Novelties for the management of cytomegalovirus after kidney transplantation / Nouveautés dans la prise en charge du cytomégalovirus après transplantation rénale.

Cytomegalovirus (CMV) infection is the main opportunistic infection observed after kidney transplantation. Despite the use of prevention strategies, CMV disease still occurs, especially in high-risk patients (donor seropositive/recipient seronegative). Patients may develop complicated CMV, i.e. recurrent, refractory or resistant CMV infection. CMV prevention relies on either universal prophylaxis or preemptive therapy. In high-risk patients, universal prophylaxis is usually preferred. Currently, valganciclovir is used in this setting. However, valganciclovir can be responsible for severe leucopenia and neutropenia. A novel anti-viral drug, letermovir, has been recently compared to valganciclovir. It was as efficient as valganciclovir to prevent CMV disease and induced less hematological side-effects. It is still not available in France in this indication. Recent studies suggest that immune monitoring by ELISPOT or Quantiferon can be useful to determine the duration of prophylaxis. Other studies suggest that prophylaxis may be skipped in CMV-seropositive kidney-transplant patients given mTOR inhibitors. Refractory CMV is defined by the lack of decrease of CMV DNAemia of at least 1 log10 at 2 weeks after effective treatment. In case of refractory CMV infection, drug resistant mutations should be looked for. Currently, maribavir is the gold standard therapy for refractory/resistant CMV. At 8 weeks therapy and 8 weeks later, it has been shown to be significantly more effective than other anti-viral drugs, i.e. high dose of ganciclovir, foscarnet or cidofovir. However, a high rate of relapse was observed after ceasing therapy. Hence, other therapeutic strategies should be evaluated in order to improve the sustained virological rate.

L'infection à cytomégalovirus (CMV) est la principale infection opportuniste après transplantation rénale. Malgré les stratégies préventives, il persiste des maladies à CMV, notamment chez les patients à haut risque (donneur séropositif/receveur séronégatif). Certains patients présentent des formes complexes avec des récurrences et des infections réfractaires et/ou résistantes aux antiviraux. La prévention de l'infection à CMV repose soit sur une prophylaxie universelle, soit sur une stratégie préemptive. Chez les patients à haut risque, la stratégie prophylactique est le plus souvent utilisée. Elle repose sur l'utilisation du valganciclovir, qui peut être responsable de leucopénies et de neutropénies sévères. Un nouvel antiviral, le létermovir, qui n'est pas encore disponible sur le marché en France dans cette indication, a montré une efficacité similaire au valganciclovir avec peu d'effets secondaires hématologiques. Des études récentes suggèrent l'intérêt de l'immuno-surveillance par ELISPOT ou Quantiféron pour guider la durée de la prophylaxie. D'autres études suggèrent également la possibilité de se passer d'un traitement prophylactique anti-CMV chez des transplantés rénaux CMV-séropositifs recevant des inhibiteurs de la mTOR. Le CMV réfractaire est défini par une absence de baisse de la charge virale d'au moins 1 log10 après deux semaines de traitement efficace. En cas d'absence de baisse de la charge virale, une recherche de mutations de résistance aux antiviraux doit être effectuée. Actuellement, le maribavir constitue le traitement de référence pour les formes réfractaires et résistantes. La clairance virale à la fin du traitement, ou huit semaines plus tard, est significativement supérieure à celle observée avec les autres antiviraux tels que le ganciclovir donné à forte dose, le foscarnet, ou le cidofovir. Cependant, le taux de rechute à l'arrêt du traitement par maribavir reste important. D'autres stratégies thérapeutiques doivent être évaluées pour améliorer ce taux de réponse virologique soutenue.

Treatment outcomes in cytomegalovirus anterior uveitis.

This retrospective cohort study investigated patients with cytomegalovirus anterior uveitis (CMV AU) and compared treatment outcomes between regional and systemic antiviral therapies. Treatment modalities included topical (2% ganciclovir [GCV] eye drops or 0.2% GCV eye gel) and systemic (intravenous GCV or oral valganciclovir) groups. The comparison parameters included response rates, time to response, recurrence rates, time to recurrence, and complications. Forty-four patients (54.5% male) with a mean age of 56 ± 9.87 years were enrolled, with 31 eyes in the topical group and 13 eyes in the systemic group. The median response time was significantly slower in the topical group (63 days [IQR 28-112]) compared to the systemic group (28 days [IQR 24-59]) (p = 0.04). Treatment response rates were 87.1% (27/31) in the topical group and 100% (13/13) in the systemic group (p = 0.30), while recurrence rates were 37% (10/27) and 69.2% (9/13) (p = 0.056), with a median time to recurrence of 483 days [IQR 145-1388] and 392 days [IQR 203.5-1907.5] (p = 0.20), respectively. In conclusion, both topical and systemic GCV treatments demonstrated favorable outcomes for CMV AU. Systemic GCV showed rapid control of intraocular inflammation.

