Going to Bat

Going to Bat
NATURAL RESERVOIR FOR EMERGING VIRUSES MAY BE BATS BY CHARLES Q. CHOI

Bats are creatures of the night that are commonly held in fear. At first glance, those fears might seem to have some medical justification. Long known as vectors for rabies, bats may be the origin of some of the most deadly emerging viruses, including SARS, Ebola, Nipah, Hendra and Marburg. Instead of demonizing bats, however, research shows the real culprit behind these outbreaks could be human error.

The Nipah and Hendra viruses were the first emerging diseases linked to bats. Hendra claimed two of its three victims in its first and so far only known appearance in Australia. Meanwhile Nipah has in repeated Southeast Asian outbreaks killed nearly 200 people, and blood tests of wildlife have suggested that the viruses came from the largest bats, flying foxes.

The connection to SARS, or severe acute respiratory syndrome, was less direct. During the outbreak that began in China in 2002, investigators found that civets and two unrelated species harbored the SARS coronavirus, prompting mass culling of the mongooselike civets by the Chinese government.

Subsequent research, however, found no widespread SARS infection among wild or farmed civets, indicating that the disease arose in another species and might remain in wait there.

From research with Nipah and Hendra, virologist Linfa Wang of the Australian Animal Health Laboratory new bats could get chronic infections from the viruses while not getting sick, making them ideal carriers for disease. Bats, civets and a menagerie of other animals were often found caged near one another in live-animal markets in Asia.

So Wang hypothesized that bats might harbor SARS as well. Wang and his colleagues analyzed blood, throat and fecal swabs from 408 wild bats from China. Genetic analysis revealed five bats, which represented three of nine species of horseshoe bats tested, possessed viruses closely related to SARS. They reported last September that the genetic variation within those coronaviruses was far greater than that seen in human or civet SARS.

Therefore, bats, probably having lived longer with the diseases, may be the origin of the coronaviruses seen in other species. Then, in December, researchers connected fruit bats to Ebola, whose origin in the wild had remained unknown since its first recorded appearance 30 years ago.

During the Ebola outbreaks in humans, gorillas and chimpanzees between 2001 and 2003 in Gabon and the Republic of the Congo, a team led by virologist Eric M. Leroy of the International Center of Medical Research in Franceville, Gabon, tested some 1,000 animals. Of 679 bats studied, 16 had antibodies against Ebola, and 13 others possessed Ebola gene sequences in their liver and spleen. The sequences demonstrated

genetic diversity, “indicating that Ebola probably has spent a long time within bats, suggesting that bats might be the origin,” Leroy says. Virologist W. Ian Lipkin of Columbia University notes that scientists suspect that the Marburg virus, a relative of Ebola, also originated in bats.

Leroy vigorously argues that bats should not be culled. Wang agrees, observing that bats play critical ecological roles, such as eating insects and other pests. Besides, Wang points out, culling is simply not practical when it comes to bats, which can just fly away. Satellite collars on fruit bats carrying Nipah showed they could fly between Thailand, Sumatra and Malaysia, and the horseshoe bats linked with SARS range across Asia, Europe and Australia.

Preventing future emergences may instead focus on human behavior. Just as SARS is potentially linked to animal markets, so was Nipah linked to pigpens encroaching on bat habitats. And people living in Ebola-endemic areas eat the bats harboring the virus. Knowledge that bats can carry dangerous viruses could work to prevent epidemics, notes Peter Daszak, executive director of the New York City–based Consortium for Conservation Medicine, which studies the connection between emerging diseases and human interactions with the environment. Keeping bats from the wildlife trade might have dramatically cut the risk of SARS emerging, perhaps saving $50 billion worldwide in loss to travel, trade and health care costs “and hundreds of lives,” Daszak says.

Testing Lethality

Plates of sugar could indicate the deadliness of a flu strain. The influenza virus infects the body using hemagglutinin, a viral protein that latches onto sugars containing sialic acids on human cell surfaces.

