1380. Real-world Effectiveness and Complications of Valganciclovir (VGC) Prophylaxis for Kidney Transplant (KT) Recipients at High Risk for Cytomegalovirus (CMV) infection (CMV Donor (D)+/Recipient (R)-)

Background CMV infection is common post-kidney transplant (KT). Valganciclovir (VGC) prophylaxis (Px) has lessened CMV infection among high-risk (CMV D+/R-) KT recipients (KTRs), but VGC can induce neutropenia. We quantified the burden of CMV infection among CMV D+/R- KTRs and healthcare resources required to manage these patients (pts). Methods Retrospective study of pts undergoing KT between Jan 2014-Dec 2018. Study and control groups (gps) were CMV D+/R- and R+ KTRs, respectively. Standard post-KT immunosuppression was tacrolimus and mycophenolate mofetil (MMF). D+/R- and R+ KTRs received VGC Px (900 mg/day) for 6 and 3 months (mos), respectively. Results Clinical characteristics did not differ between D+/R- (n=131) and R+ (n=140) pts. Median VGC Px duration was longer for D+/R- (183 vs 104 days, p< .01). Within the first 6 mos post KT, a higher proportion of D+/R- KTRs received ≥1-course of granulocyte-stimulating factor (G-CSF) (15% vs 6%, p=.02). VGC Px was stopped prematurely/intermittently in 20% and 10% of D+/R- and R+, respectively, due to neutropenia (p=0.02); corresponding data for stopping MMF for ≥1 mos were 32% and 21% (p=.05). 50% of D+/R- pts received < 3 mos Px. Leukopenia prompted hospitalization in 3% of D+/R- vs 0% of R+ pts (p=.05). CMV infections did not differ between gps (7% vs 6%, p=.80); however, VGC-resistant CMV was higher in D+/R- gp (3% vs 0%, p=.05). Between 6-12 mos post-KT, D+/R- KTRs had higher rates of CMV infection (24% vs 4%,p< .01), VGC resistance (5% vs 0%, p=.01), hospitalization due to CMV (11% vs 2%, p=.01), MD intervention (22% vs 2%,p< .01), and infectious disease (ID) referral (8% vs 2%,p= .04). 57% of CMV resistance was observed in pts who prematurely stopped VGC. Hospitalizations were longer for CMV infections in D+/R- KTRs (8 vs 1 d, p< .01). There was a trend toward higher rejection for D+/R- KTRs (13% vs 6%, p=.09). Conclusion Universal VGC Px in D+/R- KTR remains challenging and requires significant resources for monitoring and intervention for neutropenia, including MD involvement and ID referral. Intermittent/premature stop of VGC may have led to VGC-resistant CMV,and stop of MMF may have led to a trend of higher cellular rejection at 1 yr. There is critical need for new CMV agents with a better safety profile. Disclosures Amit D. Raval, PhD, Merck and Co., Inc. (Employee) Yuexin Tang, PhD, JnJ (Other Financial or Material Support, Spouse’s employment)Merck & Co., Inc. (Employee, Shareholder) Cornelius J. Clancy, MD, Merck (Grant/Research Support) Minh-Hong Nguyen, MD, Merck (Grant/Research Support)

#50: Cytomegalovirus Retinitis Among Pediatric Hematopoietic Stem Cell and Solid Organ Transplantation Recipients: A Contemporary Review

