A Breakthrough in Kitavirids: Genetic Variability, Reverse Genetics, Koch's Postulates, and Transmission of Hibiscus Green Spot Virus 2

Hibiscus green spot virus 2 (HGSV-2), a member of the genus Higrevirus (family Kitaviridae), is a positive-stranded RNA virus associated with leprosis-like symptoms in citrus and green spots on leaves in hibiscus. HGSV-2 has only been reported in Hawaii, and while it is speculated that mites in the genus Brevipalpus might be responsible for its transmission, proper transmission assays have yet to be conducted. This study characterizes additional citrus and hibiscus isolates of HGSV-2 collected from two Hawaiian Islands. We constructed an infectious cDNA clone from a hibiscus isolate of HGSV-2 collected on Oahu and demonstrated its ability to infect several experimental hosts, including Phaseolus vulgaris, Nicotiana tabacum, and N. benthamiana, as well as natural hosts, Citrus reticulata and Hibiscus arnottianus. Bacilliform virions with varied sizes of 33 to 120 nm (length) and 14 to 70 nm (diameter) were observed in partially purified preparations obtained from agroinoculated leaves. Virus progeny from the infectious cDNA clone was found to be infectious after mechanical transmission to N. benthamiana and to cause local lesions. Finally, an isoline colony of the mite Brevipalpus azores had vector competence to transmit a citrus isolate of HGSV-2 collected from Maui to citrus and hibiscus plants, demonstrating the mite-borne nature of HGSV-2. The infectious cDNA clone developed in this study is the first reverse-genetics system for a kitavirid and will be fundamental to better characterize basic biology of HGSV-2 and its interactions with host plants and mite vectors.

Applicability of Different Methods for Quantifying Virucidal Efficacy Using MENNO Florades and Tomato Brown Rugose Fruit Virus as an Example

After entry of a quarantine/regulated pathogen, infected plants shall be destroyed, and the cultivated area (e.g., greenhouse) shall be disinfected. Therefore, the selection of an effective disinfectant plays an important role. With the availability of different methods for virus quantification, we investigated the application of quantitative ELISA (qELISA), RT-qPCR (reverse transcription-quantitative polymerase chain reaction), and bioassays for the quantification of disinfectant efficacy. Therefore, we estimated the titer reduction in tomato brown rugose fruit virus (ToBRFV), a regulated pathogen, in plant sap and on germ carriers after treatment with MENNO Florades 4% for 16 h. The virus load before and after the treatment was measured with the mentioned methods. The RT-qPCR and qELISA methods showed very low efficacy in the presence of the disinfectant. Although bioassays are time-consuming, need purified particles for establishing the quantification models, and are less sensitive than RT-qPCR, they were able to quantify the differences in virus titer in the presence/absence of disinfectant. Interestingly, the bioassays reached at least the lower limit sensitivity of a qELISA. By being less sensitive to the presence of the disinfectant, bioassays proved to be the only technique for the determination of the disinfectant efficacy against ToBRFV on different germ carriers as well as on virus-infected plant sap.

游离腓动脉嵌合穿支皮瓣修复腮腺癌晚期局部病变术后缺损

OBJECTIVE

To investigate the effectiveness of free peroneal artery chimeric perforator flap in repairing the defect after advanced local lesions resection in parotid gland carcinoma (PGC).

METHODS

Between June 2010 and June 2020, 32 patients with advanced local lesions of PGC were treated with extended radical resection. After that, 17 patients were repaired with the free peroneal artery chimeric perforator flaps (trial group) and another 15 patients were repaired with the pedicled pectoralis major myocutaneous flaps (control group). There was no significant difference in gender, age, disease type, histopathological classification, clinical stage, and pathological stage between groups ( P>0.05). The size of skin flap in trial group ranged from 7 cm×6 cm to 12 cm×8 cm and the size of soleus muscle flap ranged from 5 cm×3 cm to 6 cm×4 cm. The donor sites were repaired with skin grafting. The size of the pedicled pectoralis major myocutaneous flaps in control group ranged from 9 cm×6 cm to 14 cm×7 cm. The donor sites were sutured directly. The operation time, survival rate of flap, and postoperative survival of patients were recorded and compared between groups. At 1 year after operation, the University of Washington quality of life (UW-QOL) questionnaire was used to evaluate the quality of life of patients in the two groups, including appearance, shoulder movement, sociability, masticatory function, speech function, and mood.

RESULTS

The operations completed successfully. The operation time was (6.19±0.72) hours in trial group and (6.41±0.71) hours in control group, showing no significant difference between groups ( t=-0.863, P=0.395). The survival rate of flap in trial group was 94.1% (16/17); and 1 patient suffered from vascular crisis after operation and was replaced with the pedicled pectoralis major myocutaneous flap. The survival rate of flap in control group was 100%. All grafts survived and the incisions healed by first intention in the two groups. All patients were followed up. The follow-up time was 6-60 months (median, 60 months) in trial group and 7-60 months (median, 60 months) in control group. Cumulative survival rates of patients at 1, 3, and 5 years after operation were 94.1%, 64.7%, and 58.8% in trial group, respectively; 86.7%, 66.7%, and 53.3% in control group, respectively. There was no significant difference in the cumulative survival rate between groups ( χ ²=0.090, P=0.762). According to the UW-QOL questionnaire at 1 year after operation, the scores of appearance, shoulder movement, sociability, and mood in trial group were significantly higher than those in control group ( P<0.05); and there was no significant difference in masticatory function and speech function scores between groups ( P>0.05).

CONCLUSION

The peroneal artery perforator has an invariable anatomical relationship. Each perforator emits the muscular branch that nourishes the soleus muscle. Therefore, personalized free peroneal artery chimeric perforator flap can be designed according to the tissue defect, and used to repair the defect after advanced local lesions resection in PGC.