Large-scale seroprevalence and risk factors associated with Bluetongue virus in Iran.

Bluetongue virus (BTV) remains as an economically major concern in the world. Seroprevalence and potential risk factors of BTV were assessed in a cross-sectional study at both the herd and animal levels in Iran. A total of 73 Epidemiologic Units (E.Unit), defined as a herd, flock or village including animals with equal chance of exposure to infectious agents, were randomly selected. Serum samples from all animals (n = 34,575) within the E.Units were collected and tested for BTV sero-group antibodies by using commercially competitive ELISA test. Using cluster analysis, 90.41 % (95 %, CI: 80.85 %-95.47 %) of the E.Units and 56.13 % (95 % CI: 55.61 %-56.66 %) of the tested animals were detected seropositive against BTV. A seroprevalence rate of 57.59 % (95 % CI: 48.01 %-66.63 %), 65.65 % (95 % CI: 59.10 %-73.74 %) and 27.63 % (95 % CI: 14.40 %-46.43 %) was estimated for sheep, goats and cattle, respectively. At E.Unit (herd) level, density was identified as a great risk factor for the infection (r2 = 0.891; P = 0.000), and particularly density of cattle significantly correlated with BTV infection within the E.Units (r2 = 0.247; P = 0.019). Using multilevel logistic regression, adjusted odds ratios (ORs) were estimated at individual level. A significantly less risk of BTV infection was evaluated for cattle than for sheep (OR = 0.42, 95 % CI: 0.38-0.47, P < 0.001), while no significant difference was observed between sheep and goat (OR = 1.03, 95 % CI: 0.97-1.10, P = 0.345). Animals over 2 years and between 6 months and 2 years expressed 2.22 (OR = 2.22, 95 % CI: 1.96-2.52, P < 0.001) and 2.18 (OR = 2.18, 95 % CI: 1.92-2.49, P < 0.001) times higher chance for the infection than animals under 6 months. Males were at significantly less risk of the infection than females (OR=0.68, 95 % CI: 0.63-0.74, P < 0.001). Animals kept in industrial farming systems displayed 0.46 (OR=0.46, 95 % CI: 032-0.66, P < 0.001) times less chance than animals kept in traditional farming system for BTV, while animals lived in semi-industrial farming system were found to be at 2.97 (OR=2.97, 95 % CI: 2.41-3.66, P < 0.001) times higher chance for BTV than animals lived in traditional farming system. Furthermore, seropositive animals exhibited a high amount of antibodies against BTV (s) suggesting that viral exposure may have frequently occurred during their lifetimes. This large - scale study yielded information on epidemiology of BTV in Iran that is prerequisite for further research, and also for evaluation of any cost-benefit control measure to be established in an enzootic zone of the virus.

Phylogenetic analysis of small ruminant lentiviruses in Germany and Iran suggests their expansion with domestic sheep.

Small ruminant lentiviruses (SRLVs) are found in sheep in Germany and Iran. SRLVs have been classified into four genotypes: A-C and E. Genotype A has been subdivided into 20 subtypes. Previous studies suggested that, first, the ancestors of genotype A are those SRLVs found in Turkey, second, the evolution of SRLVs is related to the domestication process, and, third, SRLV infection was first observed in sheep in Iceland and the source of that infection was a flock imported from Germany. This study generated, for the first time, partial SRLV sequence data from German and Iranian sheep, enhancing our knowledge of the genetic and evolutionary relationships of SRLVs, and their associations with the domestication process. Based on 54 SRLV sequences from German and Iranian sheep, our results reveal: (1) SRLV subtypes A4, A5, A11, A16 and A21 (new) are found in German sheep and A22 (new) in Iranian sheep. (2) Genotype A has potentially an additional ancestor (A22), found in Iran, Lebanon and Jordan. (3) Subtype A22 is likely an old version of SRLVs. (4) The transmission routes of some SRLVs are compatible with domestication pathways. (5) This study found no evidence of Icelandic subtype A1 in German sheep.

Lentivirus Susceptibility in Iranian and German Sheep Assessed by Determination of TMEM154 E35K.

