Mouse Fibroblast L929 Cell Line as a Useful Tool for Replication and Adaptation of Infectious Bursal Disease Virus.

Infectious bursal disease virus (IBDV) causes a highly contagious disease associated with immunosuppression in young chickens. Production of either egg-based or primary cell-based high-quality vaccines requires time-consuming and costly procedures. To determine a suitable cell line for IBDV replication, L929 cell line was a candidate for the growth kinetics processing of the virus. The L929 cells were proliferated in monolayer, and doubling time was calculated. Replication kinetics an IBDV isolate at the multiplicity of infection 0.1 PFU/cell were determined using virus titration. To adapt IBDV on L929 cells, seven consecutive passages were performed. Virus titer and levels of apoptosis were quantitatively analyzed at each passage. The viral VP2 gene was amplified and sequenced in three passages. An average doubling time of 21 h was estimated for monolayers of L929 cells. Although during early passages, virus growth did not produce a clear cytopathic effect (CPE), an increase in IBDV titers was observed. Serial passages led to the evidence of marked CPEs and an increase in the virus titer in the third passage. During the fourth to seventh passages, consistent CPEs characterized by the formation of granulated and round cells were evident within 24 to 48 hours post-inoculation. The titer of the virus was increased in the third passage onwards to peak in the fourth and constant at 5.9 TCID50 until the end passage. The IBDV replication in connection with DNA fragmentation and FITC, revealed the characteristic picture of apoptosis in a time-dependent manner. We found that the IBDV could easily be adapted to L929 cells, increasing virus yields by about two orders of magnitude. These results indicated that the cell line may be useful in the production of efficient virus particles.

Genetic and Antigenic Evaluation of Foot-and-mouth Disease Virus Type A in the Endemic Area of Iran within 2014-2015.

The foot-and-mouth disease virus (FMDV) with a wide variety of genomes and complicated biology is one of the infectious agents that put the lives of animals at risk. Therefore, to introduce suitable strains for vaccine production, it is essential to constantly evaluate genetic changes of circulating viruses in field. Within 2014-2015, a total of 126 clinical specimens consisting of epithelial tissue and vesicular fluid from tongue, dental pad, and hoofs suspected of FMD virus were submitted to the Reference Laboratory for FMD in Razi Vaccine and Serum Research Institute, and 86 of them were identified as FMD virus type A using sandwich Enzyme-Linked Immunosorbent Assay (ELISA). This virus was isolated from 42 samples from 16 provinces using cell culture. Firstly, the coding region that produces the main part of viral capsid was amplified by Polymerase chain reaction (PCR). This part of the genome by 800 bp length was related to the 1D gene that synthesizes the VP1 protein. The phylogenetic analysis of VP1 coding region determined two distinct genotypes with more than 15% nucleotide differences. The first cluster consisted of closely related viruses registered in the GeneBank of neighboring countries, including Afghanistan, Pakistan, and Turkey. All samples in Cluster1 were determined as relative viruses with genotype Iran-05. In-vitro serological examination indicated an antigenic relationship between Cluster 1 viruses and routine vaccine strain (A-IRN-2013). The second cluster with only two members was genetically far from earlier ones and could be considered a separate genotype. Furthermore, it was revealed that cluster 2 has not been previously reported in Iran. Genetic tracing indicated that these viruses might have been originated from circulating viruses from India. Antigenic evaluation exhibited that this group could not be cross-protected by the routine vaccinal strain (A-IRN-2013) used during the research period.

Development of an Indirect Enzyme-linked Immunosorbent Assay to Detect Antibodies against Serotype A2013 of Foot and Mouth Disease Virus in Cattle.

Foot and mouth disease (FMD) is a contagious animal disease that causes irreparable damage to the economy of countries, including Iran in which this disease is a native one. Among the ways to combat FMD are vaccination and slaughter. Due to the specific situation of Iran, it is not possible to kill infected animals. Therefore, vaccination is the most important way to fight this disease. Serum neutralization test (SNT) and enzyme-linked immunosorbent assay (ELISA) are two main methods to evaluate the safety and calculate antibody titer. In this study, an indirect ELISA test was developed based on the coating of a complete viral particle (140s) which made it possible to determine antibody. In addition, serotype and viral type were determined without the need for time-consuming and complex molecular tasks, including gene expression. Moreover, in case of a new epidemic, a new epidemic condition can be detected using a serum antibody method. However, the coating of the complete viral particle leads to virus purification as well as the conjugated anti-immunoglobulin antibody testing of the same animal. In this study, the SNT was used as a gold standard test to determine the serum antibody level and compare its results with indirect ELISA method to determine the sensitivity and specificity of the indirect ELISA. To measure the anti-virus antibody rate of FMD (type A2013) through receiver operating characteristic analysis with 100% sensitivity and the specificity of 90%, the routine formulas were utilized using 100 % and 82%sensitivity and specificity, respectively. In this study, the cutoff value for the optical density was obtained at 0.3 and there was a significant difference between the vaccinated animals and the unvaccinated ones in terms of antibody level against the A2013 type. This indicates the correctness of the test and the accurate and proportional antibody detection against the understudy viral types of FMD.

