CDC waiting for H7N9 sample to speed test kits

Apr 8, 2013 (CIDRAP News) – A human isolate of the novel H7N9 influenza virus from China—needed for the development of diagnostic test kits and related efforts—is expected to arrive at the Centers for Disease Control and Prevention (CDC) within 2 days, a CDC official said today.

Michael Shaw, PhD, associate laboratory director in the CDC's Influenza Division, said he expects to receive the isolate late tomorrow or the next day. China has reported 24 illnesses linked to the virus so far, 7 of them fatal and most of the rest severe.

CDC officials said on Apr 5 that they had already developed a diagnostic test for their own use and were working on a diagnostic test kit for use by the states and other countries.

Today Shaw said the CDC is already far along in developing a real-time polymerase chain reaction (PCR) test kit for the virus, using the DNA sequence information provided earlier by the Chinese government. The sequence data made it possible to synthesize primers and probes.

"As soon as we get the actual virus this week, we'll test against that," he said. "We should be able to ship [diagnostic test kits] possibly next week to the noncommercial state labs and the WHO [World Health Organization] system."

State public health labs will have priority for the test kits, but the CDC also will send them to WHO collaborating centers and to national influenza labs in more than 100 countries, Shaw said.

The H7N9 isolate will also be used to see if commercially available flu tests detect the virus, Shaw said. "We're fairly certain that if it [a test] can pick up influenza A, it'll be able to pick this up," though it wouldn't distinguish the subtype, he said. The evaluation will include commercial rapid tests.

Using the isolate, the agency also will look at whether the virus is sensitive to antiviral drugs, Shaw reported. The WHO has said that preliminary test results from its collaborating center in China suggest that the virus is susceptible to oseltamivir (Tamiflu) and zanamivir (Relenza), but that still awaits confirmation.

Human isolates will also be used in developing a candidate vaccine, Shaw said.

He reported last week that the CDC was already working on a vaccine, using the sequence data available, and that actual isolates would be used for the same purpose when available.

Having an isolate "will give us a chance to have an actual standard to compare the antibody response to the vaccine strains," Shaw said today.

China to develop vaccine
In other developments, a Chinese health official said China is starting to develop a vaccine for H7N9, but it will be produced in quantity only if the virus starts to spread from person to person, according to Xinhua, the national news service.

Liang Wannian, director of H7N9 response for the National Health and Family Planning Commission (NHFPC), said it may take 6 to 8 months to bring the vaccine to market, if the government decides to proceed.

Another NHFPC official, Deng Haihua, said the agency is also considering using traditional Chinese medicine in responding to the outbreak, Xinhua reported.

Also, another news report said the China Food and Drug Administration has decided to "fast-track" approval for the intravenous antiviral drug peramivir, which, like oseltamivir and zanamivir, is a neuraminidase inhibitor. The report came yesterday from the South China Morning Post, a Hong Kong newspaper.

Peramivir is used in Japan but is not licensed in the United States. The story gave no details on how soon China might approve the drug.

USDA reaffirms import ban
In another development, the H7N9 outbreak prompted the US Department of Agriculture (USDA) on Apr 5 to issue an import alert reaffirming its existing ban on poultry imports from countries that have highly pathogenic avian influenza in commercial poultry, a USDA spokesman told CIDRAP News today.

China was already subject to the ban because of H5N1 avian flu, which has long been present there.

The USDA official noted that all commercial poultry flocks in the United States are tested for avian flu through industry, state, and federal efforts

See also:

Apr 5 CIDRAP News story "CDC working on vaccine, tests for novel H7N9 virus"

Apr 8 Xinhua story

Apr 7 South China Morning Post story

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