Vasudevan Gowthaman

Influence of Dose of Inocula on Outcome of Clinical Disease in Highly Pathogenic Avian Influenza (H5N1) Infections—An Experimental Study

Abstract Twelve-week-old Vanaraja (an Indian native dual purpose breed) chickens were inoculated intranasally with different doses (100, 1000, and 10,000 mean embryo infective dose [EID50]) of H5N1 virus, and the clinical disease and pathologic changes were compared. Although the overall severity of clinical signs was more severe in the 100 EID50 group, the progression of the clinical disease was slower with delayed onset of mortality when compared with the other two groups. The mean death time of the 100 EID50 group (4.57 days) differed significantly from that of the 10,000 EID50 group (3.60 days) and from that of the 1000 EID50 group (3.33 days). Similarly, overall severity of gross lesions was expressed more in the 100 EID50 group. The histopathologic lesions were of a more hemorrhagic and necrotic nature in the 100 EID50 group, histopathologic lesions were of an inflammatory/proliferative nature in the 1000 EID50 group, and a tendency for intravascular coagulopathy was observed in the 10,000 EID50 group. These differences may be assigned to the influence of dose in the outcome of disease.

Occurrence of Clostridium perfringens contamination in poultry feed ingredients: Isolation, identification and its antibiotic sensitivity pattern

This work has been undertaken to study the occurrence of Clostridium perfringens contamination in the poultry feed ingredients and find out its in-vitro antibiotic sensitivity pattern to various antimicrobial drugs. Two hundred and ninety-eight poultry feed ingredient samples received at Poultry Disease Diagnosis and Surveillance Laboratory, Namakkal, Tamil Nadu in South India were screened for the presence of C. perfringens. The organisms were isolated in Perfringens agar under anaerobic condition and subjected to standard biochemical tests for confirmation. In vitro antibiogram assay has been carried out to determine the sensitivity pattern of the isolates to various antimicrobial drugs. One hundred and one isolates of C. perfringens were obtained from a total of 298 poultry feed ingredient samples. Overall positivity of 33.89% could be made from the poultry feed ingredients. Highest level of C. perfringens contamination was detected in fish meal followed by bone meal, meat and bone meal and dry fish. Antibiogram assay indicated that the organisms are highly sensitive to gentamicin (100%), chlortetracycline (96.67%), gatifloxacin (93.33%), ciprofloxacin (86.67%), ofloxacin (86.67%) and lincomycin (86.67%). All the isolates were resistant to penicillin-G. Feed ingredients rich in animal proteins are the major source of C. perfringens contamination.

Detection and partial genetic characterisation of a novel variant of Avian nephritis virus in Indian poultry flocks showing diverse clinical signs.

Avian nephritis virus (ANV) infects poultry flocks worldwide, but no confirmed cases have been reported from India so far. In the current study, disease investigation was carried out in 21 broiler flocks at different parts of India with clinical signs of nephritis, uneven and stunted growth, diarrhoea, reduced body weight, and mortality up to 9.72%. Out of the 21 flocks screened, two were found positive for ANV in RT-PCR assay. BLAST analysis revealed that the ANV of Indian origin was closely related to ANV-1 strains reported from Japan, Hungary and China. However, comparison of a small portion (~12% of nucleotides, i.e. ~60 nts, common site for ANV-1 and ANV-3, position 2200-2260 of ORF 1a gene) of the Indian ANV sequence with ANV-3 sequences revealed 89-93% identities with different ANV-3 isolates. Phylogenetically, ANV-1 forms three clades, and the Indian ANV clustered under clade II. This study confirms the existence of ANV in Indian poultry flocks and is the first report on the molecular detection and genetic characterisation of ANV from India.

Molecular detection and characterization of infectious laryngotracheitis virus (Gallid herpesvirus-1) from clinical samples of commercial poultry flocks in India

Although the existence of infectious laryngotracheitis virus (ILTV) in India was first reported in 1964, no reports are available regarding its molecular detection and characterization. The present study was aimed to detect and characterize ILTV from recent respiratory disease complex (RDC) outbreaks of commercial poultry flocks in different parts of the country by using envelope glycoprotein G gene (US4 gene) based PCR and sequencing. A total of thirty two flocks with a history of RDC were investigated. Overall, all the strains/breeds of birds and all ages of birds are equally susceptible and depending on the severity, the clinical signs and gross lesions were varied. Out of 32 flocks investigated 10 were found positive for ILTV infection by PCR. The phylogenetic analyses of eight representative sequences in the present study deciphered that Indian ILT viruses are closely related to chicken embryo origin vaccine strains of Italy, USA, China and Brazil.

