Indian Journal of Virology最新文献

An evaluation of 70 accessions of ash gourd germplasm grown at National Bureau of Plant Genetic Resources, New Delhi, India during Kharif season (2010) showed natural occurrence of a yellow stunt disease in three accessions (IC554690, IC036330 and Pusa Ujjwal). A set of begomovirus specific primers used in PCR gave expected amplicon from all the symptomatic plants; however no betasatellite was detected. Complete genome of the begomovirus (DNA-A and DNA-B), amplified through rolling circle amplification, was cloned and sequenced. The begomovirus under study shared high sequence identities to different isolates of Tomato leaf curl New Delhi virus (ToLCNDV) and clustered with them. Among those isolates, the DNA-A and DNA-B of the present begomovirus isolate showed highest 99.6 and 96.8 % sequence identities, respectively with an isolate reported on pumpkin from India (DNA-A: AM286433, DNA-B: AM286435). Based on the sequence analysis, the begomovirus obtained from ash gourd was considered as an isolate of ToLCNDV. Thus, the present findings constitute the first report of occurrence of a new yellow stunt disease in ash gourd from India and demonstrated the association of ToLCNDV with the symptomatic samples. Occurrence of ToLCNDV in ash gourd germplasm not only adds up a new cucurbitaceous host of this virus but also raises the concern about the perpetuation of this virus in absence of its main host tomato and thus has an epidemiological relevance for understanding the rapid spread of this virus in tomato and other hosts in Indian sub-continent.

The aim of the present study was to determine the causative agent of infected swines in the Jilin province of China and assess its genetic characteristics. Virus was isolated from tissues suspected of being infected by porcine reproductive and respiratory syndrome virus (PRRSV) and inoculated onto MARC-145 cells. Virus detection was carried out by RT-PCR, immunofluorescence, electron microscopy and sequencing. The results showed that the isolate was the North American genotype PRRSV, termed the JL-04/12 strain, with a 15,320 bp genome. The homology of the amino acid sequences in two nonstructural proteins and GP2 to GP5, between strains JL-04/12 and HUN4, ranged from 97.2 to 99.3 %. However, JL-04/12 GP6 and N protein were identical in HP-PRRSV JXA1 and HUN4. JL-04/12 was characterized by two discontinuous deletions in Nsp2. We speculate that the isolate is a variant of highly pathogenic porcine reproductive and respiratory syndrome derived from strains in 2006-2008. Altogether, these results indicate that highly pathogenic porcine reproductive and respiratory syndrome virus still exists in the Jilin province of China.

During a survey conducted in the grapevine orchards of Himachal Pradesh, variety of symptoms ranging from leaf yellowing, vein greening, reduced leaf size, downward rolling/cup shaped leaves to reduced fruit bearing were observed. Symptomatic leaf samples were collected and analyzed by serological (DAS-ELISA) and molecular methods (RT-PCR, PCR) for viruses and phytoplasma known worldwide on grapevine. DAS-ELISA was used for detection of Grapevine leafroll associated virus 1, 2 and 3 (GLRaV-1, 2 & 3), Grapevine virus A (GVA), Grapevine fan leaf virus (GFLV), Grapevine fleck virus (GFkV) and successfully detected GLRaV-1 & 3 and GFkV. All these samples were complemented with RT- PCR along with GVb and phytoplasma (additional to ELISA) using specific primers. Specific amplification in RT-PCR for GLRaV-1 (~232 bp), GLRaV-3 (~300 bp), GFkV (~179 bp) and GVB (~440 bp) confirmed the presence of these pathogens. Overall, ELISA and RT-PCR results confirmed the presence GLRaV-3 (66.7 %), GLRaV-1& GFkV (50 %), and Grapevine virus B (GVB) (12.5 %) in symptomatic plants. None of the samples were found positive for GFLV, GLRaV-2 and phytoplasma. Mixed infection was common and none of the plants were found virus free. To the best of our knowledge this is the first report of detection of GFkV and GVB in India.

