Experimental evidence for competitive growth advantage of genotype VII over VI: implications for foot-and-mouth disease virus serotype A genotype turnover in nature

In India, systematic genotype replacement has been observed for serotype A foot-and-mouth disease virus. After a decade of co-circulation of genotypes VI and VII, genotype VII emerged as the single dominant genotype since 2001. To derive possible explanations for such epochal evolution dynamics, in vitro intergenotype growth competition experiments involving both co- and superinfection regimes were conducted. Coinfection of BHK-21 cells demonstrated abrupt loss in the genotype VI viral load with commensurate increase in the load of genotype VII as measured by the genotype differentiating ELISA, RT-PCR and real-time RT-PCR. The superinfection dynamics was shaped by temporal spacing of infection, where the invading genotype VII took more number of passages than coinfection to eventually overtake the resident genotype VI. It was speculated that such superior replicative fitness of genotype VII could have been a possible factor for the ultimate dominance of genotype VII in nature.     

Emergence of a novel subgroup within the widely circulating lineage of foot-and-mouth disease virus serotype Asia 1 in India

The complete VP1 encoding (1D) gene of 54 foot-and-mouth disease (FMD) virus serotype Asia1 field isolates, most of which were isolated during 2000 and 2001, was sequenced. The phylogenetic analysis identified a novel subgroup (>10% nucleotide divergence) within the widely circulating lineage of this serotype. The newly emerged viruses were responsible for disease outbreaks in both cattle and buffaloes and were present in six different states in the country. Amino acid sequence comparison of these isolates revealed significant sequence divergence at many of the amino acid positions in comparison to those of lineage VI-A and C. Emergence of such viruses may affect the efficacy of vaccine strain currently used for protection against FMD in India.     

Implications of Fungicidal Effects of Benzimidazole Compounds on Duddingtonia flagrans in Integrated Nematode Parasite Management in Livestock

An in vitro trial with carbendazim fungicide on the growth profile of the predatory fungus Duddingtonia flagrans was undertaken and in vivo trials in sheep and buffaloes, fed on chlamydospores of D. flagrans and administered albendazole anthelmintic, were conducted. Although no growth inhibition was detected at a carbendazim concentration of 0.05 ppm, growth inhibition was recorded of 50% and above at concentrations of 0.25 and 1.00 ppm (p < 0.001) and of around 90% at concentrations of 2.00 to 5.00 ppm (p <0.0001). Scanty recovery of the fungus was made from faecal culture 48 h following a single dose of albendazole both in sheep and buffaloes. However, profuse fungal recovery was made from 96 h post dosing onwards. When the drug was used as an intraruminal slow-release capsule, no faecal fungal recovery could be made from day 3 after administration of the capsule, when the albendazole sulphoxide concentration was around 1.0 microg/ml. However, profuse and scanty fungal recovery could be made on days 1 and 2, respectively, after administration of the capsule, when the plasma albendazole sulphoxide concentration was around 0.4 and 0.9 microg/ml, respectively. The implications for use of a combination of anthelmintics and biological control in sustainable parasite control programmes are discussed.     

Antigenic characterization of foot-and-mouth disease virus serotype Asia1 field isolates using polyclonal and monoclonal antibodies

Foot-and-mouth disease virus (FMDV) serotype Asia1 field isolates (n = 100) were compared using a panel of 11 monoclonal antibodies (Mab) in sandwich ELISA. The majority (over 89%) of the isolates showed either homologous (76% and above reactivity) or reduced affinity (20-75% reactivity) for the Mabs 2A, 13, 40, 34 and 81, suggesting that these Mab binding epitopes are conserved, whereas a more variable reactivity was observed for the Mabs B3, 1A, 24, 72, 82 and 89. Polyclonal relationship ('r' value) of the field isolates in liquid phase blocking (LPB) ELISA was examined, and the mean 'r' value was 0.62 relative to vaccine virus IND 63/72. Some of the field isolates (n = 34) were tested in virus neutralization test (VNT) and showed an 'r' value of >0.40. Although a minor antigenic difference was observed in the Mab profiling study, there has not been large antigenic divergence between reference virus and field viruses, thereby providing evidence of wide antigenic coverage of the vaccine strain.     

Chemotherapeutic efficacy of sulphadimidine, amprolium, halofuginone and chloroquine phosphate in experimental Eimeria bareillyi coccidiosis of buffaloes

Sulphadimidine, amprolium, halofuginone and chloroquine phosphate were administered to buffalo calves 10 days after experimental infection with Eimeria bareillyi. Animals given sulphadimidine or amprolium remained clinically normal and shed only a few oocysts in their faeces. Halofuginone was found partially effective and chloroquine phosphate completely ineffective in preventing faecal oocyst discharge and intestinal lesions. Sulphadimidine and amprolium treated calves gained weight, but chloroquine treated calves suffered progressive weight loss similar to that of infected untreated controls. No significant alterations of haematological values were observed either in the treated calves or in the untreated controls.     

Alterations in the intestinal brush border membrane structure and function in chronic DDT-exposed monkeys

Intestinal uptake of d-glucose, l-leucine, and glycine is considerably enhanced in monkeys exposed to subacute doses of DDT for 100 days. The brush border sucrase and lactase activities were also significantly elevated but there was no change in alkaline phosphatase, lactate dehydrogenase, and Mg²⁺-ATPase activities in the pesticide-administered animals compared to controls. Kinetic evidence revealed that augmentation of disaccharidases in the pesticide-treated animals is because of an increase in the enzyme content. Cholesterol and triglyceride fractions of the brush border membrane were also elevated but sialic acid content was reduced in the insecticide-treated animals compared to control group. These results suggest that observed changes in the functional activity of the enterocytes in DDT toxicity are possibly related to the alterations in the brush border membrane structural organization.     

Validation and Marker-Assisted Selection of Stem Rust Resistance Gene Sr2 in Indian Wheat Using Gel-Based and Gel-Free Methods

Journal of Crop Science and Biotechnology - Stem rust resistance gene Sr2 is an important slow-rusting gene which has provided resistance against stem rust for many years. The Sr2 gene has durable...