Cytomegalovirus ("CMV") is among the most common infections following solid-organ transplantation and hematopoietic stem cell transplant procedures, causing disease, transplant complications, and adverse outcomes.By age 40, between 50 and 80 percent of U.S. adults will have had a CMV infection. Following the primary infection, the CMV virus typically remains dormant, but it can reactivate and cause illness in immunocompromised persons.

Given their immunocompromised state, recipients of organ and stem cell transplant are at particular risk of suffering CMV-related complications. Despite improved CMV awareness and monitoring by transplant physicians, and management with antiviral drugs, the incidence of CMV complications remains high, with estimates ranging from 20 to 70 percent in the first year following transplantation.CMV complications commonly include pneumonia (shortness of breath, cough), GI disease (abdominal pain, bleeding, diarrhea), CNS disease (altered mental status, cognitive dysfunction), and retinitis (blurring or loss of central vision, scotomata). The type of CMV complications vary by patient population – for instance, CMV pneumonia is more common following stem cell transplant procedures, and CMV retinitis is more common in among persons living with HIV/AIDS.

Complications also relate to the indirect effects of CMV on the patient’s immune system, with a myriad of studies showing that CMV disease increases the incidence of graft rejection, graft injury, and graft failure. Secondary fungal and bacterial infections are also common. CMV infection and disease is associated with longer hospital stays and increased care costs.

Transplant Society Recommendations

In December 2008, a panel of CMV and solid-organ transplant experts met with the Infectious Diseases Section of The Transplantation Society to develop consensus guidelines for managing CMV. First published in 2010, and later revised in 2012, topics covered include CMV diagnosis, risk assessment, prevention, and treatment.

The Transplantation Society recommends that CMV screening be performed before transplantation to guide the treatment approach. The Transplantation Society also suggests that physicians consider administering antiviral medications to patients most at-risk.

To reduce the impact of CMV disease, antivirals are usually begun following the transplant procedure and continued for three to six months or longer. Several antivirals have been evaluated including acyclovir, valacyclovir, ganciclovir, and valganciclovir. Valganciclovir is increasingly being used as the preferred medication for treatment.

Despite significant advances in the prevention and management of CMV, The Transplantation Society has suggested that an effective CMV vaccine, like the one VBI hopes to produce, could satisfy the large need for preventing CMV infection or reactivation post-transplantation.

VBI is developing a prophylactic vaccine to prevent CMV infection – based on preclinical data, VBI has initiated work for GMP manufacturing of its lead candidate for use in formal preclinical and Phase I trials.