Background Cytomegalovirus infection can cause significant morbidity and mortality after transplantation. Cytomegalovirus retinitis (CMVR) can be a major complication of tissue invasive CMV disease in transplant recipients. There are little data regarding the contemporary incidence and outcomes of CMVR among pediatric transplant recipients. Methods We performed a retrospective cohort analysis of allogeneic hematopoietic (allo-HCT) and solid organ transplant (SOT) recipients who received medical care at Nationwide Children’s Hospital (NCH) from 1/1/10–11/30/20 and had a diagnosis of CMVR to describe the incidence, timing post-transplant, ocular manifestations, management, and outcomes. Basic demographic and clinical data, pre-transplant donor/recipient CMV serostatus, and post-transplant CMV infection data were collected. Graft-specific CMV surveillance and prophylaxis strategies were performed according to NCH hospital guidelines. During the study period, quantitative plasma CMV PCR assays included copies/mL (2010–2013) and WHO international standard IU/mL (2013–2020). Results During the 10-year study period, 347 patients underwent allo-HCT (N=214) or SOT (N=133; heart N=46, liver N=36, kidney N= 52; 1 patient had concomitant kidney and liver transplantation); median age was 8.6 years [range 0.1–25.9] and 198 (56.5%) were male. In total, 98 patients had CMV DNAemia post-transplant, and CMVR was diagnosed in 3 (HCT=2, SOT=1), for an overall CMVR incidence of 0.86% among all transplant recipients and occurring in 3% of patients with CMV DNAemia. No CMVR was diagnosed in patients without CMV DNAemia. An ophthalmologic examination was performed in 58 (59%) of patients with any DNAemia compared with 67 (27%) of patients without DNAemia. CMVR was diagnosed on funduscopic examination a median of 183 days [range 34–512] post-transplant based on visual symptomatology (N=2) or by routine eye screening prompted by DNAemia (N=1). CMV DNAemia at the time of CMVR was 1,463 copies/mL, 3,000, and 14,204 IU/mL; all patients had prolonged (>3 months) CMV detection before CMVR. One SOT recipient had concomitant pathology confirming CMV gastrointestinal tract disease. Two of the 3 CMVR cases occurred in the setting of genotypic UL94 CMV resistance mutations (A594V, H520Q)(Figure 1). Two patients were already receiving CMV antiviral therapy (maribavir N=1; valganciclovir=1) at the time of CMVR diagnosis. After the CMVR diagnosis, all patients were prescribed systemic foscarnet. Adjunctive therapies included concurrent intravitreal antiviral therapy (ganciclovir N=1; foscarnet N=1) and adoptive immunotherapy with CMV antiviral specific T-cells (N=1, HCT). Improvement of ocular symptoms occurred in 2 patients at 15 and 20 days after starting targeted CMV antiviral therapy; one patient developed permanently impaired vision. Conclusion CMVR remains as an important complication in transplant recipients. Although CMVR incidence was low in our cohort of transplant recipients, it occurred most frequently in cases of CMV resistance, prolonged DNAemia, and led to permanent visual impairment in 1 of 3 patients. The development of resistant CMV may have a role in the occurrence, progression, and severity of CMVR. Additional pediatric-specific data are needed to better characterize CMVR and inform optimal prevention strategies.

Unexpected CMV replication kinetics in CMV- donor seropositive recipient seronegative liver transplant recipients receiving preemptive antiviral therapy

Background Detailed CMV kinetics in donor CMV-seropositive, recipient CMV-seronegative (D+R-) transplant recipients receiving preemptive therapy (PET) have not been fully defined. Methods The study population consisted of PET arm of a randomized CMV prevention trial in D+R- liver transplant recipients. CMV-DNA PCR assays were performed weekly for 100 days using a sensitive assay. Viral load and clinical parameters were compared for patients with or without high-level increase (defined as higher than the group median log10 increase in viral load from baseline after PET initiation). Results Among 79 patients, 93.6% (74/79) developed an increase from baseline viral loads of median 120 IU/mL to 3,350 IU/mL; 25.7% (19/74) of the patients had peak levels > 10,000 IU/mL. None of the patients with rise in viral load underwent testing for CMV resistance and viremia resolved with PET with valganciclovir. Patients with high-level increase in viral load had significantly lower rate of recurrent viremia than those without such increase (40%,16/40 vs. 71.8%, 28/39, p=0.004), respectively. Conclusions A majority of D+R- recipients had a marked increase in viral load after initiation of PET before resolution of viremia. This phenomenon is associated with lower rates of subsequent recurrent viremia and does not necessarily imply antiviral resistance.

Pepper Crop Improvement Against Cucumber Mosaic Virus (CMV): A Review

Cucumber mosaic virus (CMV) is a prevalent virus affecting the quality and yield of pepper, resulting in yield losses of greater than 80% during severe local epidemics. Cultural practices and the heavy use of agrochemicals are the most common control measures for CMV. Sources of resistance provide a practical reference and a basis for breeding for CMV resistance. Genetic factors underlying CMV resistance have been studied and advanced breeding lines and cultivars with improved resistance have been developed by traditional breeding methods. Additionally, QTLs or genes for CMV resistance have been identified and can be utilized for marker-assisted resistance breeding. This review focuses on status and prospect of CMV against different virus strains, host resistance, and its applied genetics. With the advent of novel technologies, more useful markers and precise approaches can facilitate the progress for improving CMV resistance in Capsicum.

Construction of a High-density Genetic Linkage Map and QTL Analysis of Resistance to Cucumber Mosaic Virus in Luffa cylindrica (L.) Roem. Based on Specific Length Amplified Fragment Sequencing

