The Iranian isolate of tomato leaf curl virus (TLCV-Ir; GenBank Acc. No. AY297924) is a whitefly (Bemisia tabaci) transmitted begomovirus causing leaf curl disease of tomato in Iranshahr (Sistan and Baloochestan province, Iran). To test the infectivity of a full-length 2763 nucleotide DNA of this virus, a partial dimer (head-to-tail) was constructed in the binary vector pBin19 and transferred into Agrobacterium tumefaciens strain C58. A range of potential hosts including Lycopersicon esculentum, Nicotiana tabacum, N. benthamiana, Datura stramonium and some other indicator plants were agroinoculated with a bacterial culture of this construct. Mild curling and yellowing symptoms were observed on newly developed leaves of tomato plants within 30 to 45 days post-inoculation (dpi). However, the next phase of symptom development on tomato occurred 2-3 months after inoculation and produced elongated spindly shoots, smaller leaves and severe leaf cupping on the newly developed leaves. N. benthamiana plants agroinoculated with TLCV-Ir also showed severe symptoms including leaf curling and leaf cupping within 21 to 30 dpi. No symptoms were observed on other agroinoculated plants but dot blot and PCR analysis using TLCV-Ir-specific probes and primers, respectively, confirmed the presence of viral DNA in Datura stramonium and N. tabacum plants indicating that these plants are symptomless hosts of the TLCV-Ir. On the basis of host range, symptom severity, timing of symptom appearance and the level of replication of the virus in host plants in comparison with a severe isolate of TLCV, i.e., the Australian isolate of TLCV, TLCV-Ir is considered as a mild isolate. Transmission of TLCV-Ir from agro-infected tomato plants to healthy tomato seedling was achieved with one adult of B. tabaci and the inoculated plants showed typical symptoms of the disease. The infectious clone of TLCV-Ir can be used as a source of this virus in various studies including screening of resistance cultivars.

Communicable diseases cause 45% of deaths in developing countries, and vaccination is the best way to prevent it. However, current methods of vaccine production are complex and expensive, which makes vaccination inaccessible to poor countries. Recently, plant-based oral vaccines have been proposed as a new method. In this method, antigen genes are attached to plant viruses and used to produce vaccines in plants. Plants are a safe, efficient and inexpensive production platform through which vaccines and other therapeutic proteins can be produced for poor and developing countries of the world. Plant virus-based expression vector technology is one of the most popular methods for expressing pharmaceutical proteins in plants, in which several oral vaccines are reviewed. Advanced virus-based expression systems, especially GEMINIVIRUSes in plants for vaccine production. Advantages of single-stranded and small DNA viruses. Progress in the design of several different expression viral vectors based on GEMINIVIRUSes and examples of vaccines and other biological materials are discussed. Finally, the advantages and challenges of producing oral vaccines in medical science are discussed.

GEMINIVIRUSes cause curly top disease, in dicotyledonous plants which constrains host crop production. Beet curly top Iran virus (BCTIV) is a widespread Becurtovirus (family Geminiviridae) in numerous areas within Iran. In this study, we isolated and analyzed a full-length genomic DNA of a new variant of BCTIV from pepper crops in the Kaftark region, east of Shiraz (proposed acronym: BCTIV-Kaf [IR: Kaf: 2016: Pepper]). Infected pepper plants showed shortening of internodes, severe interveinal chlorosis, upward leaf rolling and leaf curling. Sequence and phylogenetic analysis showed this BCTIV variant grouped with sugar beet isolates of BCTIV and has the highest similarity to a sugar beet BCTIV isolate from Negar town in Kerman province, Iran. It was more distantly related to a bean isolate of BCTIV from northeast region of Iran. A tandem repeat partial dimmer of BCTIV was constructed and found to be infectious in pepper, tomato and Nicotiana benthamiana plants. Results of this study indicated that BCTIV-Kaf is a new variant of BCTIV infecting pepper plants in Shiraz and that geographic location rather than the type of host plant has more effect on genetic diversity of BCTIV in Iran.

Beet curly top Iran virus (BCTIV, genus Becurtovirus) and Beet severe curly top virus (BSCTV-IR, genus Curtovirus) induce beet curly top disease in different regions of Iran. In addition to sugar beet, tomato and pepper are important hosts of these viruses. Also tomato yellow leaf curl disease (TYLCD) is a serious disease of tomato in Iran. The Iranian isolate of Tomato yellow leaf curl virus (TYLCV-[Ab]), a severe strain of TYLCV (genus Begomovirus), is a major component of TYLCD in southern Iran. Until now, no information is available regarding comparative host range of these viruses. To determine the natural hosts of BSCTV-IR, BCTIV and TYLCV-[Ab], samples of sugar beet, tomato, pepper, turnip and spinach were collected from different regions in Fars province. For the experimental host range determination, a number of plants were grown in the greenhouse and their seedlings were agroinoculated with the infectious clone of each virus. The results showed that BSCTV-IR has a wider natural and experimental host range compared to BCTIV. These results indicated that member of Solanaceae, Brassicaceae, Fabaceae and Amaranthaceae are most frequently infected by BSCTV-IR and BCTIV. Natural host range of TYLCV-[Ab] seemed to be very narrow as, in the present study, this virus was isolated only from tomato. However, under greenhouse conditions, bean, nasturtium, petunia, redroot pigweed, datura, night shade and ground cherry were found to be infected by this virus.