Amasya is the greatest onion producing area in Turkey. Onion fields from Amasya region were surveyed for virus diseases in 2009-2011 and tested for the presence of the most important onion viruses such as Onion yellow dwarf virus (OYDV), Iris yellow spot virus (IYSV), Leek yellow stripe virus (LYSV), Shallot latent virus (SLV) and Garlic common latent virus (GCLV). The presence of virus diseases and their identification was ascertained through symptom observation in the fields, sap transmission to hosts, and DAS-ELISA. Based on the ELSA results, 57 out of 332 samples (17.16 %) were infected with viruses. The results showed that the highest infection was caused by OYDV (12.33 %) followed by LYSV (3.60 %). Only 1.19 % of the samples were infected with SLV, but none of the samples were found to be infected for GCLV and IYSV.

This study describes development of a TaqMan probe based real time PCR assay that can detect BoHV-1 of as low as 0.001 TCID50/0.1 ml in clinical samples, its comparative evaluation with indirect ELISA and virus isolation for detection of Bovine herpes virus-1 (BoHV-1) in semen and swab clinical samples. For this study, we collected samples from 212 animals (cattle and buffaloes) comprising 91 bulls and 121 females. Avidin-biotin ELISA employed on serum samples from 212 animals revealed 74 as seropositive for BoHV-1. On inoculation of semen/swabs on MDBK cell line, nine samples yielded cytopathic changes characteristic of herpes viruses. The isolates were confirmed by VNT and a conventional PCR. A real time PCR assay was standardised by designing a new set of TaqMan probe and primers targeting a 71 bp region on gB gene of the virus. The assay detected viral antigen in 21 seropositive and 14 seronegative animals, emphasizing the relevance of serology in BoHV-1 diagnosis, particularly in breeding stations. Further, real time PCR assay was 100 % sensitive and 87.19 % specific compared to virus isolation in detection of the BoHV-1 in clinical samples. The assay was validated at reputed national laboratories, with a sensitivity of ≥99 %.

The mammalian host immune system has wide array of defence mechanisms against viral infections. Depending on host immunity and the extent of viral persistence, either the host immune cells might clear/restrict the viral load and disease progression or the virus might evade host immunity by down regulating host immune effector response(s). Viral antigen processing and presentation in the host cells through major histocompatibility complex (MHC) elicit subsequent anti-viral effector T cell response(s). However, modulation of such response(s) might generate one of the important viral immune evasion strategies. Viral peptides are mostly generated by proteolytic cleavage in the cytosol of the infected host cells. CD8(+) T lymphocytes play critical role in the detection of viral infection by recognizing these peptides displayed at the plasma membrane by MHC-I molecules. The present review summarises the current knowledge on the regulation of mammalian host innate and adaptive immune components, which are operative in defence mechanisms against viral infections and the variety of strategies that viruses have evolved to escape host cell immunity. The understanding of viral immune evasion strategies is important for designing anti-viral immunotherapies.

The present study for the first time describes biological and molecular characterization of Citrus tristeza virus (CTV) occurring in the Terai area of Uttarakhand State in Northern Himalaya region of India. Direct antigen coated-ELISA and reverse transcriptase-polymerase chain reaction (RT-PCR) detected the CTV infection in Acid lime cv. Pant lemon (Citrus aurantifolia) orchards of Pantnagar with an estimated disease incidence of 16.6-20.5 %. To know the biological and genetic properties, an isolate, CTV Pant 4 was characterized. Isolate Pant 4 could be graft transmitted to Kinnow, Nagpur and Darjeeling mandarins, Mosambi sweet orange, Kagzi lime, Sweet lime, Sour orange but not to Rough lemon. The sequence analyses of the 5'ORF1a (3038 nucleotides) of LPro domain and 3'end (2058 nt) covering ORF7-ORF10 regions of the CTV genome revealed that Pant 4 was closely related to the previously reported Indian CTV isolate, Kpg3 from Northeastern Himalaya region with 97 and 98 % sequence identity, respectively. Whereas, it differed from the previously reported CTV isolate B165 from Southern India with 79 and 92 % identity, respectively for 5'ORF1a and 3' end regions. Recombination and SplitsTree decomposition analyses indicated that CTV isolate Pant 4 was a recombinant isolate originating from Kpg3 as a major and B165 as a minor donor.