Salivary antibodies to cytomegalovirus (CMV) glycoprotein B accurately predict CMV infections among preschool children

IgA binds to the AD-2 epitope of glycoprotein B and neutralizes human cytomegalovirus

Human cytomegalovirus (HCMV) is a ubiquitous pathogen that is potentially pathogenic in immunosuppressed individuals and pregnant females during primary infection. The HCMV envelope glycoprotein B (gB) facilitates viral entry into all cell types and induces a potent immune response. AD-2 epitope is a highly conserved linear neutralizing epitope of gB and a critical target for antibodies; however, only 50% of sero-positive individuals make IgG antibodies to this site and IgA responses have not been fully investigated. This study aimed to compare IgG and IgA responses against gB and the AD-2 epitope in naturally exposed individuals and those receiving a recombinant gB/MF59 adjuvant vaccine. Thus, vaccination of sero-positive individuals improved pre-existing gB-specific IgA and IgG levels and induced de novo gB-specific IgA and IgG responses in sero-negative recipients. Pre-existing AD-2 IgG and IgA responses were boosted with vaccination, but de novo AD-2 responses were not detected. Naturally exposed individuals had dominant IgG responses towards gB and AD-2 compared with weaker and variable IgA responses, although a significant IgA binding response to AD-2 was observed within human breastmilk samples. All antibodies binding AD-2 contained kappa light chains, whereas balanced kappa/lambda light chain usage was found for those binding to gB. V region-matched AD-2-specific recombinant IgG and IgA bound both to gB and to AD-2 and neutralized HCMV infection in vitro. Overall, these results indicate that although human IgG responses dominate, IgA class antibodies against AD-2 are a significant component of human milk, which may function to protect neonates from HCMV.

Non-invasive detection of IgG antibodies from common pathogenic viruses using oral flocked swabs

Salivary antibodies are useful in surveillance and vaccination studies. However, low antibody levels and degradation by endonucleases are problematic. Oral flocked swabs are a potential non-invasive alternative for detecting viral antibodies. Seroprevalence for Cytomegalovirus (CMV), Varicella-Zoster virus (VZV), Epstein-Barr virus (EBV), Measles and Mumps IgG antibodies were determined from 50 matched serum, saliva and swabs samples from healthy volunteers using commercial ELISAs. CMV IgG, VZV IgG, and EBV EBNA-1 IgG, VCA IgG, and Measles IgG swab versus serum sensitivities were 95.8%, 96.0%, 92.1%, 95.5%, 84.5%, respectively, and swabs correlated well with saliva. Sensitivity of Mumps IgG in swabs and saliva was poor at 60.5%, and 68.2%, respectively. Specificities for IgG antibodies were 100% for CMV, EBV and Mumps, but could not be determined for VZV and Measles due to exclusively seropositive volunteers. Except for Mumps IgG, swabs correlate well with serum, are easy to self-collect and are stable at room temperature.

Prevalence of CMV infection among sexually active adolescents: a matched case-control study

Background

We observed previously that African American adolescents in Richmond reporting infrequent sexual activity had cytomegalovirus (CMV) seroprevalence rates one half that of their adult mothers and caregivers. We therefore sought to determine if sexually active African American adolescents have higher rates of CMV infection than sexually inactive African American adolescents.

Methods

Cases (aged 13–18 years) sought care for a sexually transmitted infection (STI) or pregnancy. Controls were sexually inactive and matched to cases for age, race, and gender and enrolled at the same clinic as cases and sought medical treatment unrelated to an STI. Subjects completed a questionnaire, provided saliva for antibody testing, and were interviewed for determination of sexual activity.

Results

Two groups of sexually active cases were enrolled. The first group had a diagnosis of an STI. In this group, both cases and matched controls were seropositive at a rate of 32% (7/22 for cases and 7/22 for controls). In the second group, cases self-reported an STI but objective evidence was lacking. In this group, cases were seropositive at a rate of 38% (six of 16) compared with matched controls among whom 6.3% were seropositive (one in 16). The overall rate of seropositivity in all 38 cases was 34% compared with a rate of 21% for all controls (P=0.3, odds ratio 2.0, 95% confidence interval 0.6–7.5).

Conclusion

Our results confirm lower rates of CMV infection among the current generation of African American adolescents compared with African American adults in Richmond, and suggest that this is not associated with sexual activity.