The effect of various temperatures on the infection of sugar beet plants by Iranian isolate of Beet severe curly top virus (BSCTV-IR) was evaluated. Presence of BSCTV-IR in agroinoculated plants was assayed at 7, 14 and 21 days post-inoculation (dpi) using PCR. Based on the infectivity assay, the optimum temperature for BSCTV-IR infection was 25oC at which the mean period between inoculation and the first virus detection was the shortest and the virus concentration was the highest. No virus was detected in plants incubated at 35oC until 21 dpi. To evaluate the effect of temperature on recovery of BSCTV-IR-infected plants, symptomatic plants were incubated at the aforementioned temperatures. The first new leaf showing recovery phenotype emerged 7 dpi at 35oC. This period for plants incubated at 30, 25-30, 25 and 20oC was 12, 18, 25 and 28 days post-incubation, respectively. Thus, recovery occurred faster as the temperature raised. Re-inoculation of recovered plants with the same virus induced no symptoms in newly emerging leaves, indicating the stability of the phenotype of recovered plants against re-infection by the same virus. Quantitative analysis using real-time PCR showed significant decline in viral DNA in either recovered or new leaves emerged after re-inoculation compared to symptomatic leaves.

In order to evaluate the effect of sugar beet genotype and method of plant inoculation on resistance to Iranian isolate of Beet severe curly top virus (BSCTV-Ir), a completely randomized experimental design was performed using 18 sugar beet cultivars. Eighteen plants of each cultivar were grown in 6 pots. Two methods of inoculation, namely, agroinoculation using the infectious clone of BSCTVIr and inoculation by viruliferous leafhopper (Circulifer haematoceps) were used. The virus replication in inoculated plants was analyzed by PCR, 21 and 35 days post-inoculation (dpi) in the first experiment and 21 dpi in the second experiment. The severity of disease symptoms of inoculated plants was graded using a 0-3 scale (0, symptomless; 1, mild; 2, moderate and 3 severe symptoms). Data analysis of the first experiment indicated that the cv Brigita was the only cultivar in which all the inoculated plants were infected by the virus and all of them showed severe symptoms. Consequently, this cultivar was considered as a highly sensitive control cultivar and used in comparisons. Statistical analysis of the disease symptom severity index showed highly significant differences among cultivars when compared with the control cultivar. As a result, three distinct groups were identified. The first group including the cultivars BR1, FIMMA, HM1990, 7233, and H5505, and the second group including the cultivars Rasoul, Afshari, hybrid of Balk Shiraz, P.P.8, P.P.22, Dorothea, Zarghan, Rhizofouret, IC, Flores, Hilma and Polyrow were regarded as tolerant and sensitive groups, respectively. The third group included only Brigita cultivar which was regarded as very sensitive. Comparison of the data obtained from two inoculation methods indicated that in most cultivars, the virus infection rate was lower with vector inoculation than with agroinoculation.

Tomato leaf curl virus (TLCY, Family Geminiviridae, genus Begomovirus) is a whitefly (Bemisia tabaci) transmitted GEMINIVIRUS (WTG) causing a destructive disease of tomato in many regions of India, East Asia and Australia. While TLCY isolates from Australia, Bangalore (India) and Taiwan and Tomato yellow leaf curl virus (TYLCY) isolates from different regions of Asia, Europe and America have a single genomic component (designated DNA A), those from Northern India and Thailand have two components (DNA A and DNA B). Previously, TYLCY-like GEMINIVIRUSes have been identified from southern provinces of Iran causing leaf curling, stunting, and severe reduction in fruits of tomato plants in the fields. We have used degenerate DNA A specific PCR primers to clone part of the genome of an Iranian isolate of TLCY (TLCY-Ir) from field-infected tomato plants growing in Iranshahr, Sistan-Baluchestan Province. Degenerate DNA B-specific PCR primers did not amplify a putative DNA B from infected tomato under conditions that DNA B fragments were amplified from plants infected with Tomato golden mosaic virus, a known bipartite begomovirus. The full-length 2763 nucleotide DNA A genome of TLCY-Ir was sequenced and compared to Iranian isolate of TYLCY (TYLCY-Ir, previously sequenced by Bananej et al., (GcnBank accession No. AJ 132711) isolated from tomato in the same region.As other monopartite TLCV and TYLCV isolates, both TLCV-Ir and TYLCV-Ir genomes contain six open reading frames, two on the virion-sense strand and four on the complementary-sense strand. Sequence comparisons indicated that TLCV-Ir is substantially different from TYLCV-Ir with only 79% nucleotide sequence identity. Phylogenetic analysis showed while the TYLCV-Ir represents an isolate of TYLCV-Israel (TYLCV-Is) group, the TLCV-Ir is closer to TLCV isolates from southern India (TLCVs-Bangalore 2-5) which are most similar to other WTGs infecting tomato and cotton in Pakistan, India and East Asia and differ substantially from T(Y)LCVs of the Middle East, America, Europe and Australia.Presence of two tomato - infecting begomoviruses in the same area provides a favorable environment for recombination of these viruses.

Plants are a safe, efficient, and inexpensive production medium through which vaccines and other therapeutic proteins can be prepared for poor and developing countries. Plant virus-based expression vector technology has quickly become one of the most popular ways to express medicinal proteins in plants. In this study, several oral vaccines prepared in the world is reviewed and then the advanced expression system based on viruses, especially GEMINIVIRUSes and viruses in plants to make vaccines is discussed. This review also provides an overview of the benefits of single-stranded and small-stranded DNA viruses and compares their benefits for the expression of drug proteins with other expression systems in other plant viruses. The following is a breakthrough in the design of several different viral expression vectors of mutiny, GEMINIVIRUSes and viruses in the world and in Iran, and examples of vaccines and other biological materials produced from each are described. Finally, the benefits and challenges of producing oral vaccines in medical science are discussed.