This current installment of the case study column concerns the role of the medical librarian in basic biological research. In the modern life sciences, the boundaries between the health professions and general biology are becoming increasingly blurred, as both disciplines rely to a greater extent on interdisciplinary, integrative, and comparative approaches for the resolution of major questions (Figure 1). Correspondingly, the university medical or health center library is rapidly becoming a primary resource for both basic and applied scientists from across virtually all fields of modern biology (e.g., from molecular and cellular biology to physiology to ecology and evolution). In response, the importance of the medical librarian as an information specialist continues to grow at these institutions. This case study documents this expanding role of the medical librarian by focusing on a basic research question that originated from a recent publication on viral evolution. The authors and editors invite your commentary on this case online at http://www.jmlacasestudies.blogspot.com. Figure 1 Evolutionary biologist (Miyamoto) commentary The Case JC virus (JCV) is a common virus in humans, its natural host* [1]. (Terms asterisked upon first appearance are defined in Table 1.) This virus was first isolated in 1971 from an immunocompromised* patient with the initials “J. C.” [2]. It is estimated that by age 20, nearly 90% of humans worldwide are infected with this virus based on the presence of JCV-specific antibodies [3]. Normally, JCV is not associated with any health problems, except in immunocompromised patients. In such patients, JCV infection can lead to progressive multifocal leukoencephalopathy (PML*), a fatal neurological disease [4]. Table 1 Key concepts for this case study A virus depends on its host for its survival and reproduction [5,6]. Conversely, to the host, a virus represents a foreign element, which may lower its fitness*. Thus, viral evolution should mirror host evolution (and vice versa), because the survival and reproduction of the two are intertwined. In more formal terms, the expectation is for the virus and host to coevolve over time. Working from this premise of coevolution*, Kitchen et al. [7] recently used DNA sequence data to compare the evolution and history of JCV to those of its human host. In contrast to almost all previous studies of the virus, these authors concluded that JCV was rapidly evolving on a timescale of decades to centuries, rather than tens of thousands of years [8–10]. Thus, their study indicated that the contemporary regional patterns of JCV diversity were due to a recent, rather than ancient, coevolutionary history with humans. The second author of Kitchen et al. [7] is also the second author of this current case study (Miyamoto). One reviewer of the original manuscript [7] questioned whether JCV integrates into the chromosomes of its human host during its normal life cycle. Specifically, this reviewer wrote: “from what I have read, some fraction of the time virus integrates and then replicates like a cellular gene …. On this basis, is it possible that there are two mutation rates, one reflecting cellular replication and one reflecting viral replication? Presumably, the former rate would be slower.” In some types of viruses, viral DNA is integrated into the host's chromosome, and as such, the viral DNA becomes physically connected to the host's DNA. As recognized by this reviewer, the question of viral integration* is an important one, because an integrated JCV would be expected to evolve at the same (slow) rate as that for its host chromosome DNA, to which it would be physically linked. Thus, evidence of viral integration would oppose Kitchen et al.'s conclusion of a fast JCV rate [7]. In response to this reviewer, Kitchen et al. conducted a literature search to assess whether JCV integration is part of its normal life cycle. Based on this search, these authors reported in their final publication that “JCV replicates in the host cell nucleus, but does not integrate into the latter's chromosomes” [11]. Importantly, Khalili et al. [11] did not provide a definitive “yes or no” answer to the question of JCV integration. Nor did their article review the primary experimental evidence or citations in favor of or against this possibility. Instead, their article presented a basic introduction to the life cycle of JCV, which made no reference to viral integration. In the absence of a statement by them to the contrary, Kitchen et al. [7] cited their paper as at least implicit support for the absence of JCV integration during its normal life cycle. However, as scientists, the three authors in general and one biologist in particular (Miyamoto) remain interested in whether hard experimental evidence exists in the primary literature for an explicit resolution of this problem. The biologist approaches you as an information specialist and asks for your aid in thoroughly searching this literature.