Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2019 Jun 25;116(26):13036-13041.
doi: 10.1073/pnas.1903317116. Epub 2019 Jun 12.

Neutralization of rhesus cytomegalovirus IL-10 reduces horizontal transmission and alters long-term immunity

Jesse D Deere  1 , W L William Chang  2 , Andradi Villalobos  2 , Kimberli A Schmidt  2 , Ashlesha Deshpande  3 , Luis D Castillo  2 , Joseph Fike  2 , Mark R Walter  3 , Peter A Barry  4 , Dennis J Hartigan-O'Connor  5
Affiliations

Neutralization of rhesus cytomegalovirus IL-10 reduces horizontal transmission and alters long-term immunity

Jesse D Deere et al. Proc Natl Acad Sci U S A. .

Abstract

Human cytomegalovirus (HCMV) causes severe disease in infants and immunocompromised people. There is no approved HCMV vaccine, and vaccine development strategies are complicated by evidence of both persistent infection and reinfection of people with prior immunity. The greatest emphasis has been placed on reducing transmission to seronegative pregnant women to prevent vertical transmission and its potentially severe sequelae. Increasing evidence suggests that the earliest host-HCMV interactions establish conditions for viral persistence, including evasion of host immune responses to the virus. Using a nonhuman primate model of HCMV infection, we show that rhesus macaques immunized against viral interleukin-10 (IL-10) manifest delayed rhesus cytomegalovirus (RhCMV) acquisition and altered immune responses to the infection when it does occur. Among animals with the greatest antiviral IL-10-neutralizing activity, the timing of RhCMV seroconversion was delayed by an average of 12 weeks. After acquisition, such animals displayed an antibody response to the new infection, which peaked as expected after 2 weeks but then declined rapidly. In contrast, surprisingly, vaccination with glycoprotein B (gB) protein had no discernible impact on these outcomes. Our results demonstrate that viral IL-10 is a key regulator of successful host immune responses to RhCMV. Viral IL-10 is, therefore, an important target for vaccine strategies against cytomegalovirus (CMV). Furthermore, given the immunoregulatory function of viral IL-10, targeting this protein may prove synergistic with other vaccine therapies and targets. Our study also provides additional evidence that the earliest host-CMV interactions can have a significant impact on the nature of persistent infection.

