir University Hospital, Tunisia. Enteroviral RNA was detected by 5' NCR nested RT-PCR assay in 33 % (20 out of 60) of cerebrospinal fluid specimens, whereas only six samples (10 %) were EV positive in cell culture. EV-positive patients were clustered according to their clinical manifestations, predominantly diagnosed as aseptic meningitis (65 %) and meningoencephalitis (20 %). Fever, headache, vomiting, and neck stiffness were the most pronounced symptoms. Pleocytosis with the predominance of lymphocytes was observed in 60 % of EV positive specimens. Although patients suffering from EV infections were encountered throughout the year, most occurred during spring and summer months. Using VP1-2A nested RT-PCR and sequence analysis, three of the 20 positive HEV were identified as Echovirus (E)-9. This is the first report of a cluster of aseptic meningitis cases caused by E-9 in Monastir.

Hepatitis C is one of the foremost challenging diseases all over the world. No vaccine has been developed, yet against Hepatitis C virus (HCV). This is partly due to the high mutation rate in the HCV genome, which generates new genotypes and sub genotypes. A mass of efforts have been devoted for the development of an efficient vaccine against HCV. DNA Vaccines, an emerging field of Vaccinology, grasp strong potential to be the most reliable and efficient mode of vaccination in the future. This technology is under investigation currently. Incredibly diverse approaches have been applied as an endeavor to develop a potent DNA vaccine against HCV. The HCV structural genes and the virus like particles have been attempted and so far the results are quite promising in the Lab animals. As there is no proper animal model for HCV infection except chimpanzees, it is very difficult to articulate whether these vaccines will also be pertinent in humans or not. This review will focus on different approaches being used for the development of DNA vaccines, the major tribulations in designing a DNA vaccine against HCV as well as the future prospects for the improvement of under trials DNA vaccines developed against HCV.

Rabies in domestic and wild animals continues to be a major public health threat in India. Rapid and accurate diagnosis of rabies in animals is therefore of utmost importance as the individuals who were in contact with the rabid animals are at a greater risk. A significant amount of diagnostic tissue samples submitted to our laboratory are often autolysed and the WHO recommended direct fluorescent antibody test (FAT) for rabies diagnosis cannot be used in such samples. In this pilot study we have evaluated three different diagnostic primer sets for rapid sensitive and specific detection of rabies genome from the brain samples of different species of animals. We have validated a sensitive RT-PCR assay using brain tissue samples from different species of animals such as cat, cattle, dog, mouse and human, for routine diagnosis of rabies. Our results show the potential of this assay as a confirmatory test when the FAT results are unreliable and also as an alternative diagnostic test in circumstances when the diagnostic samples are unsuitable for use in FAT. Furthermore the nucleotide sequence of nucleoprotein gene amplified using this assay can also be used for the molecular epidemiological study of the rabies viruses in India.

In our paper we have researched the relationship between picornaviruses (poliovirus, foot-and-mouth disease virus and encephalomyocarditis virus) and Ciliata (Paramecium caudatum). We show that the number of Paramecium in medium sharply increased during coincubation with picornaviruses within 2-5 days. This cannot be explained only by the fact that viruses were nutrient source for Paramecium because in case of inactivated viruses the number of infusorians in medium increased a little. At the same time the titer of viruses harshly decreased whereas in the control group, which is free of Paramecium, the fall of titer was little. Picornaviruses were eliminated from medium if only living Parameciums were present in medium. After 7-9 days of coincubation only a few number of viruses were liberated from destroyed Parameciums. These results will be especially useful for management of reservoirs of picornaviruses in water and prevention of diseases.