scholarly journals Bluetongue virus in a Nigerian dairy cattle herd: 1. Serological studies and correlation of virus activity to vector population

1983 ◽  
Vol 90 (2) ◽  
pp. 177-193 ◽  
Author(s):  
K. A. J. Herniman ◽  
J. P. T. Boorman ◽  
W. P. Taylor
Keyword(s):  
Bluetongue Virus ◽  
Light Trap ◽  
Survival Rates ◽  
Virus Transmission ◽  
Neutralizing Antibody ◽  
Decay Rates ◽  
Vector Population ◽  
Virus Activity ◽  
Serological Studies ◽  
Trap Catches

SUMMARYNewborn calves were bled at monthly intervals and examined for serum antibodies to bluetongue virus (BTV). Maternal immunity persisted for 3 months and it was possible to calculate decay rates for virus neutralizing antibody. Calves were subclinically infected with BTV within a few months of becoming susceptible and neutralization tests were used to deduce the serotype responsible. A profile of virus activity was built up over a 12 month period. Frequent light trap catches were used to examine the population dynamics of suspected Culicoides vector species. Two species, imicola and schultzei were present throughout the wet and dry seasons and survival rates were sufficiently long to account for virus transmission at any time of the year.

scholarly journals The epidemiology of bluetongue in Malawi

1988 ◽  
Vol 100 (3) ◽  
pp. 493-499 ◽  
Author(s):  
J. M. Haresnape ◽  
W. P. Taylor ◽  
S. A. M. Lungu
Keyword(s):  
Central Region ◽  
Rainy Season ◽  
Bluetongue Virus ◽  
Neutralizing Antibody ◽  
Dry Season ◽  
Virus Activity

SummaryA 4 year survey was undertaken in 1982–6 to examine the seasonal nature of bluetongue virus activity in Malawi. Bluetongue infection at Bwemba in Lilongwe district and Likasi in Mchinji district, both in the Central Region of Malawi, was detected by examining sera taken from calves at each site, at monthly intervals. The proportion of seronegative calves undergoing serocon version each month was used as a measure of virus activity. At both sides bluetongue virus activity was found to be most marked during the rainy season, with no activity detected during the dry season from July to September. Thus the pattern of bluetongue infection in Malawi is highly seasonal. Examination of type-specific neutralizing antibody showed that the prevalent serotypes varied from year to year.

Adult lifespan and reproductive status of Culicoides species (Diptera: Cerato-pogonidae) in Kenya, with reference to virus transmission

1977 ◽  
Vol 67 (2) ◽  
pp. 205-215 ◽  
Author(s):  
Alan R. Walker
Keyword(s):  
Bluetongue Virus ◽  
Overlapping Generations ◽  
Graphical Model ◽  
Virus Disease ◽  
Survival Rates ◽  
Age Groups ◽  
Virus Transmission ◽  
Culicoides Species ◽  
Light Traps ◽  
Adult Lifespan

AbstractLight-traps were used to sample populations of C. comutus De Meillon, C. pallidipennis G, I. & M. and C. schultzei (End.) gp. at sites at Embakasi, Kiboko and Makindu between 1971 and 1975. The samples were graded into age-groups by the degree of abdominal pigmentation, estimates of calendar ageing were made, and the seasonal variation in age-structure of the populations was recorded. Survival rates were calculated on the basis of a graphical model of the continually overlapping generations, and the survival rate of 0·8 was found typical. This rate is considered sufficiently high for C. cornutus, C. pallidipennis and C. schultzei gp. to act as vectors of bluetongue virus disease of sheep and/or ephemeral fever virus disease of cattle.

scholarly journals Bluetongue in the Sultanate of Oman, a preliminary epidemiological study

1991 ◽  
Vol 107 (1) ◽  
pp. 87-97 ◽  
Author(s):  
W. P. Taylor ◽  
S. M. Al Busaidy ◽  
P. S. Mellor
Keyword(s):  
Epidemiological Study ◽  
Bluetongue Virus ◽  
Hot Spot ◽  
Neutralizing Antibody ◽  
Sultanate Of Oman ◽  
Agar Gel ◽  
Widespread Distribution ◽  
Previous Evidence ◽  
Immunodiffusion Test ◽  
Virus Activity

SUMMARYA group specific agar-gel immunodiffusion test was used to demonstrate that there is a frequent and widespread distribution of bluetongue virus throughout the Sultanate of Oman. The Culicoides midges C. imicola and C. schultzei, both capable of transmitting bluetongue group viruses, were recorded throughout the year. Although these studies did not establish that bluetongue is enzootic in Oman, type-specific neutralizing antibody results supported previous evidence for the existence of a Saudi Arabian bluetongue ecosystem. Variations in antibody evidence of virus activity within a restricted locality suggested a hot-spot theory concerning the perpetuation of the virus.

scholarly journals Simulation of leaf curl disease dynamics in chili for strategic management options

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Buddhadeb Roy ◽  
Shailja Dubey ◽  
Amalendu Ghosh ◽  
Shalu Misra Shukla ◽  
Bikash Mandal ◽  
...  
Keyword(s):  
Disease Risk ◽  
Virus Transmission ◽  
Host Population ◽  
High Rate ◽  
Disease Dynamics ◽  
Model Framework ◽  
Management Options ◽  
Transmission Parameters ◽  
Vector Population ◽  
Leaf Curl