Small ruminant lentiviruses (SRLVs) cause maedi-visna disease in sheep and are prevalent in Iran and Germany. The association of the transmembrane protein 154 (TMEM154) variants with SRLV infection has been previously identified by a genome-wide association (GWAS) approach and subsequent analyses, and validated in some US, German, and Turkish sheep flocks. We aimed at evaluating these findings for the first time in Iranian, and in some more German sheep flocks/breeds. Also, we aimed at comparing the SRLV susceptibility in Iranian and German sheep based on the frequency of the TMEM154 E35 allele. About 800 blood samples were collected from 21 Iranian and German sheep flocks/breeds for different purposes: (1) The association of TMEM154 E35K with SRLV infection status was tested in four sheep breeds and found to be significant in Kermani, Merinoland, and Brown Hair. (2) The usefulness of the TMEM154 E35 frequency for predicting SRLV susceptibility was evaluated by regression analysis, combining data from this study and some already published data. Results showed a significant association between E35 frequency and SRLV prevalence. (3) SRLV susceptibility was compared based on E35 frequency in Iranian and German sheep. Altogether, findings of this study provide valuable information on SRLV susceptibility, using TMEM154 E35, in Iranian and German sheep.

Molecular prevalence of bovine noroviruses and neboviruses in newborn calves in Iran.

In this study, bovine enteric caliciviruses (BECs) were detected in 49.4% of a total of 253 stool specimens for diarrheic calves collected from 42 industrial dairy farms from March 2010 to February 2012. Genogroup III norovirus (NoVsGIII) were more prevalent (39.5%) than neboviruses (NBs) (15%), and coinfections were observed in 5.1% of the samples tested. Sequence analysis of the partial polymerase gene from 13 NoVsGIII samples indicated the circulation of both genotype 1 and genotype 2 strains. Among the six NB strains sequenced, five were related to the Bo/Nebraska/80/US strain, while one was related to the Bo/Newbury1/76/UK strain.

The molecular epidemiology of bovine rotaviruses circulating in Iran: a two-year study.

Bovine group A rotavirus (bovine RVA) is recognized as a major cause of severe gastroenteritis in newborn calves. The purpose of this study was to estimate the prevalence and identify the genotypes of circulating bovine RVA in newborn diarrheic calves. Two hundred fifty-three stool samples of diarrheic calves up to 1 month old were collected from 42 industrial dairy farms in two Iranian provinces during March 2010 to February 2012. All collected samples were screened for the presence of bovine RVA by RT-PCR, and the G and P genotypes were determined by semi-nested multiplex RT-PCR assay. The results of RT-PCR indicated that 49.4 % (125 out of 253) of the samples were positive for bovine RVA. The G and P genotyping of a subset of positive samples (n = 85) by semi-nested multiplex RT-PCR revealed that G6 (55.3 %) and G10 (43.5 %) and P[5] (51.8 %) and P[11] (27 %) were the most prevalent G and P genotypes, respectively. G6P[5] was the dominant genotype (35.3 %), followed by G10P[5], G10P[11] and G6P[11], with prevalence rates of 16.5 %, 15.3 % and 10.6 %, respectively. Sequence analysis of 20 VP7 and four VP4 genes showed highest nucleotide sequence identity with the corresponding genes of strains RVA/Cow-tc/GBR/UK/1973/G6P7[5] and RVA/Cow-tc/USA/B223/XXXX/G10P[11]. The results of this study reveal the diversity of G and P genotypes in bovine RVA samples from diarrheic Iranian calves and expands our knowledge of bovine RVA infections in the Middle East. These results also highlight the importance of producing of an effective rotavirus vaccine and its inclusion in the national cattle immunization program.

Impact of Climate and Environmental Factors on West Nile Virus Circulation in Iran.

BACKGROUND: Geographic distribution of West Nile virus (WNV) is heterogeneous in Iran by a high circulation in the southern-western areas. The objective of our study was to determine environmental and climatic factors associated with the risk of WNV equine seropositivity in Iran. METHODS: Serological data were obtained from a serosurvey conducted in equine population in 260 districts in Iran. The climate and environmental parameters included in the models were distance to the nearest wetland area, type of stable, Normalized Difference Vegetation Index (NDVI), annual mean temperature, humidity and precipitation. RESULTS: The important risk factors included annual mean temperature, distance to wetlands, local and seasonal NDVI differences. The effect of local NDVI differences in spring was particularly notable. This was a normalized difference of average NDVI between two areas: a 5 km radius area centered on the stable and the 5-10 km surrounding area. CONCLUSION: The model indicated that local NDVI's contrast during spring is a major risk factor of the transmission of West-Nile virus in Iran. This so-called oasis effect consistent with the seasonal production of vegetation in spring, and is associated to the attractiveness of the local NDVI environment for WNV vectors and hosts.