Combined Effect of Basic Antiherpetic Drugs with a New Inhibitor of the Terminase Complex of Herpes Simplex Virus Type 1 in Vero Cell Cultures.

Carriers of herpes simplex virus type 1 (HSV-1) account for more than 90% of the global population. Infection manifests itself in the formation of blisters and ulcers on the face or genitals and can cause blindness, encephalitis, and generalized infection. All first- and second-line modern antiherpetic drugs selectively inhibit viral DNA polymerase. The purine-benzoxazine conjugate LAS-131 ((S)-4-[6-(purin-6-yl)aminohexanoyl]-7,8-difluoro-3,4-dihydro-3-methyl-2H-[1,4]benzoxazine), which we have described earlier, uses the large subunit of the HSV-1 terminase complex as a biotarget and selectively inhibits HSV-1 reproduction in vitro. Basically new results were for the first time obtained to characterize the combined effect on human herpesvirus infection for LAS-131 used in combination with practically significant antiviral compounds, including the nucleoside analogs acyclovir (ACV), penciclovir (PCV), ganciclovir (GCV), brivudine (BVdU), iododeoxyuridine (IdU), and adenine arabinoside (Ara-A); the nucleoside phosphonate analog cidofovir (CDV); and the pyrophosphate analog foscarnet (FOS). A cytopathic effect (CPE) inhibition assay showed that the drug concentration that inhibited the virus-induced CPE by 50% decreased by a factor of 2 (an additive effect, FOS) or more (a synergistic effect; ACV, PCV, GCV, IdU, BVdU, Ara-A, and CDV) when the drugs were used in combination with LAS-131. Nonpermissive conditions for HSV-1 reproduction were thus created at lower drug concentrations, opening up new real possibilities to control human herpesvirus infection.

Acquired Cytomegalovirus Retinitis in Preterm Infant Hospitalized in the NICU: A Noteworthy Case Report.

BACKGROUND: Acquired human cytomegalovirus (CMV) is a noteworthy disease in infants. This case study will highlight the influence of early diagnosis of CMV retinitis (CMVR) on avoid visual impairment. CLINICAL FINDINGS: We describe a preterm female infant with a birth weight of 2060 gr that was admitted for tracheostomy placement due to hypoxic-ischemic encephalopathy. There were no signs of CMV infection or sepsis in laboratory results upon admission such as serology (IgG, IgM antibodies), Toxoplasma gondii , Rubella virus, Herpes simplex virus, CMVR and urine polymerase chain reaction (PCR). PRIMARY DIAGNOSIS: Incidentally, upon screening for retinopathy of prematurity, diffuse occlusive vasculitis was detected in the retinal image on the 112th day of life. INTERVENTION: Intravenous and intraocular ganciclovir were administered for 4 weeks. OUTCOMES: In the follow-up visit 6 weeks after discharge from the hospital, visual impairment was detected on both sides. PRACTICE RECOMMENDATIONS: This is a report of a case of acquired CMVR, a silent finding, as an uncommon complication in preterm neonates during the hospital stay. This diagnosis should be taken into consideration in preterm infants, since early diagnosis and treatment are crucial to avoid visual impairment.

Emerging shadows: HHV-8-associated encephalitis unveiled in a solid organ transplant recipient.

Human herpesviruses (HHVs) cause a wide variety of central nervous system (CNS) infections including meningitis and encephalitis. While HHV-8 is not typically associated with neurological diseases, several studies have indicated a relationship, such as secondary central nervous system (CNS) metastases and a few isolated cases of HHV-8 encephalitis in acquired immunodeficiency syndrome (HIV). However, it has not been previously linked to encephalitis in solid organ transplantation (SOT). This case presents the first-ever instance of HHV-8 encephalitis in a SOT recipient. Our case highlights the association of HHV-8-related diseases, such as post-transplant Kaposi's Sarcoma (KS), with encephalitis. The patient was diagnosed with KS before developing neurological symptoms and received a prompt clinical response through intravenous foscarnet and ganciclovir treatment for 14 days. It is important to note that HHV-8 is a rare cause of encephalitis, and diagnosis requires a high index of suspicion in the appropriate clinical context, allowing for the use of antiviral therapy. This case also underscores the importance of considering the possibility of HHV-8-related diseases in SOT recipients, as they are at risk of developing such infections.