AbstractLeaf curl, a whitefly-borne begomovirus disease, is the cause of frequent epidemic in chili. In the present study, transmission parameters involved in tripartite interaction are estimated to simulate disease dynamics in a population dynamics model framework. Epidemic is characterized by a rapid conversion rate of healthy host population into infectious type. Infection rate as basic reproduction number, R0 = 13.54, has indicated a high rate of virus transmission. Equilibrium population of infectious host and viruliferous vector are observed to be sensitive to the immigration parameter. A small increase in immigration rate of viruliferous vector increased the population of both infectious host and viruliferous vector. Migrant viruliferous vectors, acquisition, and transmission rates as major parameters in the model indicate leaf curl epidemic is predominantly a vector -mediated process. Based on underlying principles of temperature influence on vector population abundance and transmission parameters, spatio-temporal pattern of disease risk predicted is noted to correspond with leaf curl distribution pattern in India. Temperature in the range of 15–35 °C plays an important role in epidemic as both vector population and virus transmission are influenced by temperature. Assessment of leaf curl dynamics would be a useful guide to crop planning and evolution of efficient management strategies.

scholarly journals Analysis and phylogenetic comparisons of full-length VP2 genes of the 24 bluetongue virus serotypes

2007 ◽  
Vol 88 (2) ◽  
pp. 621-630 ◽  
Author(s):  
S. Maan ◽  
N. S. Maan ◽  
A. R. Samuel ◽  
S. Rao ◽  
H. Attoui ◽  
...  
Keyword(s):  
Bluetongue Virus ◽  
Neutralizing Antibodies ◽  
Neutralizing Antibody ◽  
Full Length ◽  
Molecular Diagnostic ◽  
Mammalian Host ◽  
Reading Frame ◽  
Diagnostic Assays ◽  
Primary Determinant ◽  
Serotype Identification

The outer capsid protein VP2 of Bluetongue virus (BTV) is a target for the protective immune response generated by the mammalian host. VP2 contains the majority of epitopes that are recognized by neutralizing antibodies and is therefore also the primary determinant of BTV serotype. Full-length cDNA copies of genome segment 2 (Seg-2, which encodes VP2) from the reference strains of each of the 24 BTV serotypes were synthesized, cloned and sequenced. This represents the first complete set of full-length BTV VP2 genes (from the 24 serotypes) that has been analysed. Each Seg-2 has a single open reading frame, with short inverted repeats adjacent to conserved terminal hexanucleotide sequences. These data demonstrated overall inter-serotype variations in Seg-2 of 29 % (BTV-8 and BTV-18) to 59 % (BTV-16 and BTV-22), while the deduced amino acid sequence of VP2 varied from 22.4 % (BTV-4 and BTV-20) to 73 % (BTV-6 and BTV-22). Ten distinct Seg-2 lineages (nucleotypes) were detected, with greatest sequence similarities between those serotypes that had previously been reported as serologically ‘related’. Fewer similarities were observed between different serotypes in regions of VP2 that have been reported as antigenically important, suggesting that they may play a role in the neutralizing antibody response. The data presented form an initial basis for BTV serotype identification by sequence analyses and comparison of Seg-2, and for development of molecular diagnostic assays for individual BTV serotypes (by RT-PCR).

scholarly journals Light trap catches of blackflies in southern part of Kyushu, Japan

1978 ◽  
Vol 29 (2) ◽  
pp. 107-115
Author(s):  
Hiroyuki TAKAOKA ◽  
Sinichi NODA ◽  
Susumu YAMAMOTO
Keyword(s):  
Light Trap ◽  
Trap Catches

Southern Potato Wireworms: Light-Trap Catches of Adults in an Isolated Agricultural Area123

1973 ◽  
Vol 66 (3) ◽  
pp. 757-760 ◽  
Author(s):  
Augustine Day ◽  
J. M. Stanley ◽  
J. C. Webb ◽  
J. G. Hartsock
Keyword(s):  
Light Trap ◽  
Trap Catches

scholarly journals Quantal and graded dose-responses of bluetongue virus: a comparison of their sensitivity as assay methods for neutralizing antibody

1966 ◽  
Vol 64 (2) ◽  
pp. 231-244 ◽  
Author(s):  
Sven-Eric Svehag
Keyword(s):  
Poisson Distribution ◽  
Bluetongue Virus ◽  
Neutralizing Antibody ◽  
Survival Times ◽  
Response Curves ◽  
Virus Particles ◽  
The Best Approximation ◽  
Graded Responses ◽  
Quantal Responses ◽  
Random Variation

The sensitivity of quantal and graded responses to mouse-adapted bluetongue virus for the detection of neutralizing antibody was compared using probit and rankit analysis. The graded response, based on survival times, allowed the demonstration of antibody in highly dilute serum, in which antibody was not detected by the quantal response recording percentage death.Quantal responses to bluetongue virus variants were compared with theoretical dose-response curves constructed according to the Poisson distribution for the random variation of virus particles in inocula. Of these theoretical curves the first term in the Poisson distribution gave the best approximation to the experimental data but the fit to normal distribution curves was better. The quantal responses to bluetongue virus did not appear to reflect the random variation of one-or-more infectious virus particles in inocula.In graded responses to bluetongue virus, a rectilinear relationship was observed between reciprocal harmonic means of survival times and log virus dilutions.

Observations on breeding sites and light-trap collections of Culicoides during an outbreak of bluetongue in Cyprus

1979 ◽  
Vol 69 (2) ◽  
pp. 229-234 ◽  
Author(s):  
P. S. Mellor ◽  
G. Prrzous
Keyword(s):  
Bluetongue Virus ◽  
Virus Disease ◽  
Close Association ◽  
Light Trap ◽  
Light Traps ◽  
Breeding Sites ◽  
Sheep And Goats ◽  
Species Being

AbstractDuring an epizootic of bluetongue virus disease of sheep in Cyprus in the autumn of 1977, 16 species of Culicoides were collected in light-traps and 4 species were collected from breeding sites. Two of the species found breeding in close association with sheep and goats are potential vectors of bluetongue virus. The possibility of a third species being a vector in Cyprus is discussed.

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