Congenital cytomegalovirus infection via a re-infected mother with original antigenic sin: A case report

Original antigen sin and COVID-19: implications for seasonal vaccination

INTRODUCTION

Original antigenic sin describes the phenomenon in which immunity against pathogens or antigens is shaped by the host's first exposure to a related pathogen or antigen.

AREAS COVERED

When primary immunity is boosted not by the homologous but by a cross-reacting vaccine, the newly formed antibodies may react better with the primary antigen than with the antigen actually eliciting the response. This form of immune imprinting, which has been observed with influenza, dengue, human immunodeficiency virus, and other pathogens, has profound implications for the approach to seasonal vaccination against a variety of diseases, including COVID-19.

EXPERT OPINION

Public health agencies and regulatory bodies have consistently recommended repeated vaccination every few months as a way to protect against COVID-19. However, the risks and benefits of this approach requires scrutiny given the concern for original antigenic sin in response to SARS-CoV-2. This manuscript examines what is known about immune imprinting and looks ahead to explore how this phenomenon may impact seasonal vaccination against emerging SARS-CoV-2 subvariants such as BA.4, BA.5, and BA.5.1, which have been associated increased transmissibility due to enhanced immune escape.

Characteristics and serology of pregnant women with cytomegalovirus immunoglobulin G seroconversion during pregnancy in Japan

OBJECTIVE

Investigate the characteristics and serology of pregnant women with cytomegalovirus (CMV) immunoglobulin (Ig)G seroconversion during pregnancy to understand the risk factors associated with primary CMV infection and the occurrence of fetal congenital CMV infection.

MATERIALS AND METHODS

We retrospectively studied 3202 pregnant women who were CMV IgG-negative in early pregnancy and were retested for IgG in late pregnancy. Characteristics were compared between participants with and without IgG seroconversion, and serological parameters were compared between participants with and without fetal congenital CMV infection.

RESULTS

Twenty-six participants showed CMV IgG seroconversion and fifteen showed fetal congenital CMV infection. Seroconversion rates were significantly higher in teens (5.0%) than in older women (20s: 0.8%; 30s and over: 0.6%) (p < 0.001). Titers of CMV IgM at IgG seroconversion were higher in women without (median 8.66) than with (median 6.54) congenital infection (p = 0.045). The congenital infection rate was high when IgM titers at IgG seroconversion were low (47.1% with 4.00-12.00 titers and 100% with 1.21-3.99 IgM titers) (p = 0.048).

CONCLUSIONS

Nulliparous pregnant teenagers have a high risk of CMV IgG seroconversion and the CMV IgM titer at IgG seroconversion may help predict the occurrence of fetal congenital CMV infection.