Contribution of Adsorption and Hematocrit Levels to Ganciclovir Clearance in an in Vitro Continuous Hemodiafiltration Model.

Estimation of the continuous hemodiafiltration (CHDF) clearance (CLCHDF) of ganciclovir (GCV) is crucial for achieving efficient treatment outcomes. Here, we aimed to clarify the contribution of diafiltration, adsorption, and hematocrit level to the CLCHDF of GCV in an in vitro CHDF model using three membranes: polyacrylonitrile and sodium methallyl sulfonate copolymer coated with polyethylenimine (AN69ST); polymethylmethacrylate (PMMA); and polysulfone (PS). In vitro CHDF was performed with effluent flow rates (Qe) of 800, 1500, and 3000 mL/h. The initial GCV concentration was 10 µg/mL while that of human serum albumin (HSA) was 0 or 5 g/dL. The CLCHDF, diafiltration rates, and adsorption rates were calculated. The whole blood-to-plasma ratio (R) of GCV for a hematocrit of 0.1 to 0.5 was determined using blood samples with 0.5 to 100 µg/mL of GCV. The in vitro CHDF experiment using AN69ST, PMMA, and PS membranes showed that the total CLCHDF values were almost the same as the Qe and not influenced by the HSA concentration. The diafiltration rate exceeded 88.1 ± 2.8% while the adsorption rate was lower than 9.4 ± 9.4% in all conditions. The R value was 1.89 ± 0.11 and was similar at all hematocrit levels and GCV concentrations. In conclusion, diafiltration mainly contributes to the CLCHDF of GCV, rather than adsorption. Hematocrit levels might not affect the relationship between the plasma and blood CLCHDF of GCV, and the CLCHDF of GCV can be estimated from the Qe and R, at least in vitro.

Comparison of prophylaxis and preemptive strategy as cytomegalovirus prevention in liver transplant recipients.

OBJECTIVES: Prophylaxis (P) or pre-emptive strategy (PS) in high-risk liver transplant recipients (LTRs) are either recommended. We compared the results of each strategy. METHODS: Two groups of LTR transplanted during two consecutive periods were compared. Only cytomegalovirus (CMV)-mismatched LTR (Donor +/ Recipient -) were included. The primary endpoints were: the onset of polymerase chain reaction-based DNAemia and the proportion of patients with CMV disease. A number of episodes of CMV infection, antiviral therapy, ganciclovir resistance, infectious or immunological complications, cost of both strategies, and survival (1, 5, and 10 years) were also compared. RESULTS: Forty-eight and 60 patients were respectively included in the P and PS groups. Eighteen (38%) in the P group and 56 (93%) in the PS group had CMV DNAemia (p <.0001) with a similar CMV disease rate (16.7% and 15%). Duration of curative therapy was longer in the PS group: 91 days versus 16 (p <.0001). Acute rejection was less frequent (p = .04) and more patients experienced a ganciclovir-resistant CMV infection in the PS group (10% vs. 0, p = .03). The drug-associated cost of PS was higher (10 004 vs. 4804€) and the median number of rehospitalization days tended to be higher (6 vs. 4, p = .06). Survival at any time was similar. CONCLUSION: We reported more CMV DNAemias and ganciclovir-resistant CMV events with PS. The cost of the PS strategy was higher.

Targeted eradication of EBV-positive cancer cells by CRISPR/dCas9-mediated EBV reactivation in combination with ganciclovir.

