Klebsiella pneumoniae is an important emerging pathogen of humans and animals leading to serious clinical consequences. Increased antibiotic use has promoted the emergence of carbapenem-resistant and extended-spectrum β-lactamase (ESBL)-producing K. pneumoniae strains. Recently, phage therapy has gained momentum as a possible alternative against emerging antimicrobial resistance. This study was performed to assess the therapeutic effects of a novel lytic phage (VTCCBPA43) in a pneumonic mouse model in order to explore the efficacy of phage therapy against virulent K. pneumoniae infection.The tailed phage VTCCBPA43 was assessed for its growth kinetics, in vitro host range, and temperature and pH sensitivity. Protein constituents were analysed by SDS-PAGE and nLC-MS/MS. Therapeutic efficacy was observed 2 h post-challenge with virulent K. pneumoniae in a BALB/c mouse model.Phage VTCCBPA43 was found to be highly temperature-tolerant (up to 80 °C). It was most active at pH 5, had a burst size of 172 PFU/mL and exhibited a narrow host range. It was identified as a KP36-like phage by shotgun proteomics. Following intranasal application of a single dose (2 × 109 PFU/mouse) post-challenge with virulent K. pneumoniae, the presence of biologically active phage in vivo and a significant reduction in the lung bacterial load at all time points was observed. A reduction in lesion severity suggested overall beneficial effects of VTCCBPA43 phage therapy in the pneumonic mouse model.This research represents the first in vivo evidence of effective phage therapy against K. pneumoniae infection by the intranasal route.
A bacteriophage (VTCCBPA6) against a pathogenic strain of Aeromonas hydrophila was isolated from the sewage of an organized equine breeding farm. On the basis of TEM analysis, phage belonged to family Myoviridae. PCR amplification and sequence analysis of gp 23 gene (encoding for major capsid protein) revealed phylogenetic resemblance to T4 like virus genus. Protein profiling by SDS‐PAGE also indicated its resemblance to T4 like phage group. However, the comparison of its gp 23 gene sequence with previously reported phages showed similarity with T4‐like phages infecting Enterobacteriaceae instead of Aeromonas spp. Thus, to our knowledge, this report points toward the fact that a novel/evolved phage might exist in equine environment against A. hydrophila , which can be potentially used as a biocontrol agent.
Equine influenza (EI) is a highly contagious viral respiratory disease caused by the equine influenza virus (EIV). Frequent antigenic changes of EIV warrants thorough pathological evaluation and in-vivo replication of the circulating viruses in an experimental animal model for selection of vaccine strain. In the present study, EIV (H3N8) was inoculated into BALB/c mice and subsequently, gross, histopathological and immunohistochemical examination of the lungs was performed to evaluate the correlation of virus replication with corresponding pathological changes. Microscopically, at 1dpi, lungs from mice infected with EIV revealed degeneration of epithelial tissues, whereas indirect immunoperoxidase staining (IIPT) results showed high EIV antigen positivity in the bronchial and bronchiolar epithelium and mild positivity in the infiltrating cells. Subsequently from 1 dpi to 3 dpi, the virus replicated and infected other parenchymal cells, which led to recruitment of inflammatory cells. Microscopically moderate peribronchial, peribronchiolar and perivascular cuffing of neutrophils and macrophages were observed, whereas IIPT exhibited, scanty and moderate EIV antigen positive interstitial infiltrating macrophages. At 5 and 7 dpi, severe, diffuse interstitial thickening, bronchial, bronchiolar and alveolar epithelial necrosis and denudation, perivascular and peribronchial mononuclear cells cuffing were observed, which could be correlated with IIPT as high EIV antigen positivity of infiltrating macrophages and type II pneumocytes. However, from 11 dpi onwards, microscopically, moderate interstitium thickening and perivascular and peribronchial cuffing were observed whereas, tissues were negative for EIV antigen in IIPT. Mild, focal inflammation could be observed at 14 dpi. Present findings signify the correlation of virus replication with corresponding histopathological changes, which will be useful for assessing the efficacy of anti-influenza drug molecules and EIV vaccines.
Bordetella bronchiseptica is a well-known Gram-negative bacterial pathogen causing a plethora of diseases in different animals. Although its infection has been reported from pigs and dogs in India, no report of B. bronchiseptica from horses is described. We report for the first time, isolation, identification and characterization of strains of B. bronchiseptica from respiratory infection in horses from different states in India. The antimicrobial susceptibility testing showed resistance to penicillins, ceftazidime, and chloramphanicol. The virulence capability of the strains was confirmed by sequencing genes such as adenylate cyclase toxin (cyaA), bordetella virulence gene (bvgA) and by PCR detection of flagellin gene (fla). We demonstrate the involvement of B. bronchiseptica strains in respiratory tract infection in horses in India.
