Vertical mother-to-infant transmission of herpes simplex virus 2 is correlated with tropism due to mutations in viral UL13.

Although neonates are commonly exposed to vaginal herpes simplex virus (HSV)-2, neonatal herpes is rare. Therefore, we analyzed paired infant and maternal HSV-2 isolates from two cases of mother-to-infant transmission to identify viral factors contributing to vertical transmission. Sixteen infant isolates with neonatal herpes and 27 genital isolates in their third trimester were included. The infant isolates were significantly more temperature-independent than the maternal isolates. Sequence comparison revealed viral UL13 protein kinase (UL13-PK) mutation in the infant isolates in both cases. In the expanded cohort, infant isolates (5/18) had significantly more UL13-PK mutations than genital isolates (1/29). Isolates within 8 days post-birth (3/4) had a significantly higher frequency of UL13-PK mutation than those after 9 days (2/14), suggesting a close association between UL13-PK mutations and vertical transmission. Elongation factor 1-delta was identified as a target of UL13-PK by proteomic analysis of UL13-PK-positive and -negative HepG2 cells. The mixed infant isolates with the intact and mutated UL13-PK conferred altered cell tropism, temperature independence adapting to fetal temperature, and better growth properties in Vero and hepatoblastoma HepG2 cells than in HSV-2 with intact and mutated UL13-PK alone, indicating that viral UL13-PK mutation is essential for vertical HSV-2 transmission.

Butein inhibits corticosterone-induced apoptosis of Neuro2A cells by maintaining MEK-ERK signaling.

Stress-induced overactivation of glucocorticoid signaling may contribute to mental illness by inducing neuronal death and dysfunction. We previously reported that pretreatment with the plant flavonoid butein inhibits corticosterone (CORT)-induced apoptosis of Neuro2A (N2A) cells. In the current study, we examined whether MEK-ERK and PI3K-AKT signaling pathways are involved in neuroprotection by butein. N2A cells were pre-incubated with serum-free DMEM containing 0.5 µM butein for 30 min, and then incubated with serum-free DMEM containing 0.5 µM butein, 50 µM CORT, 50 µM LY294002, or 50 µM PD98059 as indicated for 24 h. We subsequently performed the MTT assay and the western blot analysis. As expected, CORT considerably reduced N2A cell viability and increased relative expression of the apoptosis effector cleaved caspase-3, whereas pretreatment with butein blocked these cytotoxic effects. Treatment with CORT alone also decreased both AKT and ERK protein phosphorylation. Butein pretreatment had no effect on AKT phosphorylation, and only partially reversed the reduction in phosphorylated ERK. However, cotreatment with butein and the PI3K inhibitor LY294002 during CORT exposure enhanced ERK phosphorylation, whereas cotreatment with butein and the ERK phosphorylation/activation inhibitor PD98059 enhanced AKT phosphorylation, suggesting that MEK-ERK negatively regulates AKT phosphorylation. Moreover, the protective efficacy of butein was blocked by PD98059 cotreatment but not LY294002 cotreatment. These findings suggest that butein protects neurons against glucocorticoid-induced apoptosis by sustaining ERK phosphorylation and downstream signaling.

The Interferon-Inducible Human PLSCR1 Protein Is a Restriction Factor of Human Cytomegalovirus.

