Serologic Cross-Reactivity between the Mumps Virus Vaccine Genotype A Strain and the Circulating Genotype G Strain.

Recent mumps outbreaks have been observed in vaccinated young adults due to the mumps virus (MuV) of genotype G, whereas the current vaccine is a mixture of two genotype A strains. These outbreaks could be attributed to waning vaccine immunity or the antigenic differences between the HN and F glycoproteins in the vaccine and circulating MuV. These glycoproteins are essential targets for the immune system, and antigenic variations may reduce the recognition of mumps antibodies, rendering the population susceptible to the MuV.

Population immunity to varicella in Canada: A Canadian Immunization Research Network (CIRN) study.

Introduction: The incidence of varicella in Canada has decreased by almost 99% since vaccination was introduced. However, variation in the timing and eligibility of vaccination programs across the country has resulted in some cohorts being under-vaccinated and therefore potentially susceptible to infection.

Methods: We used nationally representative specimens from the Biobank of Statistics Canada's Canadian Health Measures Survey (CHMS) as well as residual specimens from Ontario collected between 2009-2014 to estimate population immunity across age-groups and geography, and identify any groups at increased risk of varicella infection.

Maternal varicella antibodies in children aged less than one year: Assessment of antibody decay.

Objectives: To investigate maternal antibody levels to varicella in infants <12 months of age in Ontario, Canada.

Study Design: In this study, we included specimens from infants <12 months of age, born at ≥37 weeks gestational age, who had sera collected at The Hospital for Sick Children (Toronto, Canada) between 2014-2016. We tested sera using a glycoprotein-based enzyme-linked immunosorbent assay (gpELISA).

Uptake of pertussis immunization in pregnancy and determinants of vaccination in Toronto, Canada.

Introduction: Pertussis causes significant morbidity and mortality in infants aged <6 months. Maternal pertussis vaccination during pregnancy has been recommended in Canada since 2018 to reduce these negative outcomes. In the absence of routine immunization coverage data, our objective was to evaluate uptake in Toronto, Canada.

Epidemiology of cytomegalovirus antiviral resistance testing for solid organ and bone marrow transplant patients from 2011 - 2019.

Background: CMV reactivation post-transplantation is common, with need for prompt identification of patients most at-risk for CMV antiviral drug resistance (AVDR).

Objectives: This study describes CMV AVDR frequencies, antiviral prescribing practices, and AVDR risk factors in patients from 2011 to 2019 in British Columbia, Canada.

Study Design: Retrospective review of demographics, transplant type, viral loads, antiviral exposure duration, and 12-month mortality was conducted for all patients with samples submitted for CMV AVDR testing from 2011 to 2019.

Population immunity to measles in Canada using Canadian Health Measures survey data - A Canadian Immunization Research Network (CIRN) study.

We aimed to determine population immunity to measles in Canada, and to assess the risk of future outbreaks. We tested 11,176 sera from Cycles 2 (2009-2011) and 3 (2011-2013) cohorts from the biobank of Statistics Canada's Canadian Health Measures Survey (CHMS) using the BioPlex 2220 MMRV IgG assay. We then tested all BioPlex negative and equivocal samples using a more sensitive Plaque Reduction Neutralization Test (PRNT).

Optimisation of methodology for whole genome sequencing of Measles Virus directly from patient specimens.

In an era of decreasing genetic diversity of Measles Virus (MeV), effective surveillance requires a higher-resolution genotyping method or whole genome sequencing (WGS) to document elimination. Through optimization of MeV WGS protocol, we developed a MeV-specific probe enrichment method that allows next generation sequencing from clinical specimens. With the probe enrichment method, 70% of specimens can be sequenced at a read depth of greater than 10 reads with minimal off-target sequences.

Next-generation sequencing for cytomegalovirus antiviral resistance genotyping in a clinical virology laboratory.

Introduction: The identification of CMV antiviral drug resistance (AVDR) is a critical diagnostic test for immunocompromised patients with CMV infection and a failure of virologic response on optimal antiviral treatment. We developed a next-generation sequencing (NGS) assay for CMV AVDR testing and compared the AVDR mutations identified by NGS to Sanger sequencing.

Methods: Retrospective review of CMV AVDR testing requests for UL97 and UL54 at our laboratory from 2014 to 2019 was conducted.

An enrichment method for capturing mumps virus whole genome sequences directly from clinical specimens.

Recently there has been a significant increase in the number of mumps outbreaks occurring in highly vaccinated populations. These outbreaks are often due to a mumps genotype G virus, where sequencing of the SH gene does not reveal enough genetic diversity to sufficient to resolve outbreaks. This has elevated the need to be able to sequence complete mumps viruses from clinical samples without laborious methods.

Evaluation of a commercially-available surrogate virus neutralization test for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2).

There remains an urgent need for assays to quantify humoral protective immunity to SARS-CoV-2 to understand the immune responses of COVID-19 patients, evaluate efficacy of vaccine candidates in clinical trials, and conduct large-scale epidemiological studies. The plaque-reduction neutralization test (PRNT) is the reference-standard for quantifying antibodies capable of neutralizing SARS-CoV-2. However, the PRNT is logistically demanding, time-consuming, and requires containment level-3 facilities to safely work with live virus.

Measles Antibody Levels in Young Infants.

Background: Infants are often assumed to be immune to measles through maternal antibodies transferred during pregnancy and, in many countries, receive their first measles-containing vaccine at 12 to 15 months. Immunity may wane before this time in measles-eliminated settings, placing infants at risk for measles and complications. We investigated humoral immunity to measles in infants <12 months of age in Ontario, Canada.

