Herpesviruses (HV) are pathogens causing infections in humans and animals worldwide. Since it shares many common features with other HV, bovine HV type 1 (BoHV-1) was selected as a model to test the anti-herpesviral activity of medicinal plants.
Fifteen plants were chosen in this study for their medical, antibacterial and antiviral properties. The aim was to investigate ethanolic extracts from the selected medicinal plants for anti-BoHV-1 activity. The virucidal activities were evaluated by comparing the effect of noncytotoxic concentrations of extracts on BoHV-1 strain 1640 replication in Madin-Darby bovine kidney (MDBK) cells. Virucidal activity was determined by means of virus titration after exposure to the extracts. The extract of Desmodium canadense was found to be the most effective virucide – the 50% tissue culture infective dose (TCID50) after exposure was 3.75 log10 and the virus reduction factor was ≥5.0±0.25 log10. The extract of D. canadense was therefore chosen for further studies. Virus yield reduction assays showed that D. canadense extract had time-dependent and dose-dependent effects. It effectively reduced virus titre from 8.33 log10 to 4.67 log10 (p<0.01). The virucidal activity was also confirmed by real-time polymerase chain reaction (real-time PCR), where the number of threshold cycles (Ct) was inversely proportional to the virus titre in TCID50 The virucidal activity was also confirmed by real-time polymerase chain reaction (real-time PCR). This method showed that the number of threshold cycles (Ct) was inversely proportional to the virus titre (direct correlation with exposure time R=0.9321). The extract of D. canadense showed a high virus reduction capacity. In future, such active substances should be identified for the development of effective antivirals.
Cucumber mosaic virus (CMV; family Bromoviridae, genus Cucumovirus) is the most cosmopolitan plant virus occurring worldwide. In the present study, leaf samples showing deformations, mosaics, and chlorotic spots symptoms were collected from naturally infected Basella alba, Telfairia occidentalis and Talinum fruticosum in a home yard garden in Ibadan, Nigeria. Total nucleic acid was extracted from leaves and used as template for cDNA synthesis. RT-PCR was carried out using CMV-specific primers targeting RNA-1 segment. Samples were also tested by RT-PCR using Potyvirus and Begomovirus genusspecific primers. DNA fragments with the expected sizes of ~500 bp were amplified by using CMV-specific primers; however, the expected amplicons were not produced using specific primers used for the detection of potyviruses and begomoviruses. The nucleotide and deduced amino acid sequences obtained for the isolates studied contained 503–511 nt and 144 aa, respectively. The isolates shared 81.9–85.3% nucleotide and 74.3–77.8% amino acid sequence identities with each other. The results of BLASTN analyses showed the highest identities of the isolates (80–93%) with CMV strains from Japan, USA and South Korea. Alignment of deduced partial protein revealed multiple amino acid substitutions within the three isolates and high identities with CMV subgroup I. Phylogenetic analyses putatively categorized the isolates in close association with subgroup IB isolates. The three isolates clustered together into a separate subclade, indicating possible new CMV strains. The results provide the first molecular evidence for CMV infections of T. fruticosum and B. alba in Nigeria and seem to show the possible presence of new strain(s). These findings also add three new hosts to the list of natural host range of the virus in Nigeria.