Human phospholipid scramblase 1 (PLSCR1) is strongly expressed in response to interferon (IFN) treatment and viral infection, and it has been suggested to play an important role in IFN-dependent antiviral responses. In this study, we showed that the levels of human cytomegalovirus (HCMV) plaque formation in OUMS-36T-3 (36T-3) cells with high basal expression of PLSCR1 were significantly lower than those in human embryonic lung (HEL) cells with low basal expression of PLSCR1. In addition, the levels of HCMV plaque formation and replication in PLSCR1-knockout (KO) 36T-3 cells were significantly higher than those in parental 36T-3 cells and were comparable to those in HEL cells. Furthermore, compared to that in PLSCR1-KO cells, the expression of HCMV major immediate early (MIE) proteins was repressed and/or delayed in parental 36T-3 cells after HCMV infection. We also showed that PLSCR1 expression decreased the levels of the cAMP-responsive element (CRE)-binding protein (CREB)•HCMV immediate early protein 2 (IE2) and CREB-binding protein (CBP)•IE2 complexes, which have been suggested to play important roles in the IE2-mediated transactivation of the viral early promoter through interactions with CREB, CBP, and IE2. Interestingly, PLSCR1 expression repressed CRE- and HCMV MIE promoter-regulated reporter gene activities. These observations reveal, for the first time, that PLSCR1 negatively regulates HCMV replication by repressing the transcription from viral MIE and early promoters, and that PLSCR1 expression may contribute to the IFN-mediated suppression of HCMV infection. IMPORTANCE Because several IFN-stimulated genes (ISGs) have been reported to suppress HCMV replication, HCMV replication is thought to be regulated by an IFN-mediated host defense mechanism, but the mechanism remains unclear. PLSCR1 expression is induced in response to viral infection and IFN treatment, and PLSCR1 has been reported to play an important role in IFN-dependent antiviral responses. Here, we demonstrate that HCMV plaque formation and major immediate early (MIE) gene expression are significantly increased in PLSCR1-KO human fibroblast cells. PLSCR1 reduces levels of the CREB•IE2 and CBP•IE2 complexes, which have been suggested to play important roles in HCMV replication through its interactions with CREB, CBP, and IE2. In addition, PLSCR1 expression represses transcription from the HCMV MIE promoter. Our results indicate that PLSCR1 plays important roles in the suppression of HCMV replication in the IFN-mediated host defense system.

Emergence of varicella-zoster virus resistance to acyclovir: epidemiology, prevention, and treatment.

Introduction: Acyclovir has led to the development of successful systemic therapy for herpes simplex virus and varicella-zoster virus (VZV) infection, and the use of valacyclovir and famciclovir has improved treatment. Additionally, the use of a helicase-primase (HP) inhibitor (HPI), amenamevir, is changing the treatment of herpes zoster (HZ).Area covered: VZV infection is prevented by vaccines and is treated with antiviral agents. Acyclovir and penciclovir are phosphorylated by viral thymidine kinase and work as chain terminators. Improvements in the management of immunocompromised patients have reduced severe and prolonged immunosuppression and chronic VZV infection with acyclovir-resistant mutants has become rarer. The HP is involved in the initial step of DNA synthesis and amenamevir has novel mechanisms of action, efficacy to acyclovir-resistant mutants, and pharmacokinetic characteristics. The literature search for PUBMED was conducted on 10 April 2020 and updated on 4 November 2020.Expert opinion: Amenamevir has been used to treat HZ in Japan. Although the number of patients with VZV infection will decrease owing to the use of vaccines, the addition of HPI will improve treatment and treatment options for resistant viruses. The clinical use of HPIs in addition to current nucleoside analogs opens a new era of antiherpes therapy.

Viral ribonucleotide reductase attenuates the anti-herpes activity of acyclovir in contrast to amenamevir.

Amenamevir is a helicase-primase inhibitor of herpes simplex virus (HSV) and varicella-zoster virus (VZV) and is used for the treatment of herpes zoster in Japan. The half maximal effective concentrations (EC50s) of acyclovir and sorivudine for VZV increased as the time of treatment was delayed from 6 to 18 h after infection, while those of amenamevir and foscarnet were not affected. Susceptibility of infected cells at 0 and 18 h after infection was examined with four anti-herpes drugs, and the fold increases in EC50 for acyclovir, sorivudine, amenamevir, and foscarnet were 13.1, 6.3, 1.3, and 1.0, respectively. The increase in the EC50s for acyclovir in the late phase of infection in VZV and HSV was abolished by hydroxyurea, a ribonucleotide reductase (RR) inhibitor. The common mechanism affecting antiviral activities of acyclovir to HSV and VZV was examined in HSV-infected cells. The amount of HSV DNA in cells treated with amenamevir at 10 x EC50 was similar at 0 and 12 h but less than that in cells treated with acyclovir at 10 x EC50. dGTP, produced through viral RR, peaked at 4 h and decreased thereafter as it was consumed by viral DNA synthesis. Because acyclovir and amenamevir inhibited viral DNA synthesis, thus making dGTP unnecessary, dGTP was significantly more abundant in the presence of acyclovir and amenamevir than in untreated, infected cells. Abundant dGTP supplied by RR may compete with acyclovir triphosphate and attenuate its antiviral activity. In contrast, abundant dGTP did not influence the inhibitory action of amenamevir on viral helicase-primase activity. ATP was significantly decreased at 12 h after infection and significantly more abundant in untreated infected cells compared to cells treated with acyclovir and amenamevir. The anti-herpetic activity of amenamevir was not affected by the replication cycle of VZV and HSV, indicating the suitability of amenamevir for the treatment of herpes zoster and suppressive therapy for genital herpes.

