Contribution to the taxonomy of the turkey coryza agent: cellular fatty acid analysis of the bacterium

Gas-liquid chromatography was used to analyze bacterial cellular fatty acids to elucidate the relatedness of the turkey coryza (TC) bacterium to Alcaligenes spp., Bordetella spp., and other gram-negative bacteria. The results indicated that the TC bacterium is not closely related to Alcaligenes faecalis or any of the reference strains of Alcaligenes and Bordetella studied. Most urease-positive bacterial isolates obtained from the upper respiratory tract of turkeys were identified as Bordetella bronchiseptica. It is suggested that Bordetella avium is a suitable designation for the TC bacterium formally called Bordetella-"like" and A. faecalis type I. It is also suggested that the nonpathogenic bacterium previously identified as type II A. faecalis be designated B. avium-like until further taxonomic studies are available. Furthermore, it is proposed that the term turkey coryza be used to refer to the disease induced by this bacterium.     

Avian influenza virus

Avian influenza viruses do not typically replicate efficiently in humans, indicating direct transmission of avian influenza virus to humans is unlikely. However, since 1997, several cases of human infections with different subtypes (H5N1, H7N7, and H9N2) of avian influenza viruses have been identified and raised the pandemic potential of avian influenza virus in humans. Although circumstantial evidence of human to human transmission exists, the novel avian-origin influenza viruses isolated from humans lack the ability to transmit efficiently from person-to-person. However, the on-going human infection with avian-origin H5N1 viruses increases the likelihood of the generation of human-adapted avian influenza virus with pandemic potential. Thus, a better understanding of the biological and genetic basis of host restriction of influenza viruses is a critical factor in determining whether the introduction of a novel influenza virus into the human population will result in a pandemic. In this article, we review current knowledge of type A influenza virus in which all avian influenza viruses are categorized.     

Molecular characterization of the capsid gene of two serotypes of turkey astroviruses

Astrovirus infections mainly cause acute gastroenteritis in children and young animals. Human astroviruses are well characterized antigenically and genetically. However, information on turkey astroviruses is limited. We isolated two astroviruses (TAstV1987 and TAstV2001) from turkeys and classified them as two different serotypes using a virus neutralization test. To elucidate the differences between these two isolates at the molecular level, further genetic characterization and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis were carried out. The sequences of the complete capsid protein gene of these two isolates were obtained by cloning and sequencing. The percentage nucleotide and predicted amino acid identities for these two sequences along with those of 16 other capsid protein gene sequences from human and animal astroviruses retrieved from GenBank were calculated using MegAlign. The results showed that TAstV1987 and TAstV2001 had 73.3% nucleotide and 82.8% amino acid identities, respectively. An unrooted Neighbor-joining phylogenetic tree of these sequences was generated using MEGA 3 software with 1000 bootstrap replicates. The results of evolutionary analysis showed that TAstV1987 was closely related genetically to another virus, designated TAstV-2, whereas TAstV2001 was not as close to TAstV-2 as TAstV1987. The analysis of the capsid proteins of the two viruses by SDS-PAGE revealed that they had different band patterns, indicating that their capsid proteins consisted of different viral proteins. The findings in this study revealed the molecular differences in the capsid protein gene of TAstV1987 and TAstV2001, which may provide the molecular basis of the antigenic differences between these two serotypes of turkey astroviruses.     

Genetic Structure of Field Populations of Begomoviruses and of Their Vector Bemisia tabaci in Pakistan

ABSTRACT The genetic structure of field populations of begomoviruses and their whitefly vector Bemisia tabaci in Pakistan was analyzed. Begomoviruses and B. tabaci populations were sampled from different crops and weeds in different locations in Punjab and Sindh provinces, in areas where cotton leaf curl disease (CLCuD) occurs or does not occur. Phylogenetic analysis based on nucleotide sequences of the intergenic region in the viral DNA-A provided evidence of two clusters of isolates: viruses isolated from species in the family Malvaceae, and viruses isolated from other dicotyledon families. Analysis of the capsid protein (CP) open reading frame grouped isolates into three geographical clusters, corresponding to isolates collected in Punjab, Sindh, or both provinces. Random amplified polymorphic DNA analyses of the B. tabaci population showed that intrapopulation diversity was high at both the local and regional scales. Sequence analysis of the mitocondrial cytochrome oxydase I (mt COI) gene showed that the B. tabaci population was structured into at least three genetic lineages corresponding to the previously described Indian, Southeast Asian, and Mediterranean-African clades. The Indian clade was present only in Punjab, the Mediterranean-African only in Sindh, and the Southeast Asian in both provinces. B. tabaci haplotypes of the Indian clade were found only in the Punjab, where CLCuD occurs. Hence, the geographical distribution of virus and vector genotypes may be correlated, because similar phylogenetic relationships were detected for the viral CP and the vector mt COI genes.     