Assessment of population immunity to measles in Ontario, Canada: a Canadian Immunization Research Network (CIRN) study.

Canada eliminated measles in 1998. We conducted a sero-epidemiology study to estimate population immunity to measles in the province of Ontario, Canada and to identify groups at higher risk of outbreaks. We used a previously developed modified enzyme immunoassay to test 1,199 residual sera from patients aged 1-39 years.

Calibration and Evaluation of Quantitative Antibody Titers for Varicella-Zoster Virus by Use of the BioPlex 2200.

Most commercially available enzyme immunoassay-based methods have limited sensitivity to detect antibody responses to varicella-zoster virus (VZV) in vaccinated individuals, who produce lower antibody levels than those with natural infection. However, more sensitive methods are either not commercially available or less amenable to high-throughput testing. The BioPlex 2200 measles, mumps, rubella, and varicella (MMRV) IgG assay (Bio-Rad Laboratories, Hercules, CA) is an automated high-throughput platform based on the microsphere Luminex technology that measures antibodies against measles, mumps, rubella, and varicella viruses simultaneously.

Calibration and Evaluation of Quantitative Antibody Titers for Measles Virus by Using the BioPlex 2200.

The BioPlex 2200 (Bio-Rad Laboratories, Hercules, CA) is a rapid, automated platform, which can screen large numbers of specimens for antibodies to measles, mumps, rubella, and varicella. Although approved for producing qualitative results, in this study we validated the test (off-label) to allow reporting of quantitative results. To do this, we used the third anti-measles World Health Organization standard to generate a calibration curve that allowed relative fluorescence intensity to be translated into quantitative antibody titer (antibody units [AU]/ml).

ODDD-linked Cx43 mutants reduce endogenous Cx43 expression and function in osteoblasts and inhibit late stage differentiation.

Introduction: Bone development and modeling requires precise gap junctional intercellular communication (GJIC). Oculodentodigital dysplasia (ODDD) is an autosomal dominant human disease caused by mutations in the gene (GJA1) encoding the gap junction protein, connexin43 (Cx43). The disease is characterized by craniofacial bone deformities and limb abnormalities.

Connexins and gap junctions in mammary gland development and breast cancer progression.

The development and function of the mammary gland require precise control of gap junctional intercellular communication (GJIC). Here, we review the expression and function of gap junction proteins, connexins, in the normal mouse and human mammary gland. We then discuss the possible tumor-suppressive role of Cx26 and Cx43 in primary breast tumors and through the various stages of breast cancer metastasis and consider whether connexins or GJIC may actually promote tumorigenesis at some stages.

Connexins act as tumor suppressors in three-dimensional mammary cell organoids by regulating differentiation and angiogenesis.

Connexins are tumor suppressors, and human breast connexin 26 (Cx26) and connexin 43 (Cx43) gap junctions are often down-regulated in breast cancer. We previously showed that Cx26 and Cx43 overexpressed in MDA-MB-231 breast cancer cells inhibited tumor growth in vivo but not in two-dimensional cultures. In the current study, we show that overexpression of Cx26 or Cx43 has tumor-suppressive properties in a three-dimensional environment such that they reduced anchorage-independent cell growth and induced partial redifferentiation of three-dimensional organoids of MDA-MB-231 cells.

Functional characterization of oculodentodigital dysplasia-associated Cx43 mutants.

Oculodentodigital dysplasia (ODDD) is associated with at least 28 connexin43 (Cx43) mutations. We characterized four of these mutants; Q49K, L90V, R202H, and V216L. Populations of these GFP-tagged mutants were transported to the cell surface in Cx43-negative HeLa cells and Cx43-positive NRK cells.

Down-regulation of Cx43 by retroviral delivery of small interfering RNA promotes an aggressive breast cancer cell phenotype.

Connexins are gap junction proteins that assemble into channels that mediate direct intercellular communication. Connexins are well-documented tumor suppressors and are thought to regulate both cell growth and differentiation. As previously reported, most human breast tumors and cell lines down-regulate gap junctions or have defective gap junctional intercellular communication.

Oculodentodigital dysplasia-causing connexin43 mutants are non-functional and exhibit dominant effects on wild-type connexin43.

Oculodentodigital dysplasia, a rare condition displaying congenital craniofacial deformities and limb abnormalities, has been associated with over 20 known human connexin43 (Cx43) mutations. The localization of two of these mutants, G21R and G138R, was examined in Cx43-positive normal rat kidney cells (NRK) and Cx43-negative gap junctional intercellular communication-deficient HeLa cells. Green fluorescent protein-tagged and untagged Cx43 G21R and G138R mutants were transported to the plasma membrane and formed punctate structures reminiscent of gap junction plaques in both NRK and HeLa cells.

Biophysical characterization of zebrafish connexin35 hemichannels.

A subset of connexins can form unopposed hemichannels in expression systems, providing an opportunity for comparison of hemichannel gating properties with those of intact gap junction channels. Zebrafish connexin35 (Cx35) is a member of the Cx35/Cx36 subgroup of connexins highly expressed in the retina and brain. In the present study, we have shown that Cx35 expression in Xenopus oocytes and N2A cells produced large outward whole cell currents on cell depolarization.

Zebrafish Cx35: cloning and characterization of a gap junction gene highly expressed in the retina.

The vertebrate connexin gene family encodes protein subunits of gap junction channels, which provide a route for direct intercellular communication. Consequently, gap junctions play a vital role in many developmental and homeostatic processes. Aberrant functioning of gap junctions is implicated in many human diseases.