Protective effects of butein on corticosterone-induced cytotoxicity in Neuro2A cells.

A functional understanding of the relationship between glucocorticoids and neuronal apoptosis induced by the production of reactive oxygen species (ROS) may lead to a novel strategy for the treatment or prevention of depression. Previous reports suggest that butein, a type of flavonoids, may be a potent candidate against depression-related neuronal cell apoptosis caused by oxidative stress; however, the protective effects of butein on damaged corticosterone (CORT)-treated neuronal cells has not been elucidated. In the present study, we examined the protective effect of butein on CORT-induced cytotoxicity and neurite growth during cell differentiation of mouse neuroblastoma Neuro2A (N2A) cells. Moreover, the effect on cultured cells by high concentrations of butein was confirmed. Our results demonstrate that CORT treatment significantly decreases cell viability and induces cell death. CORT was suggested to induce apoptosis via mitochondrial dysfunction and caspase-3 activation; this apoptosis may be attributed to DNA damage by ROS generation, found in this study to be significantly inhibited by pretreatment with butein. We found that CORT produced significant growth suppression of retinoic acid-induced neurite outgrowth in N2A cells; however, butein significantly increased neurite length and induced dose-dependent apoptotic cytotoxicity in N2A cells. This study suggests that low concentration of butein can prevent CORT-induced cytotoxicity in N2A cells, and provides preliminary results supporting some of the beneficial roles of butein in neuroprotection.

Favipiravir, an anti-influenza drug against life-threatening RNA virus infections.

Favipiravir has been developed as an anti-influenza drug and licensed as an anti-influenza drug in Japan. Additionally, favipiravir is being stockpiled for 2 million people as a countermeasure for novel influenza strains. This drug functions as a chain terminator at the site of incorporation of the viral RNA and reduces the viral load. Favipiravir cures all mice in a lethal influenza infection model, while oseltamivir fails to cure the animals. Thus, favipiravir contributes to curing animals with lethal infection. In addition to influenza, favipiravir has a broad spectrum of anti-RNA virus activities in vitro and efficacies in animal models with lethal RNA viruses and has been used for treatment of human infection with life-threatening Ebola virus, Lassa virus, rabies, and severe fever with thrombocytopenia syndrome. The best feature of favipiravir as an antiviral agent is the apparent lack of generation of favipiravir-resistant viruses. Favipiravir alone maintains its therapeutic efficacy from the first to the last patient in an influenza pandemic or an epidemic lethal RNA virus infection. Favipiravir is expected to be an important therapeutic agent for severe influenza, the next pandemic influenza strain, and other severe RNA virus infections for which standard treatments are not available.

The anti-human cytomegalovirus drug tricin inhibits cyclin-dependent kinase 9.

4',5,7-trihydroxy-3',5'-dimethoxyflavone (tricin), derived from Sasa albo-marginata, has been reported to suppress significantly human cytomegalovirus (HCMV) replication in human embryonic lung (HEL) fibroblast cells. However, the target protein of tricin remains unclear. This study focused on the anti-HCMV activity of tricin in terms of its binding affinity to cyclin-dependent kinase 9 (CDK9). A molecular docking study predicted that tricin binds well to the ATP-binding site of CDK9. Experimental measurements then revealed that tricin inhibits the kinase activity of CDK9 and affects the phosphorylation of the carboxy-terminal domain of RNA polymerase II. Based on these results, we conclude that CDK9 is one of the target proteins of tricin. We also found that tricin possesses anti-HCMV activity with no cytotoxicity against HEL cells.

Tricin inhibits the CCL5 induction required for efficient growth of human cytomegalovirus.

Treatment of human embryonic lung fibroblast (HEL) cells with tricin (4', 5, 7-trihydroxy-3', 5'-dimethoxyflavone) following infection with human cytomegalovirus (HCMV) reportedly significantly suppresses HCMV replication. In the present work, the mechanisms for the anti-HCMV effects of tricin in HEL cells were examined. It was found that exposure of HEL cells to tricin inhibited HCMV replication, with concomitant decreases in amounts of transcripts of the CC chemokine RANTES (CCL5)-encoding gene and in expression of the CCL5 protein. It was also found that transcripts of HCMV immediate early 1 (IE1), and HCMV UL54 (encoding DNA polymerase) and replication of HCMV was significantly lower in CCL5 gene-knockdown cells. These results suggest that the anti-HCMV activity of tricin differs from that of ganciclovir and that CCL5 is one of the chemokines involved in HCMV replication. In addition, it is possible that chemokine CCL5 is one of the targets of tricin.