Lack of antigenic relationships between avian pneumovirus and four avian paramyxoviruses

Avian paramyxoviruses (PMVs) and avian pneumovirus (APV) belong to the family Paramyxoviridae. Antigenic relationships between PMVs were shown previously, hence, this study was designed to investigate possible antigenic relationships between APV and four avian PMVs (PMV-1, PMV-2, PMV-3, and PMV-7). Enzyme-linked immunosorbent assay (ELISA), hemagglutination inhibition (HI) test, and virus neutralization (VN) test in chicken embryos and in Vero cells were used. The HI test was performed with the PMVs as antigens against the APV and PMVs antisera. The ELISA and VN test in chicken embryos were performed with PMVs and APV antigens and antisera. The VN test in vero cells was performed with the APV as an antigen against the PMV antisera. All the viruses were isolated in the United States or Canada. No antigenic relationships between APV and the PMVs were detected by the described tests.     

Pathogenicity of embryo-adapted serotype 2 OH strain of infectious bursal disease virus in chickens and turkeys

The pathogenicity of serotype 2 OH strain of infectious bursal disease virus (IBDV) to specific-pathogen-free (SPF) chicken embryos and 2-wk-old SPF chickens and turkey poults was investigated. The virus was pathogenic for chicken embryos after five passages as evidenced by pathologic changes in inoculated embryos. The embryo-adapted virus was not pathogenic for 2-wk-old SPF chickens and turkey poults as indicated by lack of clinical signs, gross or microscopic lesions in the bursa of Fabricius of inoculated birds. Bursa-to-body-weight ratios of the inoculated chickens and turkey poults were not significantly different from those of uninoculated controls. Virus-neutralizing antibodies to serotype 2 IBDV were detected in inoculated chickens and turkeys. Results of this study indicated that the embryo-adapted serotype 2 OH IBDV isolate that is pathogenic for chicken embryos is infectious but not pathogenic in chickens and turkeys.     

Concurrent porcine rotaviral and transmissible gastroenteritis viral infections in a three-day-old conventional pig.

A 3-day-old suckling pig with diarrhea was necropsied, and immunofluorescent microscopic examination of the small intestinal mucosa, together with immune electron microscopic examination of the large intestinal contents, provided a presumptive diagnosis of a concurrent infection with transmissible gastroenteritis (TGE) virus and porcine rotavirus. Immunofluorescent microscopic, immune electron microscopic, and serologic data obtained from gnotobiotic pigs experimentally inoculated with the large intestinal contents of the suckling pig confirmed this diagnosis. Two gnotobiotic pigs, convalescent from previous TGE viral infections, became infected with porcine rotavirus only. However, another gnotobiotic pig, convalescent from a previous porcine rotaviral infection, became infected with TGE virus only, following inoculation with the large intestinal contents of the suckling pig.     

Influence of probiotic Lactobacilli colonization on neonatal B cell responses in a gnotobiotic pig model of human rotavirus infection and disease

The goal of this study was to define the impact of colonization of gnotobiotic (Gn) pigs with lactic acid bacteria (LAB) on development of intestinal and systemic B cell responses to human rotavirus (HRV). The LAB-specific and total B cell responses were also assessed. Gn pigs were inoculated with LAB (Lactobacillus acidophilus and L. reuteri) and virulent Wa strain HRV (LAB+HRV+), HRV only (LAB-HRV+), LAB only (LAB+HRV-) or mock (LAB-HRV-). The HRV infection induced similar HRV-specific intestinal and systemic antibody and B cell responses in pigs with or without LAB, whereas LAB significantly enhanced total intestinal IgA secreting cell responses and total serum IgM and intestinal IgM and IgG titers. The LAB colonization did not reduce HRV shedding or diarrhea, this may be partly due to the short time interval between the first LAB feeding and HRV inoculation. Further studies are needed with longer time for LAB to establish before HRV inoculation. However, our studies demonstrate that Gn pigs infected with HRV develop a similar magnitude of virus-specific B cell responses as those of HRV-infected and LAB colonized pigs. LAB colonization alone is not as efficient in promoting intestinal B cell responses, as is HRV infection.