Cytomegalovirus infection in liver-transplanted children

Table 1 Risk of cytomegalovirus disease after liver transplantation

Risk factors
CMV serostatus of recipient and donor	D+/R−
	D+/R+ and D−/R+
Viral burden (initial CMV viral load)	High CMV viral load
	Rate of viral load increasing
Immunosuppressive agents	Antibody to CD3-receptor: OKT3 or muromonab
	Basiliximab
	Corticosteroids
	Mycophenolate mofetil
	Calcineurin inhibitors: Tacrolimus, sirolimus, and cyclosporine
Recipient immunity	TLR2 gene mutation, mutation of mannose-binding lectin
	Upregulation of programmed death-1 receptors
Recipient underlying liver disease	Hepatoblastoma with pre-transplant chemotherapy
Other risk factors	Virus-to-virus interaction (HHV6, HCV, fungal infection), transfusion of non-leucocyte-depleted blood products, volume of blood loss, liver transplantation because of fulminant liver failure, older age, non-white race, female sex, CVVH after liver transplant, septic shock, renal insufficiency

CMV: Cytomegalovirus; CVVH: Continuous venovenous haemofiltration; D: Donor; HCV: Hepatitis C virus; HHV-6: Human herpes virus-6; R: Recipient; TLR2: Toll-like receptor 2.

Table 2 Cytomegalovirus assays and clinical use

Investigation	Sample	Uses	Properties
Cell culture
Traditional cell culture (human fibroblast cells)	Tissue or non-tissue (blood, urine, oral secretion) sample	Not widely available	Highly specific
Shell vial assay (centrifugation-amplification technique)			Can be tested for phenotypic susceptibility; Takes a long time (2 to 21 d), more rapid with the shell vial assay (16 h)
Histopathology of organ-specific tissues
Plain histological microscopy	Tissue sample	Gold standard for diagnosis of tissue-invasive CMV disease	Low sensitivity but very high specificity
Immunohistochemistry		Used for reference of endpoint of treatment of tissue-invasive CMV disease
Molecular diagnosis (detection of viral genome)
Plasma quantitative nucleic acid testing (plasma QNAT)	Blood (plasma or whole blood)	Used to detect CMV DNAemia with high sensitivity; used in diagnosis, surveillance to guide pre-emptive antiviral treatment, and therapeutic monitoring	Generally high sensitivity but less sensitivity in R+ patients
Tissue QNAT	Tissue sample	Need more clinical trial studies	Better specificity but a lack of studies
Real-time PCR	Blood	Alternative to conventional plasma QNAT	More rapid and precise
NASBA assay	Blood	Under study as an alternative to conventional quantitative antigenaemia as a guide for starting pre-emptive therapy	Increased sensitivity for detection of CMV viraemia
Direct viral pp65 antigen detection	Whole blood or plasma	Diagnosis of CMV infection by detecting antigenaemia; Quantitative result, can guide initiation of pre-emptive therapy	After the blood collection, the sample must be processed within 6 h; False-negatives in patients with neutropenia
Serological analysis (viral antibody detection)
CMV IgG antibody testing	Plasma	Diagnosis of CMV infection	Better sensitivity and specificity; also positive in past infection
CMV IgM antibody testing		Pre-transplant assessment for serostatus of the donor and the recipient	Low sensitivity and specificity for diagnosis
Viral cellular response detection
QuantiFERON-CMV assay: IFN-γ released measurement	Plasma	Prognostic marker for risk of developing CMV disease: a positive result is associated with a lower incidenceMonitoring during prophylaxis or pre-emptive therapy	High positive predictive value but low negative value

CMV: Cytomegalovirus; D: Donor; IFN-γ; Interferon-gamma; NASBA: Nucleic acid sequence-based amplification; QNAT: Quantitative nucleic acid testing; R: Recipient; PCR: Polymerase chain reaction; Ig: Immunoglobulin.