An in silico-designed flavone derivative, 6-fluoro-4'-hydroxy-3',5'-dimetoxyflavone, has a greater anti-human cytomegalovirus effect than ganciclovir in infected cells.

A novel type of antiviral agent for human cytomegalovirus (HCMV) is required, because the appearance of ganciclovir (GCV) resistant viruses has been reported. Tricin (4',5,7-trihydroxy-3',5'-dimethoxyflavone) has been shown to suppress significantly HCMV replication in human embryonic lung (HEL) fibroblast cells. Recently, we revealed that the action of tricin is different from that of GCV and cyclin-dependent kinase 9 (CDK9) is one of the target proteins of tricin. These results suggested that tricin is considered as a novel type of anti-HCMV agent. However, its anti-HCMV potency is not greater than that of GCV. This study tried to develop novel compounds with much greater anti-HCMV activity than GCV. We first made modifications to tricin by introducing fluorine atom, and then performed molecular docking simulations using the designed compounds and CDK9. The calculated binding energies showed that 6F-tricin (6-fluoro-4'-hydroxy-3',5'-dimetoxyflavone) binds to CDK9 much stronger than tricin. Based on these results, 6F-tricin was synthesized, and then its anti-HCMV effect was analyzed in HEL cell cultures. As a result, 6F-tricin strongly suppressed HCMV replication in a dose-dependent manner. The anti-HCMV activity with a 50% effective concentration (EC50) was 0.126 nM, corresponding to about 1/200 and 1/400 of EC50 of GCV (27.5 nM) and tricin (54.3 nM), respectively. Moreover, 6F-tricin had no cytotoxicity against HEL cells at concentrations up to 10 µM. We further performed detailed analysis on the amino acid contributions to the binding energies and found that the strong binding affinity for 6F-tricin to CDK9 is attributed to the specific binding orientation of 6F-tricin in the ATP-binding site. These results suggest that 6F-tricin is a promising candidate for anti-HCMV drug development.

Characterization of susceptibility variants of poliovirus grown in the presence of favipiravir.

BACKGROUND: T-705 (favipiravir) is a potent inhibitor of RNA-dependent RNA polymerases of influenza viruses and no favipiravir-resistant virus has been isolated. Poliovirus RNA polymerase has been well characterized and isolation of resistant virus was examined in poliovirus. METHODS: Susceptibility variants of poliovirus I (Sabin strain) were isolated during passages in the presence of favipiravir and characterized for their susceptibility and the sequence of RNA polymerase. RESULTS: Five variants with 0.47-1.88 times the 50% inhibitory concentration for plaque formation of the parent poliovirus had amino acid variations in the 3D gene of the RNA polymerase. The distribution of amino acid variations was not related to ribavirin resistance, and two amino acid variation sites were found near the finger domain. CONCLUSION: Favipiravir as a chain terminator would not be incorporated and replicate to cause lethal mutagenesis as a mutagen like ribavirin, and resistant mutants were not isolated. A high replication level would generate mutations leading to favipiravir resistance as ribavirin resistance was generated, but generated mutations would be lethal to the RNA polymerase function.

Inhibition of human cytomegalovirus replication by tricin is associated with depressed CCL2 expression.

We previously reported that treatment with tricin (4',5,7-trihydroxy-3',5'-dimethoxyflavone) after human cytomegalovirus (HCMV) infection significantly suppressed both infectious virion production and HCMV replication in human embryonic lung fibroblast (HEL) cells. Moreover, we recently demonstrated that HCMV infection can increase the expression of CC-motif ligand 2 (CCL2/MCP-1) and of CCR2, a CCL2-specific receptor, effects that can in turn enhance HCMV infection and replication. Hence, we here examined whether the CCL2-CCR2 axis is involved in the anti-HCMV effects of tricin in HEL cells. Tricin exposure yielded dose-dependent decreases in the accumulation of transcripts for the HCMV immediate early gene and the DNA polymerase gene in HCMV-infected cells, along with decreased production of infectious HCMV. Concomitantly, tricin caused dose-dependent attenuation of HCMV infection-induced up-regulation of expression of CCL2 and CCR2 mRNAs and of CCL2 protein. Moreover, CCL2 reversed tricin-mediated inhibition of HCMV virion production in a dose-dependent manner. Thus, tricin appears to exert anti-HCMV activity by depressing CCL2 expression.

