Global epidemiological analysis is vital for implementing progressive regional foot-and-mouth disease control programmes. Here, we have generated VP1 region sequences for 55 Indian type A outbreak strains and have included complete VP1 sequences from 46 other countries to obtain a comprehensive global phylogeographical impression. A total of 26 regional genotypes within three continental topotypes, based on a 15 % nucleotide divergence cut-off criterion, could be identified. These genotypes correlated with distinct evolutionary lineages in the maximum-likelihood phylogeny. During the last decade, ten genotypes have been in circulation the world over and it was evident that no type A strain has transgressed the continental barriers during this period. A single genotype (genotype 18) within the Asia topotype has been circulating in India with neither any incursion nor any long distance movement of virus out of the country during the last ten years, although close genetic and epidemiological links between viruses from Bhutan and India were revealed.
Bluetongue virus serotype-1 (BTV-1) was isolated from Culicoides oxystoma vectors captured on livestock farms in two places of Gujarat, India. The viruses were isolated on BHK-21 cells, which produced characteristic BTV-related cytopathic effects between 24 and 48 h post-infection. Virus antigen was demonstrated in infected cells at different passage by a BTV-specific sandwich ELISA. Further, polyacrylamide gel electrophoresis and silver staining of viral genomic RNA revealed ten double-stranded RNA segments characteristic of BTV. Serotype of the isolates was identified by virus neutralization and PCR coupled with sequencing. The isolates were designated as SKN-7 and SKN-8 and their genome segment-2 (VP2) were sequenced. Phylogenetic analyses revealed very close relationship between them although they are not identical. SKN-8 showed closer relationship with a recently isolated BTV-1 from goat. Bluetongue virus was earlier isolated from Culicoides in adjacent state more than 20 years ago, although the serotype of the virus was not determined.
Escherichia coli O157 outbreaks were identified in Minnesota in February 2003 involving seven persons and in Colorado in July 2003 involving 13 persons. Case isolates from the two states had matching pulsed-field gel electrophoresis (PFGE) patterns. Independent case-control studies linked infections in each outbreak with eating alfalfa sprouts that were traced to the same seed distributor. The Colorado sprouter reportedly complied with the Food and Drug Administration (FDA) sprout guidance, whereas the Minnesota sprouter did not. These investigations revealed that increased compliance with existing FDA guidance is needed and that additional research is needed to improve the alfalfa seed decontamination process. This reaffirms the FDA recommendation that raw alfalfa sprouts should be considered potentially contaminated and avoided by persons at high-risk such as the elderly, young children, and immunocompromised persons. PFGE played an essential role in linking these two temporally and geographically distinct E. coli O157 outbreaks.
Eight bluetongue viruses (BTV) were isolated in BHK-21 cell culture from blood of goats suffering from peste des petits ruminants. These viruses were identified as BTV serotype 1 (BTV-1) by RT-PCR using VP2-gene-based primers coupled with sequencing of the PCR products. All of the isolates showed similar genome migration profile in 8% polyacrylamide gel electrophoresis. The genome segment-2 (seg-2) of one isolate (MKD18/India/2008) was amplified piecemeal by overlapping PCR, and the products were sequenced to obtain full-length seg-2. Phylogenetic analysis based on the seg-2 sequence revealed that MKD18 is closely related to Australian BTV-1 isolates, with 86.3-86.8% nucleotide identity. Phylogenetic analysis based on the partial sequence of seg-2 (541 bp, nucleotides 1,304-1,844) showed that the Indian BTV-1 isolates, namely, MKD18, Avikanagar, Sirsa-3 and Chennai, are very closely related to each other, with more than 99.6% nucleotide identity. Although a high degree of similarity exists, the Indian BTV-1 isolates collected over the past 25 years should be studied to demonstrate the co-existence of different VP2 antigenic profiles.
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