Table 3 Uses of available cytomegalovirus assays

Use	Assay
Diagnosis	CMV viral load by plasma QNAT; CMV viral load by real-time PCR assay; pp65 antigen testing; CMV IgG/IgM antibodies
Diagnosis of tissue-invasive CMV disease	Histopathology
Pre-transplant risk stratification	CMV IgG/IgM antibodies
Threshold for initiation of pre-emptive therapy	CMV viral load by plasma QNAT; Quantitative pp65 antigen measurement; NASBA assay
Monitoring or endpoint (prophylaxis, pre-emptive or treatment)	CMV viral load by plasma QNAT; QuantiFERON-CMV assay
Endpoint of treatment of tissue-invasive CMV disease	Histopathology
Prediction of developing CMV disease	QuantiFERON-CMV assay

CMV: Cytomegalovirus; Ig: Immunoglobulin; PCR: Polymerase chain reaction; QNAT: Quantitative nucleic acid testing.

Table 4 Summary of pre-emptive, prophylaxis and treatment of cytomegalovirus disease in post-liver transplant patients

Condition	Pre-emptive		Prophylaxis	Treatment
Monitoring and endpoint	Monitoring: Weekly or every 2 wk CBC, BUN, Cr, AST, and ALT for first month and then monthly; Monthly CMV QNAT for 12 mo. Endpoint: CMV QNAT for VL negative for two samples 2 wk apart		Monitoring: Weekly CMV QNAT. Endpoint: CMV QNAT for VL negative for two samples 2 wk apart	Monitoring: Weekly CBC, BUN, Cr; Weekly CMV QNAT. Endpoint: CMV syndrome: Clinical resolution; VL less than 200 IU/mL on 1-2 consecutive weeks; Tissue-invasive CMV disease: Clinical resolution; Histologic evidence
Cut-off for start medication	Reference	Verma et al[8,14]; Saitoh et al[13]; Martín-Gandul et al[77]; Atabani et al[58]; Griffiths et al[78]	-	Kotton et al[55]
	Values	Non-specific: VL 500 copies/mL; VL 650 copies/mL; pp65 Ag 5 per 50000 leucocytes. D+/R-: Plasma VL 1500 IU/mL. D+/R- and R+: Plasma VL 2275 IU/mL or 2500 copies/mL; Whole blood VL 2520 or 3000 copies/mL. R+: VL 3983 IU/mL	None (risk donor/recipient pair-based)	VL > 200 IU/mL for 2 consecutive weeks
Duration	Reference	Razonable et al[32,38;71]; Razonable[39]; Razonable and Humar[51]; Razonable and Hayden[56]; Razonable[79]; Pappo et al[72]; Ueno et al[73]; Kotton et al[55]	Kotton et al[55]	Kotton et al[55]
	Values	Non-specific: 14 d to 3 mo; Extended to 6 mo; Extended to 12 mo. High risk: 6 mo. Intermediate risk: 3 mo. Low risk (D-/R-): Clinical follow-up	D+/R-: 3-6 mo. Others: 3-4 mo or 2-4 wk with CMV surveillance	At least 2 wk
Drug/dose/route	First-line: Ganciclovir (5 mg/kg IV q 24 h); Valganciclovir (< 15 kg: 15 mg/kg/dose po once daily; > 15 kg: 500 mg/m2/dose po once daily); Maximum dose: 900 mg/dose once daily; Combined ganciclovir then valganciclovir		First-line: Ganciclovir (same dose as pre-emptive); Valganciclovir (same dose as pre-emptive)	First-line: Ganciclovir [5 mg/kg IV q 12 h (+/- with dose adjustment for renal function)]. Second-line (ganciclovir-induced leucopenia): Foscarnet [60 mg/kg IV q 8 h or 90 mg/kg IV q 12 h (+/- with dose adjustment for renal function)]; Cidofovir [5 mg/kg once weekly × 2 doses then every 2 wk (+/- with dose adjustment for renal function)]. For ganciclovir-resistant [Ganciclovir: 7.5-10 mg/kg IV q 12 h (+/- with dose adjustment for renal function). Add or switch to Foscarnet. Switch to Cidofovir

ALT: Alanine aminotransferase; AST: Aspartate aminotransferase; BUN: Blood urea nitrogen; CBC: Complete blood count; CMV: Cytomegalovirus; Cr: Creatinine; Ig: Immunoglobulin; QNAT: Quantitative nucleic acid testing; VL: Viral load; D: Donor; R: Recipient.