Isolation and phylogenetic characterization of haemagglutinin and neuraminidase genes of H9N2 low pathogenicity avian influenza virus isolated from commercial layers in India

Avian influenza is a highly infectious and dynamically evolving disease of birds causing high morbidity and mortality. It is caused by avian influenza virus (AIV) that belongs to the family Orthomyxoviridae. Two types of AIV have been described based on their pathogenicity viz. highly pathogenic avian influenza virus that causes severe disease with high mortality and low pathogenic avian influenza virus (LPAI) that generally causes asymptomatic infection or a mild disease. The H9N2 subtype is the widely circulated LPAI type in the world. The H9N2 subtype of was first reported from northern India in March 2003. However, systematical surveillance information for the evolution of H9N2 viruses in poultry flocks of Southern India is lacking. The present study reports the isolation and characterization of H9N2 isolates from the southern parts of the country during the period between May 2010 and September 2011. Out of the 30 poultry flocks investigated, six were found to be positive for HA activity. Further, all the six samples conformed as AIV. Partial nucleotide sequencing of the HA and NA genes revealed that all were belonging to the H9N2 subtype. Phylogenetically, the HA and NA genes of the H9N2 viruses from India clustered with those isolated from Bangladesh, Pakistan and the Middle East, although we were not able to conclude on their exact geographic origin.

Molecular Survey of Respiratory and Immunosuppressive Pathogens Associated with Low Pathogenic Avian Influenza H9N2 Subtype and Virulent Newcastle Disease Viruses in Commercial Chicken Flocks

The study was carried out in 48 poultry flocks to elucidate the roles of various complicating pathogens involved along with Newcastle disease (ND)/ low pathogenic avian influenza (LPAI) outbreaks. Necropsy was conducted and samples were collected for the isolation of Newcastle disease virus (NDV), Influenza A virus, infectious bronchitis virus (IBV), pathogenic bacteria; molecular detection of infectious laryngotracheitis virus (ILTV), fowl adeno virus (FAV), chicken anaemia virus (CAV), Mycoplasma synoviae (MS) and Mycoplasma gallisepticum (MG). The isolation results confirmed that 18/48 flocks (37%) were positive for the presence of hemagglutinating agents. Out of 18 hemagglutination (HA) positive flocks, 11 flocks (61%) were positive for both avian influenza virus (AIV) and NDV; 4 flocks (22%) were positive for NDV; and 3 flocks (17%) were positive for AIV. Sequence analysis of hemagglutinin and neuraminidase genes of AIV revealed that all were belonging to LPAI-H9N2 subtype. Sequence analysis of F gene of NDV revealed that they belong to virulent type. The PCR results confirmed the presence of three to seven etiological agents (CAV, FAV, ILTV, MG, MS and avian pathogenic E. coli along with LPAI/NDV from all the 18 HA-positive flocks. The detection rate of triple, quadruple, quintuple, sextuple and sevenfold infections was 17% (3 flocks), 28% (5 flocks), 11%, (2 flocks) 28% (5 flocks) and 17% (3 flocks), respectively. In conclusion, the disease complex involved more than one pathogen, primarily resulting from the interplay between LPAI-H9N2 and NDV; subsequently this could be exacerbated by co-infection with other agents which may cause exacerbated outbreaks that may otherwise go undetected in field.

Detection of Sub Clinical Infection of Mycoplasma gallisepticum in Commercial Chicken by Indirect ELISA

| Chronic Respiratory disease in Poultry is mainly caused by Mycoplasma gallisepticum (MG). It causes huge economic loss to the poultry industry. The present research work has been undertaken to know the sero-prevalence of MG in commercial layers in Namakkal region of Tamil Nadu, India. A total of 103 commercial layer sera samples from 6 commercial layer farms were subjected to indirect ELISA. From 103 sera samples, overall prevalence found 53.40% for commercial layer chickens. The highest (100%) sero-prevalence of MG was recorded at 32 weeks and the lowest (0%) was recorded at 68 weeks of commercial layer chicken. This study demonstrated high sero-prevalence of MG in Commercial Layers. Therefore, routine monitoring of the commercial layer farms for MG infection should be recommended and mycoplasma control programmes must be strictly adhered.

Spontaneous Occurrence of Oviduct Infundibular Adenocarcinoma in a Layer Chicken

The present communication reports a spontaneous case of non-viral, metastatic infundibular adenocarcinoma in a 74 week old commercial layer chicken. On necropsy examination, mesentery, serosal surface of intestine and pancreas were studded with 5 mm grayish white nodules. Fimbrial region of oviduct contained varying sizes of multiple single to lobulated grayish white nodules. Serosal surface of tubular neck region showed tiny pearl-like nodules and the mucosal surface was diffusely thickened. Microscopically, cuboidal neoplastic cells were arranged in acinar and tubular pattern in the serosal layer of infundibulum. The cells appeared as variable sized cuboidal cells with indistinct cell borders, eosinophilic granular cytoplasm, round nuclei, indistinct nucleoli and fine chromatin granules. Transcoelomic nodules showed neoplastic cells and structures similar to those of the oviductaltumor.

An outbreak of pulmonary aspergillosis in emu (Dromaius novaehollandiae) chicks

Pulmonary aspergillosis in 5 week old emu chicks with 60 and 53.33 per cent of morbidity and mortality was reported. On gross examination, numerous small greyish yellow nodules were seen on the lungs and air sacs. Microscopically a granulomatous inflammatory reaction associated with fungal hyphae was observed in lung parenchyma and air sacs. The gross and microscopic lesions, in combination with the mycological identification provided the diagnosis of pulmonary aspergillosis due to A. fumigatus. Contaminated litter was identified as a source of infection. The disease was controlled by removal of primary source of infection and treating the affected birds with copper sulphate through drinking water.