Epstein-Barr virus (EBV) is a ubiquitous human tumor virus that establishes lifelong, persistent infections in B cells. The presence of EBV in cancer cells presents an opportunity to target these cells by reactivating the virus from latency. In this study, we developed a novel approach for EBV reactivation termed clustered regularly interspaced short palindromic repeats (CRISPR)/dCas9-mediated EBV reactivation (CMER) strategy. Using modified CRISPR-associated protein 9 (dCas9) fused with VP64, we designed 10 single guide RNAs (sgRNAs) to target and activate the EBV immediate-early gene promoter. In Akata Burkitt lymphoma cells, 9 out of 10 CMER sgRNAs effectively reactivated EBV. Among these, CMER sgRNA-5 triggered robust reactivation across various cell types, including lymphoma, gastric cancer, and nasopharyngeal carcinoma cells. Importantly, the combination of CMER and ganciclovir selectively eliminated EBV-positive cells, regardless of their cell origin. These findings indicate that targeted virus reactivation by CMER, combined with nucleoside analog therapy, holds promise for EBV-associated cancer treatment. IMPORTANCE: This study explores a novel strategy called clustered regularly interspaced short palindromic repeats (CRISPR)/dCas9-mediated Epstein-Barr virus (EBV) reactivation (CMER) to reactivate the Epstein-Barr virus in cancer cells. EBV is associated with various cancers, and reactivating EBV from latency offers a potential therapeutic strategy. We utilized an enzymatically inactive CRISPR-associated protein 9 (dCas9) fused with VP64 and designed 10 single guide RNAs to target the EBV immediate-early gene promoter. Nine of these sgRNAs effectively reactivated EBV in Burkitt lymphoma cells, with CMER sgRNA-5 demonstrating strong reactivation across different cancer cell types. Combining CMER with ganciclovir selectively eliminated EBV-positive cells, showing promise for EBV-associated cancer treatment.

"Minimally symptomatic" congenital cytomegalovirus infection: latest data and emerging concepts.

PURPOSE OF REVIEW: Universal and targeted screening of newborns for congenital cytomegalovirus (CMV) infection is increasing globally. Questions remain concerning the management of infants who have been identified with congenital CMV infection, especially those with "minimally symptomatic" or clinically inapparent infection. Our objective is to discuss current management of CMV-infected neonates with a focus on less affected infants with or without sensorineural hearing loss (SNHL). RECENT FINDINGS: Valganciclovir is being prescribed increasingly in neonates with congenital CMV infection for improvement in hearing outcomes through 2 years of age. Treatment initiated in the first month of age is recommended for clinically apparent disease. A recent study showed hearing improvement at 18-22 months of age when therapy was initiated at age 1-3 months in infants with clinically inapparent CMV infection and isolated SNHL. SUMMARY: Antiviral therapy with either ganciclovir or valganciclovir has shown moderate benefit in prevention of hearing deterioration among infants with clinically apparent CMV infection or isolated SNHL. Sustainability of benefit beyond 2 years of age remains unknown. At present, infants with clinically inapparent CMV infection (normal complete evaluation including hearing) should not receive antiviral therapy. All CMV-infected infants require close audiological and neurodevelopmental follow-up.

Cytomegalovirus infection and disease in systemic lupus erythematosus patients at a high-complexity hospital in southwestern Colombia.

Cytomegalovirus (CMV) infection and disease is a condition usually described in immunocompromised patients, but among them, those with connective tissue diseases are poorly represented. Here we present the clinical, laboratory characteristics, management and outcomes of systemic lupus erythematosus (SLE) patients who presented with a CMV infection/disease to a high complexity hospital in southwestern Colombia between 2011 and 2020. 16 SLE patients were found to have a CMV infection. SLE was predominantly characterized by renal involvement (10 patients; 62.50%), and 14 patients (87.5%) were receiving steroids previous to the CMV infection. The entire sample required hospital admission, mainly related to acute kidney injury, and nine patients were admitted to the intensive care unit (ICU). Gastrointestinal organ damage was the most common CMV disease manifestation. All patients received ganciclovir, five of them (31.25%) suffered from septic shock, and seven (43.75%) died. Age ≥38 years and the presence of septic shock at admission were correlated to the mortality outcome. To our knowledge, this is the first publication evaluating SLE patients with CMV infection/disease in a Colombian population.

Antiviral medications for preventing cytomegalovirus disease in solid organ transplant recipients.