Background: Equine herpesvirus type 1 (EHV-1) is the most important viral pathogen of equines, causing respiratory illness, abortion, neonatal foal mortality and neurologic disorders. Large numbers of commercial EHV-1 vaccines are available to protect equines from the disease, but they provide only partial protection. Despite immunization with inactivated and modified live virus vaccine, mares show abortions. Present study was aimed to investigate the immunogenicity and protective efficacy of EHV-1 recombinant glycoprotein B (rgB) and gB expressing plasmid DNA against EHV-1 infection in BALB/c mice model.Methods: About 3-4 weeks old 225 female BALB/c mice were selected for the comparative study of immunization followed by challenged with EHV-1/India/Tohana/96-2 strain virus in 5 different groups of 45 animals each.Result: Following immunization, rgB vaccinated mice showed optimal stimulation of EHV-1 gB specific cell mediated and humoral mediated immunity (HMI and CMI). The gB expressing plasmid DNA vaccinated mice developed only CMI while inactivated whole virus vaccinated mice had only HMI. Upon EHV-1 challenge, all infected mice displayed variable levels of clinical signs with changes in body weight, however, vaccinated mice showed very rapid recovery with optimal protection. Positive control group mice showed severe pulmonary lesions along with persistence virus infection till 5 days post challenge (dpc) whereas vaccinated mice had less pulmonary lesion only up to 3dpc. Minimal lung lesions and early virus clearance was observed in the rgB immunized mice in comparison to the gB plasmid DNA and inactivated EHV-1 vaccine immunized mice. It has been concluded that immunization with rgB elicits optimum protective immune response against EHV-1 infection in mice model. The rgB could be a potential vaccine candidate against EHV-1 infection in equine in the future.
To assess the immunogenic potential of inactivated equine herpesvirus–1 (EHV–1) vaccine in murine model, female BALB/c mice (group 1) were vaccinated intraperitoneally twice, 21 days apart, while group 2 mice were sham-inoculated and served as control. After immunization, antibodies against EHV–1 were detected on day 14, 21 and 28 day by virus neutralization test and enzyme-linked immunosorbent assay, but there was no significant increase in cell-mediated immune response. After mating and confirming pregnancy, the mice were challenged by intranasal instillation of 107.0 TCID50/25 μl of EHV–1 virus (Raj–98 strain) at day 14 of gestation. Following challenge, clinical signs, viz. dyspnoea, crouching in corners, vaginal discharge, abortion, and mortality increased significantly in non-vaccinated (group 2) mice with a clinical score of 8.17 as compared to vaccinated mice, where dyspnoea, crouching in corners and mortality were not observed and clinical score was 2.0 on day 3 post-challlenge. After challenge, vaccinated mice showed less number (30%) of abortions as compared to 66.66% in non-vaccinated mice. Reduced virus titre recovery and score for herpesvirus-specific pathology in maternal lungs were observed in vaccinated dams. Indirect immunoperoxidase staining of lung tissues of immunized dam demonstrated less viral antigen than in unimmunized dams. These results confirm that inactivated EHV–1 vaccine afforded good humoral immune response and partial protection in pregnant BALB/c mice.
Equine influenza is a contagious viral disease that affects all members of the family Equidae, i.e., horses, donkeys and mules. The authors describe the pattern of equine influenza outbreaks in a number of states of India from July 2008 to June 2009. The disease was first reported in June 2008 in Katra (Jammu and Kashmir) and spread to ten other states within a year. All outbreaks of equine influenza in the various states were confirmed by laboratory investigations (virus isolation and/or serological confirmation based on haemagglutination inhibition [HI] assays of paired samples) before declaring them as equine influenza virus-affected state(s). The virus (H3N8) was reported from various locations in the country including Katra, Mysore (Karnataka), Ahmedabad (Gujarat), Gopeshwar and Uttarkashi (Uttarakhand) and was isolated in 9- to 11-day-old embryonated chicken eggs. The virus was confirmed as H3N8 by HI assays with standard serum and amplification of full-length haemagglutinin and neuraminidase genes by reverse transcriptase-polymerase chain reaction. Serum samples (n = 4 740) of equines from 13 states in India screened by HI revealed 1074 (22.65%) samples as being positive for antibodies to equine influenza virus (H3N8).
The buffalopox virus (BPXV) has emerged as an occupational zoonotic disease in the country. Host-range genes play a critical role in the host tropism of poxviruses as in the case of vaccinia viruses (VACV). Among hostrange genes, the K1L gene is required for viral replication by antagonising host-imposed interferon resistance. This study was undertaken for genetic characterisation of this VACV homologue host-range gene of BPXV isolates from buffaloes (BPXV/buffalo/Jalgaon/2010) and humans (BPXV/human/Jalgaon/2010) from an outbreak (2010) in Maharashtra. Furthermore, we also analysed the phylogenetic relationship of BPXVs with other Orthopoxviruses (OPXVs) to determine the nature of this gene within the genus. Sequence analysis revealed ORFs of 855 bp. Current isolates shared maximum homology (~99%) at both nt and aa levels with VACV. There was no sequence variation in this gene with respect to buffalo and human isolates of BPXV; however, a significant point mutation (D249N) was observed in the BPXV isolates as compared with VACV and other VACV-like viruses. Phylogenetic analysis revealed clustering of BPXV isolates with VACVs along with the vaccine strains. The close homology between BPXV and VACV suggests their similar roles in viral pathogenesis.This analysis could provide an avenue for discovering critical innate antiviral responses for the development of vaccine and antiviral agents required in the context of reduction of cohort immunity against poxviruses in the human population. This is the first report of genetic analysis of the K1L gene of the buffalopox virus.
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