Keywords: IL-10; cytomegalovirus; rhesus cytomegalovirus; vaccine; viral IL-10.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Fig. 1.
Fig. 1.
Vaccination with recombinant gB, vIL-10, or both proteins elicited binding and neutralizing antibody responses. (A) Experimental design and timeline. Three groups of five RhCMV-uninfected macaques were immunized three times with modified recombinant vIL-10, modified recombinant gB, or both. (B) Neutralizing antibody responses to recombinant vIL-10 were assessed in macaques vaccinated with either vIL-10 alone or with both vIL-10 and gB. The assay was completed in duplicate. (C) Plasma samples were assessed for RhCMV-neutralizing antibody responses using a cell culture-based assay. NT50 antibody titers are shown. A panel of macaques chronically infected with RhCMV (CI; dark blue inverted triangles) from the CNPRC was identified by ELISA. These animals were also assessed for RhCMV-neutralizing antibodies; n = 5 for each vaccine treatment group, and n = 26 for the CI group. Symbols indicate individual macaques, the boxes indicate the group mean, and the error bars display SEM of the assay completed in triplicate. (D) Plasma samples were assessed for RhCMV binding antibodies to the vaccine strain by ELISA. The assay was completed in duplicate, and the lines display the median A450 for each group.
Fig. 2.
Fig. 2.
Analysis of RhCMV UCD52 transmission. (A and B) Four unvaccinated macaques, cohoused with the vaccinated macaques, were inoculated with RhCMV UCD52 at week 0. (A) Plasma samples from the inoculated macaques were analyzed by ELISA in duplicate for UCD52 to determine seroconversion. (B) RhCMV shedding in saliva in the inoculated macaques was monitored by qPCR analysis for RhCMV DNA in triplicate. Symbols and thin lines indicate individual macaques, the black lines display the group average, and the dashed lines indicate either (A) the cutoff value for ELISA seroconversion or (B) the limit of detection for qPCR analysis. (C) Survival plot for vaccinated macaques displaying the rates of seroconversion to RhCMV pp65, a nonvaccine antigen. Binding antibodies were measured in plasma by ELISA and used to determine rates of horizontal transmission. The assays were completed in duplicate. (D) RhCMV DNA was quantified in plasma samples by qPCR in triplicate reactions to assess systemic viral replication and dissemination. The bars display the average virus load post-RhCMV seroconversion or the mean peak viremia for each group, and the error bars display SEM. (E) RhCMV DNA was measured in oral swabs by qPCR in triplicate to quantify viral shedding in saliva. The bars display the average virus titers in saliva post-RhCMV seroconversion or the mean peak viremia for each group, and the error bars display SEM.
Fig. 3.
Fig. 3.
Horizontal transmission of RhCMV was compared between vaccinees that developed strong vaccine-induced vIL-10–neutralizing antibody responses (blue; n = 5) and those that developed only weak vIL-10–neutralizing antibody responses from vaccination (green; n = 5). (A) RhCMV pp65 seroconversion was compared between the two groups of responders in a survival plot. The results of a Cox regression analysis are displayed. The control unvaccinated animals are not included in this analysis, because two did not seroconvert. The impact of these responses on viremia (B) and viral shedding in saliva (C) postseroconversion was assessed by analyzing samples longitudinally by qPCR for RhCMV DNA. Box and whisker plots display the results: the horizontal lines indicate the median, the + symbols indicate the average, the boxes indicate the interquartile range, and the stems represent 1.5 times the value of this range. Scatterplots compare the average AUCs throughout the study with vaccine-mediated vIL-10–neutralizing antibody responses. Linear regression analysis for each plot is also displayed (solid black lines). The dashed lines indicate the limit of detection by qPCR.
Fig. 4.
Fig. 4.
Systemic binding antibody responses to total RhCMV UCD52 antigen were compared between macaques that manifested strong vaccine-induced vIL-10–neutralizing antibody responses (blue; n = 4) and those that developed only weak responses (green; n = 5). (A) Longitudinal analyses of UCD52 antibody responses in plasma during the challenge phase of the study were analyzed by ELISA in duplicate. Thin lines display individual macaques within each group, while the bold lines represent mean responses. (B) The slope of the line representing UCD52 binding antibody responses over the final 6 wk of the study (weeks 34–40) was determined for each macaque and compared using a scatterplot. A correlation analysis demonstrated that increased strength of vIL-10–neutralizing antibody responses was associated with a greater decline in RhCMV binding antibody responses. The points represent individual macaques, and the solid line displays a linear regression analysis trendline. (C) Peak and terminal (week 40) RhCMV UCD52 antibody responses in strong and weak vIL-10 vaccine responders were compared. The boxplots with Tukey analysis display the group medians (horizontal lines), the group averages (+ symbols), the interquartile ranges (boxes), and 1.5 times the value of the ranges (stems). The results of t tests comparing these responses are also displayed. **P = 0.0006; ***P = 0.0002; ****P < 0.0001.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Cannon M. J., Hyde T. B., Schmid D. S., Review of cytomegalovirus shedding in bodily fluids and relevance to congenital cytomegalovirus infection. Rev. Med. Virol. 21, 240–255 (2011). - PMC - PubMed
    1. Hertel L., Human cytomegalovirus tropism for mucosal myeloid dendritic cells. Rev. Med. Virol. 24, 379–395 (2014). - PMC - PubMed
    1. Arvin A. M., Fast P., Myers M., Plotkin S., Rabinovich R.; National Vaccine Advisory Committee , Vaccine development to prevent cytomegalovirus disease: Report from the National Vaccine Advisory Committee. Clin. Infect. Dis. 39, 233–239 (2004). - PubMed
    1. Crough T., Khanna R., Immunobiology of human cytomegalovirus: From bench to bedside. Clin. Microbiol. Rev. 22, 76–98 (2009). - PMC - PubMed
    1. Griffiths P. D., Burden of disease associated with human cytomegalovirus and prospects for elimination by universal immunisation. Lancet Infect. Dis. 12, 790–798 (2012). - PubMed

Publication types

MeSH terms