HHV-6 IgG4 isotype response following measles infection

Area of Science:

• Immunology
• Virology
• Infectious Diseases

Background:

• Human herpesvirus 6 (HHV-6) is a common virus establishing lifelong latency in most individuals.
• HHV-6 reactivation or altered immune responses can occur during other viral infections.
• Understanding HHV-6 specific antibody responses is crucial for diagnosing and managing coinfections.

Purpose of the Study:

• To investigate the specific IgG subclass (IgG1, IgG2, IgG3, IgG4) responses to HHV-6.
• To compare these responses in individuals with natural measles virus infection, measles vaccination, rubella virus infection, and healthy controls.
• To determine if acute viral coinfections influence the HHV-6 specific immune profile.

Main Methods:

• Serum samples were collected from HHV-6 seropositive individuals with various infection/vaccination statuses.
• Indirect immunofluorescence assays were used to detect HHV-6 specific IgG1, IgG2, IgG3, and IgG4 antibodies.
• Statistical analysis (chi-squared test) was employed to compare antibody responses between groups.

Main Results:

• A significant majority (69%) of individuals with natural measles virus infection exhibited an HHV-6 IgG1 and IgG4 response (P < 0.001).
• Individuals who received the measles vaccine, had rubella virus infection, or were healthy controls showed an HHV-6 IgG1 response.
• No significant differences were noted in IgG2 or IgG3 responses across the groups.

Conclusions:

• Natural measles virus infection strongly induces a specific HHV-6 IgG1 and IgG4 antibody response.
• This distinct response pattern suggests a shift from a T-helper 1 (Th1) to a T-helper 2 (Th2) immune response during measles infection.
• The findings highlight the impact of concurrent viral infections on the host's humoral immunity to latent viruses like HHV-6.