Background: Luffa cylindrica L. is an economically important vegetable crop that is consumed globally. Cucumber mosaic virus (CMV) is an important virus affecting Luffa spp. No specific high-density maps have been constructed owing to a lack of efficient markers. Furthermore, no genes or quantitative trait loci (QTLs) are reportedly responsible for CMV resistance in Luffa spp. The development of next-generation sequencing has enabled discovery of single nucleotide polymorphisms and high-throughput genotyping of large populations. Results: A total of 271.01 Mb pair-end reads were generated. The average sequencing depth was 86.19× in both maternal and parental lines, and 14.57× in each F 2 individual. When filtering low-depth specific locus amplified fragment (SLAF) tags, 100,077 high-quality SLAFs were detected, and 7,405 of them were polymorphic. Finally, 3,701 of the polymorphic markers were selected for genetic map construction, and 13 linkage groups were generated. The map spanned 1,518.56 cM with an average distance of 0.41 cM between adjacent markers. Our results also revealed that CMV resistance was regulated by QTLs. Based on the newly constructed high-density map, two loci located on chromosome 1 (100.072 ~ 100.457 cM) and 4 (42.475 ~ 44.398 cM) were identified to regulate CMV resistance in L. cylindrica . A gag-polypeptide of LTR copia-type retrotransposon was predicted as the candidate gene responsible for CMV resistance in L. cylindrica . Conclusions: A high-density linkage map of L. cylindrica was constructed using SLAF. QTL mapping based on CMV disease phenotypes of F 2 led to the identification of two QTL on chromosome 1 and 4, respectively. Kompetitive allele-specific PCR analysis of 60 F 2 individuals, which gave rise to F 2:3 individuals, was carried out. We found that the QTL on chromosome 1 was associated with CMV resistance. Mapping of CMV QTL combined with the transcriptomic sequence alignment identified a gag-polypeptide of LTR copia-type retrotransposon as the most likely causal gene.

Construction of a High-density Genetic Linkage Map and QTL Analysis of Resistance to Cucumber Mosaic Virus in Luffa cylindrica (L.) Roem. Based on Specific Length Amplified Fragment Sequencing

Background: Luffa cylindrica L. is an economically important vegetable crop that is consumed globally. Cucumber mosaic virus (CMV) is an important virus affecting Luffa spp. No specific high-density maps have been constructed owing to a lack of efficient markers. Furthermore, no genes or quantitative trait loci (QTLs) are reportedly responsible for CMV resistance in Luffa spp. The development of next-generation sequencing has enabled discovery of single nucleotide polymorphisms and high-throughput genotyping of large populations. Results: A total of 271.01 Mb pair-end reads were generated. The average sequencing depth was 86.19× in both maternal and parental lines, and 14.57× in each F 2 individual. When filtering low-depth specific locus amplified fragment (SLAF) tags, 100,077 high-quality SLAFs were detected, and 7,405 of them were polymorphic. Finally, 3,701 of the polymorphic markers were selected for genetic map construction, and 13 linkage groups were generated. The map spanned 1,518.56 cM with an average distance of 0.41 cM between adjacent markers. Our results also revealed that CMV resistance was regulated by QTLs. Based on the newly constructed high-density map, two loci located on chromosome 1 (100.072 ~ 100.457 cM) and 4 (42.475 ~ 44.398 cM) were identified to regulate CMV resistance in L. cylindrica . A gag-polypeptide of LTR copia-type retrotransposon was predicted as the candidate gene responsible for CMV resistance in L. cylindrica . Conclusions: A high-density linkage map of L. cylindrica was constructed using SLAF. QTL mapping based on CMV disease phenotypes of F 2 led to the identification of two QTL on chromosome 1 and 4, respectively. Kompetitive allele-specific PCR analysis of 60 F 2 individuals, which gave rise to F 2:3 individuals, was carried out. We found that the QTL on chromosome 1 was associated with CMV resistance. Mapping of CMV QTL combined with the transcriptomic sequence alignment identified a gag-polypeptide of LTR copia-type retrotransposon as the most likely causal gene.

Cucumber mosaic virus resistance and reproductive biology of brazilian melon accessions

In melon (Cucumis melo) the resistance to Cucumber Mosaic Virus (CMV) and the knowledge about reproductive characteristics are important for selection of genitors for breeding population. So, the objective was to investigate if different accessions of melon from a Brazilian germplasm bank have variability in resistance to CMV (FNY strain) and polymorphism in resistance loci markers, as well as whether there is genetic diversity on resistance and floral morphology descriptors and reproductive biology, aiming at genetic improvement. The symptoms induced by CMV were evaluated in 52 melon genotypes which were genotyped with three markers of single nucleotide polymorphisms related to CMV resistance. A sample of 24 genotypes was characterized for floral and reproductive descriptors. The significant variation in resistance levels allows classifying the accessions in five groups. The polymorphisms detected by the markers were independently distributed in these groups, consistent with the oligogenic quantitative expression of the melon’s resistance. There were significant differences between accessions in floral and reproductive descriptors. Through the Ward-MLM multivariate strategy, these accesses were distributed into seven groups with distinct reproductive characteristics, including variability in pollen viability. Therefore, there are Brazilian accessions of melon that have resistance to CMV, as well as variability in reproductive characteristics.