Improved diagnostic and multiplex RT-qPCR for detecting rubella viral RNA

Diagnostic Challenges in Detecting Rubella Viral RNA in Cases of Congenital Rubella Syndrome Using RT-PCR in the Era of Elimination

BACKGROUND

Confirming the detection of rubella virus (RUBV) genotypes is crucial for tracking the transmission and evolution of the virus, which is essential for eliminating rubella. Reverse transcription-polymerase chain reaction (RT-PCR) plays a crucial role in identifying the viral genotype, but it comes with various challenges from sample collection to data interpretation. The present study aimed to explore the complexities of confirming the detection of RUBV in patients with congenital rubella infection using RT-PCR, discussing potential pitfalls and optimization strategies.

METHODS

From July 2019 to December 2021, we isolated the RUBV from throat swabs, lens materials, and urine samples obtained from patients with serologically confirmed and clinically compatible congenital rubella syndrome (CRS). The case definition and final classification of CRS were adapted from the World Health Organization-recommended CRS surveillance standard. We utilized the RT-PCR assay to detect the presence of RUBV ribonucleic acid (RNA).

RESULTS

During the study period, 126 patients with suspected CRS underwent complete clinical and serological examinations. Of these, 30 patients were included, and 22 were laboratory-confirmed. Using RT-PCR, RUBV was detected in only 42.1% of the laboratory-confirmed group. Overall, the lens material showed the highest positivity for detecting RUBV RNA. No correlation was found between the cycle threshold values and patient age at viral RNA testing.

CONCLUSIONS

The present study underscores the critical need for a multifaceted approach for accurately diagnosing CRS, particularly in the context of rubella elimination efforts. RT-PCR testing can be particularly useful for diagnosing CRS in patients over 12 months of age. By addressing the challenges and building upon the insights gained from our research, healthcare systems can enhance CRS diagnosis, guide timely interventions and ultimately contribute to the global rubella.

Neutralization of Rubella Vaccine Virus and Immunodeficiency-Related Vaccine-Derived Rubella Viruses by Intravenous Immunoglobulins

The association between granulomas and vaccine-derived rubella virus (VDRV) in people with primary immunodeficiencies has raised concerns about the ability of immunoglobulin preparations to neutralize VDRVs. We investigated the capacity of immunoglobulin to neutralize rubella vaccine virus and 4 VDRV strains. As expected, the rubella vaccine virus itself was potently neutralized by immunoglobulin preparations, but the VDRV isolates from patients after intrahost evolution, 2-6 times less so. Diagnosis of immune deficiencies before possible live-virus vaccination is thus of critical importance, while immunoglobulin replacement therapy can be expected to provide protection from rubella virus infection.

Seroepidemiology study of rubella virus antibodies among neonates and pregnant women at hospitals in Henan province, China

Rubella virus infection can cause vertical transmission to the fetus during pregnancy. In China's Henan province, rubella surveillance needs to be well-established. In this research, a total of 1933 neonates and 2502 pregnant women were enrolled, and their sera for IgG and IgM antibodies against rubella were tested by chemiluminescence assay. Of 1933 neonates' sera tested, the seropositive of rubella IgG was 68.7%. The seroprevalence of rubella IgM in neonates was 0.4%. 30.9% of neonates had negative results for IgG and IgM antibodies. Two thousand five hundred and two pregnant women participated in the serosurvey, and 79.3% were rubella IgG positive. Rubella IgG seropositivity in pregnant women differed by age and number of births. 0.8% of the pregnant women had positive results for IgM against the rubella virus. The seronegative of rubella IgG and IgM antibodies in pregnant women was 19.8%. Due to the negative rubella-specific IgG antibody, many neonates remain at risk of rubella virus infection. Rubella virus continues to spread since some neonates and pregnant women with rubella-specific IgM antibody positive have been detected. Rubella vaccination may be introduced for childbearing-age women to increase immunity levels against rubella with periodic sero-surveillance.

Case report: Persistent shedding of a live vaccine-derived rubella virus in a young man with severe combined immunodeficiency and cutaneous granuloma

A young man with X-linked severe combined immunodeficiency developed a persistent vaccine-derived rubella virus (VDRV) infection, with the emergence of cutaneous granulomas more than fifteen years after receipt of two doses of measles-mumps-rubella (MMR) vaccine. Following nasopharyngeal swab (NP) collection, VDRV was detected by real-time polymerase chain reaction (RT-qPCR) and sequencing, and live, replication-competent VDRV was isolated in cell culture. To assess duration and intensity of viral shedding, sequential respiratory samples, one cerebrospinal fluid sample, and two urine samples were collected over 15 months, and VDRV RNA was detected in all samples by RT-qPCR. Live VDRV was cultured from nine of the eleven respiratory specimens and from one urine specimen. To our knowledge, this was the first reported instance of VDRV cultured from respiratory specimens or from urine. To assess potential transmission to close contacts, NP specimens and sera were collected from all household contacts, all of whom were immunocompetent and previously vaccinated with MMR. VDRV RNA was not detected in any NP swabs from the contacts, nor did serologic investigations suggest VDRV transmission to any contacts. This report highlights the need to understand the prevalence and duration of VDRV shedding in granuloma patients and to estimate the risk of VDRV transmission to immune and non-immune contacts.