An uncommon clinical form of foot-and-mouth disease in beef cattle presented with cornual skin lesions.

Foot-and-mouth disease (FMD) is a major infectious disease in livestock. The common clinical signs in cattle include epidermal vesicles that are majorly distributed around oronasal cavity, feet and teats. The aim of this report is to document an uncommon clinical form of the disease which comprises the occurrence of classic vesicular lesion in a rarely observed location of the horn vegetative tissue. During Iran's outbreak of FMD in 2013, field investigation, clinical examination and sampling from the affected herds in Qom province were performed. Specimens of mouth epithelium and horn vegetative tissue were collected for virology and histopathologic study. All the samples collected from horns were positive for foot-and-mouth disease virus (FMDV) in both enzyme linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) tests, and the strain of the virus was identified as A05. Surprisingly, all the animals with horn lesion came from beef herds, were less than 12 months old and had more severe signs of the systemic disease. Since the same strain of virus did not cause similar lesions in surrounding dairy cows, it was concluded that occurrence of horn lesions may be more associated with host factors rather than virus strain.

Evaluation of the efficacy of a new oil-based adjuvant ISA 61 VG FMD vaccine as a potential vaccine for cattle.

Foot-and-mouth disease is an important viral disease of cloven-hoofed animals. Inactivated whole particle virus vaccines are still widely used in prophylactic vaccination campaigns. The choice of adjuvant is a very important factor in enhancing immune responses and the efficacy of inactivated vaccines. Montanide ISA 61 VG is a new ready-to-use mineral oil-based adjuvant developed by SEPPIC Inc. (SEPPIC, France) with high-potential immune responses needed for clinical protection against FMD infection. In this study, we compared the efficacy of two FMD vaccines either formulated with the new oil-based adjuvant ISA 61 VG and saponin, or with aluminum hydroxide gel and saponin. Both vaccines contained the same antigen payloads of O2010/IR. Two groups of 15 naive cattle received a single vaccination with different doses (full dose, 1/3 dose and 1/9 dose) to calculate their PD50 (50% protective dose) after being challenged with the homologous virulent virus. The mean neutralizing antibody titer was determined at 0, 7, 14 and 21 days after vaccination, measured by a micro neutralization test. The new vaccine improved humoral immune responses by 19%, while inducing a higher geometric mean. The titer for neutralizing antibodies was 2.91 log10 compared to the alum-gel based adjuvant vaccine which was 2.44 log10 (P-value=0.1782). The new vaccine showed a PD50 value of 10.05 as compared to a PD50 value of 4.171, respectively. According to the results, the FMD vaccine formulated with the new oil adjuvant, ISA 61 VG, shows potential as an alternative vaccine for routine and emergency vaccinations in the FMD enzootic region.

Sequence analysis of the foot and mouth disease virus type O/IRN/2007 VP1 gene from Iranian isolate.

The foot and mouth disease virus (FMDV) causes a vesicular and contagious disease of cloven-hoofed animals. In this study, the virus was isolated from vesicles of the infected cattle using cell culture and serotyped by ELISA test. The extracted RNA from the infected cells was reverse transcribed and amplified using VP1 gene-specific primer pairs by means of one-step RT-PCR. The purified VP1 gene was sub-cloned into the uniqe KpnI and BamHI cloning sites of the pcDNA3.1+ vector. The DH5α strain of E. coli was transformed by the vector. The sequences of sub-cloned FMDV type O/IRN/2007 VP1 were aligned with FMDV type O/UKG/2001 VP1 using MegAlign software. Nucleotide sequence comparisons were made using the BLAST software available from the NCBI website. The amino acid sequences of three sub-cloned FMDV type O/IRN/2007 VP1 were also aligned with three other similar sequences using MegAlign software. Nineteen of the most similar VP1 nucleotide sequences (by BLASTN program), FMDV O/IRN/2007 VP1 sequence, twenty isolates of FMDV-O VP1 in Iran and eight topotypes of FMDV type O were aligned by Mega5 to create a FMDV-O VP1-based sequence similarity tree. The nucleotide sequence comparison indicated that FMDV O/ IRN/2007 VP1 had the greatest nucleotide sequence similarity to the VP1 gene of FMDV O1/Manisa/Turkey/69 (99%), FMDV O1/Manisa/Netherlands (98%) and FMDV O1/Manisa/iso87/Turkey (98%). It was also observed that the highest identity between FMDV O/IRN/2007 VP1 sequence and other nucleotide sequences of FMDV type O VP1 genes isolated in Iran during 1997-2004 was about 91%.