Neutralizing activity of saliva against cytomegalovirus

Congenital cytomegalovirus (CMV) disease is the leading cause of permanent disability in neonates in the United States. Neutralizing antibodies in saliva may protect against maternal CMV infection by blocking viral entry into oral epithelial cells, but the antibody response to CMV in the saliva following natural infection is not well characterized. Saliva specimens from naturally infected individuals were tested for CMV-neutralizing activity using epithelial and fibroblast cells. Saliva from seronegative adults had no inherent anti-CMV activity. Neutralizing activity of saliva from naturally infected adults was not detectable using fibroblast cells, and saliva from young children, adolescents, and Towne vaccine recipients did not have activity using either cell type. However, when using epithelial cells, neutralizing activity was present in saliva from 50% of seropositive adults, correlated with serum-neutralizing activity, and was more prevalent in mothers of children in day care than in non-day care-associated adults. Three day care mothers with high salivary neutralizing activities (>1:20) had exceptionally high serum-neutralizing titers (3- to 8-fold higher than typical seropositives) and were immunoblot positive for serum antibodies to the epithelial entry mediator UL130. These results suggest that salivary neutralizing activities are attainable by induction of high serum IgG levels and could be utilized to evaluate candidate cytomegalovirus vaccines.

Human Cytomegalovirus Infection Among Patients Living With AIDS in a Tertiary Level Hospital in India

Objective: Detecting the prevalence of human cytomegalovirus (CMV) coinfection in HIV-infected individuals attending a tertiary care hospital in Delhi by using 3 laboratory tests namely pp65 antigenemia assay, CMV DNA polymerase chain reaction (PCR), and immunoglobulin M (IgM) enzyme-linked immunosorbent assay (ELISA) for anti-CMV antibody. Design: HIV seropositive patients with CD4 count ≤100 cells/mm3 were included as cases and HIV-negative healthy individuals as controls. Blood samples were collected from all participants and 3 tests were performed. Methods: pp65 antigenemia assay and IgM ELISA were performed by commercially available kits; PCR was performed by an in-house nested PCR method. Results: In all, 7.1%, 5.7%, and 2.9% were positive for pp65 antigenemia, CMV DNA, and IgM antibody against CMV, respectively. On the basis of pp65 and/or PCR positivity, it can be said that active CMV coinfection was present in 8.57% of the cases. Conclusion: In the post-antiretroviral therapy (ART) era, CMV coinfection in HIV-infected patients has significantly declined.

The frequency of pregnancy and exposure to cytomegalovirus infections among women with a young child in day care

OBJECTIVE

The purpose of this study was to determine the frequency of pregnancy and exposure to cytomegalovirus (CMV) among mothers contemplating a possible additional pregnancy and with a child less than 2 years of age in group day care.

STUDY DESIGN

We performed a prospective observational study that included a demographic questionnaire and serologic and virologic monitoring of mothers and their children in day care.

RESULTS

Of 60 women, 62% were seronegative and 20% had a child shedding CMV. Of the 60 women, 23 women or 38% (95% CI, 0.27-0.51) became pregnant on average 10 months after enrollment. During pregnancy, 8 or 35% (95% CI, 0.19-0.55) of these pregnant women had a child in day care who shed CMV.

CONCLUSION

These results illustrate the potential magnitude of the public problem associated with exposure to a silent viral infection during pregnancy. Our data, when extrapolated to the US population, estimate that every 2 years between 31,000 and 168,000 susceptible pregnant women will be exposed to CMV by an infected child.

Cytomegalovirus infections among African-Americans

Background

Since African-Americans have twice the prevalence of cytomegalovirus (CMV) infections as age-matched Caucasians we sought to determine the ages and possible sources of infection of African-American children.

Methods

Subjects were 157 African-American healthy children and adolescents and their 113 household adults in Richmond VA. Families completed a questionnaire, provided saliva for antibody testing, and adolescents were interviewed regarding sexual activity.

Results

Regardless of age CMV seropositivity was not associated with gender, breast feeding, health insurance, sexual activity, or household income, education, or size. In the final regression model, prior CMV infection in adults was over two-fold higher than in children (chi-square = 18.8, p < 0.0001). At one year of age the CMV seropositivity rate was 11% (95%CI = 4% – 24%) and increased 1.8% each year until age 13 years. Between ages 13 and 20 years the CMV seropositivity rate remained between 22% and 33%. For adults, the CMV seropositivity rate was 84% in 21 year olds (95%CI = 69%–.92%). There was no association between CMV infections of the children and their mothers but CMV infections among siblings were associated.