Scripps research Institute investigators and their colleagues developed arrays containing 200 different carbohydrates and sugary proteins, representing the major types of molecules to which hemagglutinin might attach. They tested eight different flu strains, including the deadly 1918 infl uenza, and discovered that alterations at as few as two positions on the hemagglutinin protein can transform a bird strain into one that can infect humans.

The scientists, who report the work in the February 3 Journal of Molecular Biology, say that the arrays could explain why the 1918 flu, which strongly resembles avian viruses, was so devastating. They could also lead to monitors that quickly determine how close another bird strain is to mutating into a pandemic form. —Charles Q. Choi

Flexi Divre III Jawa Barat dan Banten Mulai Beroperasi di Frekuensi 800 MHz

PT Telekomunikasi Indonesia Tbk (Telkom) Divisi Regional III Jawa Barat dan Banten mulai mengoperasikan Flexi pada frekuensi 800 MHz mulai 24 Oktober 2007. Sementara untuk Divisi Regional II Jabodetabek-Sekapur pelayanan Flexi di frekuensi 800 MHz rencananya akan beroperasi pada bulan November 2007.

Vice President Public & Marketing Communication Telkom, Eddy Kurnia mengatakan terhitung tanggal 24 Oktober 2007 pukul 20.30 seluruh BTS (Base Tranceiver Station) Flexi di Jawa Barat dan Banten sudah on pada frekuensi 800 MHz. Namun demikian, frekuensi Flexi di 1900 MHz masih digunakan hingga 31 Desember 2007.

Eddy Kurnia menegaskan dengan migrasi frekuensi dari 1900 MHz ke 800 Mhz ini akan memperlebar daya jangkau sinyal Flexi, sehingga akan memperluas layanan Telkom Flexi. Perubahan frekuensi ini merupakan tindak lanjut pembenahan frekuensi yang dilakukan pemerintah. ''Pemerintah telah mengalokasikan frekuensi 1900 MHz untuk telepon selular generasi ketiga sehingga Flexi diminta pindah ke frekuensi 800 MHz,'' jelasnya dalam siaran pers yang diterima Republika, Selasa (30/10).

Berkaitan dengan kompensasi bagi pemilik terminal Flexi single band 1900 MHz, Eddy Kurnia menjelaskan, khusus untuk pelanggan di Jawa Barat dan Banten pelaksanaan pemberian kompensasi akan dimulai pada tanggal 1 November 2007, sedangkan untuk daerah Jabodetabek waktunya segera ditentukan.

Pemberian kompensasi di Jawa Barat akan dimulai di Subang, Sumedang, Kuningan, Garut, Indramayu dan Majalengka, setelah itu daerah-daerah lainnya segera menyusul. Telkom, kata Eddy Kurnia, telah memverifikasi para pelanggan yang memilih opsi pengantian handset. Telkom juga memberikan pilihan lain, seperti voucher dan extra balance atau gabungan kupon pengganti pulsa dan voucher. (fir/rep)

The Advantage of Keeping Quiet

The Hawaiian Islands have long been known as a natural laboratory for studying evolution. Zuk et al. have assessed the effect of the selective pressure of parasitoid flies on Teleogryllus field crickets introduced to the island of Kauai. Female flies locate male crickets when they call to female crickets, and lay their eggs on the cricket; the larvae burrow into the host and consume it from within, eventually killing it. Over just 20 generations, the singing males dwindled in abundance owing to the selective pressure from the parasitoid, and a new, silent type of male—known as flatwings—became prevalent. Given that the song functions as a signal to potential mates, how do the flatwing males attract female partners?

Field experiments suggest that the silent males congregate around the few remaining singers,
increasing the chance of intercepting inquisitive females (who have possibly relaxed their
requirement that the male keep singing up to the moment of mating). Thus, natural selection has not only had a rapid population genetic effect; there has been a behavioral response as well. It remains to be seen, however, if the singing males are now too rare to support the local parasitoid population, or if the singing males will disappear entirely (and, if so, whether the crickets will find a new solution to the problem of finding mates). — AMS