Genetic identification of cytomegaloviruses in a rural population of Côte d'Ivoire

On the Demographic and Selective Forces Shaping Patterns of Human Cytomegalovirus Variation within Hosts

Human cytomegalovirus (HCMV) is a member of the β -herpesvirus subfamily within Herpesviridae that is nearly ubiquitous in human populations, and infection generally results only in mild symptoms. However, symptoms can be severe in immunonaive individuals, and transplacental congenital infection of HCMV can result in serious neurological sequelae. Recent work has revealed much about the demographic and selective forces shaping the evolution of congenitally transmitted HCMV both on the level of hosts and within host compartments, providing insight into the dynamics of congenital infection, reinfection, and evolution of HCMV with important implications for the development of effective treatments and vaccines.

Seroprevalence of Cytomegalovirus Infection Among a Rural Population of Côte d'Ivoire

Human cytomegalovirus (HCMV) is a betaherpesvirus that can be pathogenic to humans. In particular, immunocompromised patients can develop life-threatening symptoms. In the present study, HCMV seroprevalence was investigated in a rural population of Western Côte d'Ivoire. Plasma samples collected from 166 apparently healthy subjects living in 8 villages surrounding the Taï Forest National Park were tested for anti-HCMV immunoglobulin G and M antibody with two commercial enzyme-linked immunosorbent assays. Prevalence of anti-HCMV IgG and IgM antibody was 100% and 5.4%, respectively. Anti-HCMV IgM positive was 10.2% (5/49) of the children and adolescents and 3.4% (4/117) of the adults. This observed decrease of IgM seropositivity and the seroprevalence difference between males and females (3.8% vs. 6.1%) was not statistically significant. In plasma of one IgM-positive participant, a low CMV load was detected indicating low-level replication. A second IgM-positive participant showed signs of local CMV replication. The other seven IgM-positive plasma samples likely reacted nonspecifically or due to polyclonal stimulation. Taken together, the results indicate that HCMV infection is hyperendemic in Côte d'Ivoire.

Cytomegaloviruses in a Community of Wild Nonhuman Primates in Taï National Park, Côte D'Ivoire

Cytomegaloviruses (CMVs) are known to infect many mammals, including a number of nonhuman primates (NHPs). However, most data available arose from studies led on captive individuals and little is known about CMV diversity in wild NHPs. Here, we analyzed a community of wild nonhuman primates (seven species) in Taï National Park (TNP), Côte d’Ivoire, with two PCR systems targeting betaherpesviruses. CMV DNA was detected in 17/87 primates (4/7 species). Six novel CMVs were identified in sooty mangabeys, Campbell’s monkeys and Diana monkeys, respectively. In 3/17 positive individuals (from three NHP species), different CMVs were co-detected. A major part of the glycoprotein B coding sequences of the novel viruses was amplified and sequenced, and phylogenetic analyses were performed that included three previously discovered CMVs of western red colobus from TNP and published CMVs from other NHP species and geographic locations. We find that, despite this locally intensified sampling, NHP CMVs from TNP are completely host-specific, pinpointing the absence or rarity of cross-species transmission. We also show that on longer timescales the evolution of CMVs is characterized by frequent co-divergence with their hosts, although other processes, including lineage duplication and host switching, also have to be invoked to fully explain their evolutionary relationships.

Killer-cell immunoglobulin-like receptors and cytomegalovirus reactivation during late pregnancy

Human cytomegalovirus (CMV) represents an important public health concern as it is associated with severe morbidity and mortality in transplant recipients, HIV-infected individuals and pregnant women given the risk of congenital infection. Congenital CMV is a leading cause of neurological sequelae, developmental delay and birth defects worldwide. Cytomegalovirus can be transmitted to the foetus following maternal infection or reactivation. NK cells expressing killer-cell immunoglobulin-like receptors (KIR) are part of the innate immune system and the first line of defence against viral incursions. Previous reports have shown that KIR genes are associated with CMV infections in the post-transplant setting. In this study, we set out to determine whether a protective effect of KIR genes over CMV infection is seen in Mexican pregnant women. Cytomegalovirus infection was assessed through nucleic acid testing in 200 pregnant women and 600 healthy blood donors comprising the Mexican mestizo reference population. Killer-cell immunoglobulin-like receptors and HLA-C genotypes were obtained from 200 pregnant women and 300 reference samples using a comprehensive PCR-SSP approach. We observed statistically lower carrier frequencies of cB03|tA01 gene-content haplotype, of cB03 haplotype motif, of the KIR2DL5 + 2DS3/2DS5 gene pair and of KIR2DL5 amongst CMV-positive pregnant women in comparison with those CMV negative. None of these were associated with CMV status in the reference population. Logistic regression analysis revealed that the most important factor determining CMV status during third-trimester pregnancies was the KIR2DL5 + 2DS3/2DS5 gene pair (OR 0.376 (95%CI 0.174, 0.811, P = 0.013). Our results indicate that CMV-protective KIR gene associations described in Caucasoid populations are also present in the genetically distinct Mexican mestizo population. Our results suggest that certain KIR gene combinations provide protection against CMV infections occurring during late-term pregnancies, a finding of utmost epidemiological importance given its implication with congenital CMV infections.

Cytomegalovirus-based vaccine expressing Ebola virus glycoprotein protects nonhuman primates from Ebola virus infection

Ebolaviruses pose significant public health problems due to their high lethality, unpredictable emergence, and localization to the poorest areas of the world. In addition to implementation of standard public health control procedures, a number of experimental human vaccines are being explored as a further means for outbreak control. Recombinant cytomegalovirus (CMV)-based vectors are a novel vaccine platform that have been shown to induce substantial levels of durable, but primarily T-cell-biased responses against the encoded heterologous target antigen. Herein, we demonstrate the ability of rhesus CMV (RhCMV) expressing Ebola virus (EBOV) glycoprotein (GP) to provide protective immunity to rhesus macaques against lethal EBOV challenge. Surprisingly, vaccination was associated with high levels of GP-specific antibodies, but with no detectable GP-directed cellular immunity.