Conclusion

We observed that African-American children had CMV seroprevalence rates by age 20 years at less than one-half of that of their adult mothers and caregivers. Sibling-to-sibling transmission was a likely source of CMV infections for the children. The next generation of African-American women may be highly susceptible to a primary CMV infection during pregnancy and may benefit from a CMV vaccine.

Cytomegalovirus antibodies in tear fluid of patients with retinitis

The diagnosis of cytomegalovirus retinitis (CMV-R) is difficult and usually based on clinical criteria or invasive diagnostic procedures. The purpose of this study was to investigate a possible association between CMV-R and specific anti-CMV antibodies in tears. Paired tear and serum samples were obtained from 96 individuals, which included 20 children with congenital CMV infection and chorioretinitis, 56 adults with retinitis with clinical signs suggestive of viral infection, and 20 healthy control subjects, and were tested for CMV antibodies using ELISA. The prevalence of anti-CMV antibodies in tears was found to be 80% (16/20) in children, 35% (20/56) in adults, and 5% (1/20) in control subjects. Furthermore, high antibody levels were detected in 35% (7/20) of children and 10.7% (6/56) of adults with retinitis, and were not found in control subjects. There was a strong association between high tear levels of anti-CMV antibodies and active ocular infection. No correlations were found between tear and serum antibodies. ELISA sensitivity was 80% and specificity 95%. Further studies are needed to compare the tear and intraocular levels of CMV-specific antibodies in patients with retinitis to find out if CMV antibody testing in tear fluid could substitute for more invasive diagnostic procedures.

Epidemiology of herpes simplex virus in children by detection of specific antibodies in saliva

OBJECTIVES

To facilitate the study of the prevalence of herpes simplex virus (HSV) infection and its determinants in children, we developed a noninvasive saliva test.

METHODS

A capture enzyme-linked immunosorbent assay (ELISA) for the detection of IgG to HSV in saliva was developed, validated against a commercial serum ELISA in 110 children and 187 adults and used in a cross-sectional population-based study including 2,048 children ages 1 to 17 years, recruited in day-care centers and schools of Geneva, Switzerland. Demographic and socioeconomic determinants of HSV prevalence were studied.

RESULTS

The sensitivity and specificity of the saliva assay were 94.1 and 95.5%, respectively, compared with the commercial serum ELISA. Participation in the cross-sectional study was 86.6%. The overall prevalence of anti-HSV IgG was 23.91%. It increased with age up to 7 years, reaching a plateau at 35% without evidence for day-care or school transmission. The main determinants of prevalence were region of national origin and parents' professional category.

CONCLUSIONS

This new saliva-based assay proved its feasibility in the first population-based study of HSV prevalence in children that uses saliva, confirmed its validity by identifying determinants of prevalence consistent with previous reports and yielded new information, such as the lack of influence of day-care attendance, in the population studied.

Safety and immunogenicity of the Towne strain cytomegalovirus vaccine

BACKGROUND

Women with naturally acquired serum antibodies to cytomegalovirus (CMV) are usually protected against both frequent secondary infection and giving birth to infants severely affected by intrauterine CMV infection.

OBJECTIVE

To determine the feasibility of using a live attenuated strain of CMV (Towne) to achieve immunity similar to that provided by wild-type infection, we evaluated a new lot of the Towne strain of CMV in 3 open label trials involving 68 men, 63 women of childbearing age and 13 children, respectively.

RESULTS

Mild local reactions occurred among approximately one-third of subjects. There were no systemic reactions. All 45 subjects tested developed lymphoproliferative responses to CMV. CD8+ class I-restricted cytotoxic T cell responses specific for CMV antigens were detected in three of four subjects and persisted for 6 months. Neutralizing titers were maximal at 2 to 4 months postimmunization, were dose-dependent and were comparable to those induced by natural infection.

CONCLUSION

These results support further evaluation of the Towne strain of CMV in women at risk for acquiring CMV infection during pregnancy or among children transmitting CMV to pregnant women.