BACKGROUND: The risk of cytomegalovirus (CMV) infection in solid organ transplant recipients has resulted in the frequent use of prophylaxis to prevent the clinical syndrome associated with CMV infection. This is an update of a review first published in 2005 and updated in 2008 and 2013. OBJECTIVES: To determine the benefits and harms of antiviral medications to prevent CMV disease and all-cause death in solid organ transplant recipients. SEARCH METHODS: We contacted the information specialist and searched the Cochrane Kidney and Transplant Register of Studies up to 5 February 2024 using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov. SELECTION CRITERIA: We included randomised controlled trials (RCTs) and quasi-RCTs comparing antiviral medications with placebo or no treatment, comparing different antiviral medications or different regimens of the same antiviral medications for CMV prophylaxis in recipients of any solid organ transplant. Studies examining pre-emptive therapy for CMV infection are studied in a separate review and were excluded from this review. DATA COLLECTION AND ANALYSIS: Two authors independently assessed study eligibility, risk of bias and extracted data. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes and mean difference (MD) and 95% CI for continuous outcomes. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. MAIN RESULTS: This 2024 update found four new studies, bringing the total number of included studies to 41 (5054 participants). The risk of bias was high or unclear across most studies, with a low risk of bias for sequence generation (12), allocation concealment (12), blinding (11) and selective outcome reporting (9) in fewer studies. There is high-certainty evidence that prophylaxis with aciclovir, ganciclovir or valaciclovir compared with placebo or no treatment is more effective in preventing CMV disease (19 studies: RR 0.42, 95% CI 0.34 to 0.52), all-cause death (17 studies: RR 0.63, 95% CI 0.43 to 0.92), and CMV infection (17 studies: RR 0.61, 95% CI 0.48 to 0.77). There is moderate-certainty evidence that prophylaxis probably reduces death from CMV disease (7 studies: RR 0.26, 95% CI 0.08 to 0.78). Prophylaxis reduces the risk of herpes simplex and herpes zoster disease, bacterial and protozoal infections but probably makes little to no difference to fungal infection, acute rejection or graft loss. No apparent differences in adverse events with aciclovir, ganciclovir or valaciclovir compared with placebo or no treatment were found. There is high certainty evidence that ganciclovir, when compared with aciclovir, is more effective in preventing CMV disease (7 studies: RR 0.37, 95% CI 0.23 to 0.60). There may be little to no difference in any outcome between valganciclovir and IV ganciclovir compared with oral ganciclovir (low certainty evidence). The efficacy and adverse effects of valganciclovir or ganciclovir were probably no different to valaciclovir in three studies (moderate certainty evidence). There is moderate certainty evidence that extended duration prophylaxis probably reduces the risk of CMV disease compared with three months of therapy (2 studies: RR 0.20, 95% CI 0.12 to 0.35), with probably little to no difference in rates of adverse events. Low certainty evidence suggests that 450 mg/day valganciclovir compared with 900 mg/day valganciclovir results in little to no difference in all-cause death, CMV infection, acute rejection, and graft loss (no information on adverse events). Maribavir may increase CMV infection compared with ganciclovir (1 study: RR 1.34, 95% CI: 1.10 to 1.65; moderate certainty evidence); however, little to no difference between the two treatments were found for CMV disease, all-cause death, acute rejection, and adverse events at six months (low certainty evidence). AUTHORS' CONCLUSIONS: Prophylaxis with antiviral medications reduces CMV disease and CMV-associated death, compared with placebo or no treatment, in solid organ transplant recipients. These data support the continued routine use of antiviral prophylaxis in CMV-positive recipients and CMV-negative recipients of CMV-positive organ transplants.

Cytomegalovirus colitis as intestinal obstruction in an immunocompetent adolescent: a case report and literature review.

BACKGROUND: Cytomegalovirus infection manifests varying clinical characteristics and severity in diverse populations with different immune statuses. The signs and symptoms of gastrointestinal involvement are nonspecific. Here, we present a case of cytomegalovirus colitis in an immunocompetent adolescent, which manifested as intestinal pseud-obstruction. CASE PRESENTATION: A 15-year-old man who had contracted novel coronavirus infection one month earlier was admitted to our hospital with fever, abdominal pain, and hematochezia. His abdomen was distended, and laboratory evaluation revealed a decrease in the blood count, an increase in inflammatory indicators and hepatic impairment. Imaging shows bowel wall thickening and dilatation of the colon. A diagnosis of intestinal infection combined with acute intestinal pseud-obstruction was made. Diarrhea persisted despite conservative treatment with empirical antibiotics. A colonoscopy was performed. Pathology confirmed cytomegalovirus infection. Ganciclovir therapy was initiated, and subsequent review showed a good recovery. CONCLUSIONS: The case was diagnosed as cytomegalovirus colitis. We reviewed the reports of 9 cases of bowel obstruction, including our own, and found that the majority of the adult patients were elderly with underlying disease. Clinical and endoscopic manifestations are typically nonspecific, and imaging shows typical signs of intestinal obstruction. The final diagnosis was confirmed by pathology. Most of them have a good prognosis. We suggest that cytomegalovirus colitis can also lead to intestinal obstruction and that viral reactivation in immunocompetent individuals may be associated with inflammatory conditions and viral coinfection, particularly with the novel coronavirus.

Congenital and Postnatal Cytomegalovirus: Case Series and State of the Science for Neonatal Providers.