Interaction of Immunoglobulin with Cytomegalovirus-Infected Cells.

Intravenous immunoglobulin (IVIG) is used to treat or prevent severe viral infection, especially cytomegalovirus (CMV) infections. IVIG was characterized to understand its interaction with CMV-infected cells. IVIG retarded CMV spread and reduced virus yields depending on the neutralizing (NT) antibody titer. Immediate early protein synthesis was reduced by IVIG in 3 to 15 h, and IVIG specifically reduced the ratio of 66/68k protein synthesis among immediate early proteins in an NT antibody-dependent manner between 4 and 8 h after infection, indicating that antigenic modulation of CMV-infected cells by IVIG reduced viral protein synthesis and virus production. The half-life of antibody bound to CMV-infected cells was 3.8 h. NT antibody titers to varicella-zoster virus (VZV) and CMV in IVIG were dose dependently absorbed by cells infected with VZV and CMV, respectively, but the antibody titers to CMV and VZV, respectively, were not affected. NT antibody in 0.3 mL of IVIG (15 mg) was specifically absorbed by 108 CMV-infected cells and 107 VZV-infected cells, suggesting that the NT antibody in IVIG might be inactivated by one-tenth of a similar volume of CMV-infected or VZV-infected cells. Various antiviral activities of IVIG may contribute to control and alleviation of CMV infection.

Herpes Zoster and Recurrent Herpes Zoster.

BACKGROUND: The incidence of recurrent herpes zoster (HZ) and the relationship between initial and recurrent HZ are not clear. METHODS: The Miyazaki Dermatologist Society has surveyed ~5000 patients with HZ annually since 1997. A questionnaire regarding HZ and its recurrence was completed by the dermatologists. RESULTS: A total of 34 877 patients with HZ were registered at 43 clinics between June 2009 and November 2015. Among 16 784 patients seen at 10 of the 43 clinics, 1076 patients (6.41%) experienced recurrence. Herpes zoster was more frequent in female than in male patients (5.27 vs 4.25 in 1000 person-years, P < .001), as was HZ recurrence (7.63% vs 4.73%, P < .001). Two and three recurrences were observed in 49 and 3 patients, respectively. Recurrence in the same dermatome was observed in 16.3% of patients, and more frequently this occurred in the left side (P = .027). The number of HZ-experienced persons increased with age, and one third of the population had experienced HZ by the age of 80. CONCLUSIONS: Recurrent HZ was observed in 6.41% of patients, with a higher incidence in women. Moreover, HZ experience reduced the HZ incidence to 31.7% of the incidence in the HZ-naive population.

Profile of anti-herpetic action of ASP2151 (amenamevir) as a helicase-primase inhibitor.

The antiherpetic drugs acyclovir (ACV, valaciclovir) and penciclovir (famciclovir) are phosphorylated by viral thymidine kinase and terminate DNA synthesis. ASP2151 (amenamevir) and foscavir (PFA) directly inhibit viral helicase-primase and DNA polymerase, respectively, and inhibit replication of herpes simplex virus (HSV) and varicella-zoster virus. ACV, ASP2151, and PFA all inhibit HSV with a different mechanism of action and as a consequence, the kinetics of viral DNA accumulation and progeny virus production differ. This study focused on how viral DNA synthesis and its related events in the replication cycle would influence anti-HSV action of ACV, ASP2151, and PFA. ASP2151 suppressed HSV replication more efficiently than ACV at 10 × 50% effective concentration of plaque formation (EC50), when treatments were started 0-24 h after infection. ASP2151 and PFA were more potent than ACV in suppressing viral DNA synthesis and infectious virus production when they were added up to 3 h following infection. The virus replicated in the presence of ACV was compared for the ratios of HSV DNA copy number to infectivity with that without ACV and infectivity of ACV-treated virus was less efficient than that without ACV-treatment. The EC50 of infected cells in the time course after infection was preserved in PFA, limited in ASP2151, and much increased for ACV, indicating that viral DNA synthesis had little effect on antiviral action of PFA and ASP2151 but reduced the susceptibility of ACV. ASP2151 showed a preferable profile as an anti-herpetic agent with a better pharmacokinetic profile than ACV.

