Department of Veterinary Medicine

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Author: search.filters.author.Subbiah, Madhuri

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    Experimental infection of hamsters with avian paramyxovirus serotypes 1 to 9
    (Springer Nature, 2011-02-23) Samuel, Arthur S; Subbiah, Madhuri; Shive, Heather; Collins, Peter L; Samal, Siba K
    Avian paramyxoviruses (APMVs) are frequently isolated from domestic and wild birds throughout the world and are separated into nine serotypes (APMV-1 to -9). Only in the case of APMV-1, the infection of non-avian species has been investigated. The APMVs presently are being considered as human vaccine vectors. In this study, we evaluated the replication and pathogenicity of all nine APMV serotypes in hamsters. The hamsters were inoculated intranasally with each virus and monitored for clinical disease, pathology, histopathology, virus replication, and seroconversion. On the basis of one or more of these criteria, each of the APMV serotypes was found to replicate in hamsters. The APMVs produced mild or inapparent clinical signs in hamsters except for APMV-9, which produced moderate disease. Gross lesions were observed over the pulmonary surface of hamsters infected with APMV-2 & -3, which showed petechial and ecchymotic hemorrhages, respectively. Replication of all of the APMVs except APMV-5 was confirmed in the nasal turbinates and lungs, indicating a tropism for the respiratory tract. Histologically, the infection resulted in lung lesions consistent with bronchointerstitial pneumonia of varying severity and nasal turbinates with blunting or loss of cilia of the epithelium lining the nasal septa. The majority of APMV-infected hamsters exhibited transient histological lesions that self resolved by 14 days post infection (dpi). All of the hamsters infected with the APMVs produced serotype-specific HI or neutralizing antibodies, confirming virus replication. Taken together, these results demonstrate that all nine known APMV serotypes are capable of replicating in hamsters with minimal disease and pathology.
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    Genetics of Avian Paramyxovirus serotype 2
    (2010) Subbiah, Madhuri; Samal, Siba K.; Veterinary Medical Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Avian Paramyxovirus (APMV) serotype 2 is one of the nine serotypes of APMV that infect a variety of bird species around the world. In chickens and turkeys, APMV-2 causes respiratory illness and drop in egg production. To understand the molecular characteristics of APMV-2, the complete genome sequences of prototype strain Yucaipa and strains Bangor, England and Kenya were determined. The genome lengths of APMV-2 strains Yucaipa, Bangor, England and Kenya are 14904, 15024, 14904, 14916 nucleotides (nt), respectively. Each genome consists of six non-overlapping genes in the order 3'N-P/V/W-M-F-HN-L5' similar to most of APMVs. Sequence comparison of APMV-2 strains England and Kenya with prototype strain Yucaipa show 94-98% nt and 90-100% aggregate amino acid (aa) identities. However, strain Bangor shares low level of nt and predicted aa sequence identities with the other three strains. The phylogenetic and serological analyses of all four strains indicated the existence of two subgroups: strains Yucaipa, England and Kenya represented one subgroup and strain Bangor represented the other subgroup. All four strains were found to be avirulent for chickens by mean death time and intracerebral pathogenicity test. To further study the molecular biology and pathogenicity of APMV-2, a reverse genetics system for strain Yucaipa was established in which infectious recombinant APMV-2 was recovered from a cloned APMV-2 antigenomic cDNA. The recovered recombinant virus showed in vitro growth characteristics and in vivo pathogenicity similar to wild type virus. Recombinant APMV-2 expressing enhanced green fluorescent protein was also recovered, suggesting its potential use as a vaccine vector. Furthermore, generation and characterization of mutant viruses by replacing the fusion protein (F) cleavage site of APMV-2 with those of APMV serotypes 1 to 9 demonstrated that the amino acid composition at F protein cleavage site does not affect the pathogenicity of APMV-2. Overall, the study conducted here has several downstream applications. The complete genome sequence of APMV-2 is useful in designing diagnostic reagents and in epidemiological studies. The reverse genetics system for APMV-2 would be of considerable utility for introducing defined mutations into the genome of this virus and develop vaccine vector for animal and human pathogens.