Cytomegalovirus (CMV), a beta-herpes virus, is the most common viral infection in infants. Transmission may occur congenitally (cCMV) or postnatally (pCMV). Early detection and intervention are crucial in reducing morbidities, notable developmental delays, and sensorineural hearing loss. However, more than 90% of infants are asymptomatic at birth. Treatment involves intravenous ganciclovir or the oral prodrug, valganciclovir, drugs usually reserved for use with symptomatic infants because of the toxicity profile. Research currently supports standardized antenatal CMV screening and treatment of affected pregnant patients with hyperimmune globulin as well as vaccination against CMV in unaffected pregnant patients, although widespread adoption is lacking. Standardized postnatal CMV screening is a proven, cost-effective way to detect and diagnose CMV and optimize outcomes across the lifespan. This article presents a case series of cCMV and pCMV and a review of the state of science of CMV as well as promising scientific advances that are on the horizon.

Acute primary CMV infection complicated by pneumonitis and ITP in young immunocompetent woman in a regional Queensland Hospital.

We present the first published case of simultaneous pneumonitis and immune thrombocytopenic purpura secondary to primary cytomegalovirus (CMV) infection in an immunocompetent patient. Treatment with oral valganciclovir for 2 weeks successfully led to complete clinical recovery. CMV is traditionally associated with infection in immunocompromised patients and neonates; however, evidence of severe CMV infections in immunocompetent hosts is emerging. It is important to highlight the broad range of clinical presentations of CMV infections to prevent diagnostic delay and associated morbidity and expense.

Combination of ganciclovir and trifluridine prevents drug-resistance emergence in HSV-1.

Ocular herpes simplex virus 1 (HSV-1) infections can lead to visual impairment. Long-term acyclovir (ACV) prophylaxis reduces the frequency of recurrences but is associated with drug resistance. Novel therapies are needed to treat drug-resistant HSV-1 infections. Here, we describe the effects of trifluridine (TFT) in combination with ACV or ganciclovir (GCV) on HSV-1 replication and drug-resistance emergence. Wild-type HSV-1 was grown under increasing doses of one antiviral (ACV, GCV, or TFT) or combinations thereof (ACV + TFT or GCV + TFT). Virus cultures were analyzed by Sanger sequencing and deep sequencing of the UL23 [thymidine kinase (TK)] and UL30 [DNA polymerase (DP)] genes. The phenotypes of novel mutations were determined by cytopathic effect reduction assays. TFT showed overall additive anti-HSV-1 activity with ACV and GCV. Five passages under ACV, GCV, or TFT drug pressure gave rise to resistance mutations, primarily in the TK. ACV + TFT and GCV + TFT combinatory pressure induced mutations in the TK and DP. The DP mutations were mainly located in terminal regions, outside segments that typically carry resistance mutations. TK mutations (R163H, A167T, and M231I) conferring resistance to all three nucleoside analogs (ACV, TFT, and GCV) emerged under ACV, TFT, ACV + TFT pressure and under GCV + TFT pressure initiated from suboptimal drug concentrations. However, higher doses of GCV and TFT prevented drug resistance in the resistance selection experiments. In summary, we identified novel mutations conferring resistance to nucleoside analogs, including TFT, and proposed that GCV + TFT combination therapy may be an effective strategy to prevent the development of drug resistance.

The complete Kaposi sarcoma-associated herpesvirus genome induces early-onset, metastatic angiosarcoma in transgenic mice.

Kaposi sarcoma (KS) is the most common cancer in persons living with HIV. It is caused by KS-associated herpesvirus (KSHV). There exists no animal model for KS. Pronuclear injection of the 170,000-bp viral genome induces early-onset, aggressive angiosarcoma in transgenic mice. The tumors are histopathologically indistinguishable from human KS. As in human KS, all tumor cells express the viral latency-associated nuclear antigen (LANA). The tumors transcribe most viral genes, whereas endothelial cells in other organs only transcribe the viral latent genes. The tumor cells are of endothelial lineage and exhibit the same molecular pattern of pathway activation as KS, namely phosphatidylinositol 3-kinase (PI3K)/Akt/mTOR, interleukin-10 (IL-10), and vascular endothelial growth factor (VEGF). The KSHV-induced tumors are more aggressive than Ha-ras-induced angiosarcomas. Overall survival is increased by prophylactic ganciclovir. Thus, whole-virus KSHV-transgenic mice represent an accurate model for KS and open the door for the genetic dissection of KS pathogenesis and evaluation of therapies, including vaccines.