Subclinical generation of acyclovir-resistant herpes simplex virus with mutation of homopolymeric guanosine strings during acyclovir therapy.

BACKGROUND: Suppressive therapy in patients with genital herpes has been used in Japan since 2006. Susceptibility and resistance of herpes simplex virus (HSV)-2 to acyclovir were examined in genital isolates from patients receiving suppressive therapy and compared with those from those naïve to acyclovir and receiving episodic treatment with acyclovir. OBJECTIVE: The aim of this study was to analyze the effect of acyclovir use on the susceptibility to acyclovir and analysis of the thymidine kinase gene by acyclovir treatment. METHODS: Genital HSV isolates were obtained from three patients groups. Susceptibility to acyclovir, the frequency of acyclovir-resistant clones and mutations in the thymidine kinase gene of acyclovir-resistant clones were determined. RESULTS: Susceptibility to ACV was significantly higher in isolates from patients receiving suppressive therapy than those naïve to acyclovir and receiving episodic treatment, but the frequencies of resistant clones were similar among the three groups. Mutation in guanosine homopolymeric strings (G-string mutation) was significantly more frequent in clones during episodic treatment and suppressive therapy than clones from patients naïve to ACV. The frequency of G-string mutation was significantly less frequent in isolates from patients naïve to ACV than those experienced ACV therapy. CONCLUSION: The frequency of acyclovir-resistant mutants was not increased by episodic and suppressive therapy, but exposure to acyclovir significantly generated G-string mutations, possibly induced by acyclovir. Acyclovir therapy had no substantial effects on the susceptibility of HSV-2 or frequency of resistant virus but did generate subclinical G-string mutants in patients' HSV-2.

Identification of ribonucleotide reductase mutation causing temperature-sensitivity of herpes simplex virus isolates from whitlow by deep sequencing.

Herpes simplex virus 2 caused a genital ulcer, and a secondary herpetic whitlow appeared during acyclovir therapy. The secondary and recurrent whitlow isolates were acyclovir-resistant and temperature-sensitive in contrast to a genital isolate. We identified the ribonucleotide reductase mutation responsible for temperature-sensitivity by deep-sequencing analysis.

Detection of cytomegalovirus in an immunocompetent adult presenting with acute retinal necrosis due to varicella-zoster virus: a case report.

BACKGROUND: To report a case of simultaneous detection of cytomegalovirus (CMV) in acute retinal necrosis (ARN) due to varicella-zoster virus (VZV) in an immunocompetent adult. METHODS: A 65-year-old healthy woman presented with necrotizing retinitis. Vitreous, tears, saliva, and swabs of the auricular and forehead skin areas were collected and tested by polymerase chain reaction analysis at various time points during the treatment period. RESULTS: VZV and CMV DNA were detected in the vitreous, tears, saliva, and skin. CMV was present in fewer copies than VZV in the vitreous. The retinal lesion clinically improved rapidly only by acyclovir. According to the clinical findings and the clinical responses to acyclovir, CMV seems not to cause ARN in this case. CONCLUSION: VZV and CMV DNA were detected in the vitreous of a patient with VZV ARN. CMV reactivation appeared to be asymptomatic.

Functional differences between antiviral activities of sulfonated and intact intravenous immunoglobulin preparations toward varicella-zoster virus and cytomegalovirus.

Intravenous immunoglobulin (IVIG) is used to treat severe viral infection, especially varicella-zoster virus (VZV) and cytomegalovirus (CMV) infections. The neutralization antibody titers of eleven IVIG preparations from four companies were examined using VZV and CMV with and without complement. The neutralizing antibody titers of intact IgG preparations were three to six times higher after addition of complement. The effectiveness of the sulfonated IgG preparation was not enhanced by complement, but desulfonated IgG regained enhanced neutralization activity with complement. Antibody-dependent cellular cytotoxicity (ADCC) toward VZV-infected cells was observed with both intact and sulfonated IVIG and guinea pig splenocytes, but ADCC toward CMV-infected cells was not, although NK cell activity toward cells infected with VZV or CMV was detected by splenocytes. Sulfonated IVIG had no complement-activated neutralization of VZV and CMV but retained ADCC toward VZV with less activity after dilution than with intact IVIG. Because sulfonated IVIG is converted to the intact form after intravenous administration, it would show complement-enhanced neutralization and ADCC activity similar to that of intact IVIG in vivo. In this study we showed the effects of intact and sulfonated IgG on the functional activity of IgG against VZV and CMV.